Endmyopia Wiki - User contributions [en]

Severe myopia

2022-05-31T15:26:49Z

Gene Onco: Fix typo

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge. You can determine how thick the lenses will get if you know all the parameters using [https://opticampus.opti.vision/tools/thickness.php this handy thickness calculator].

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small-diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index lenses are subject to much stronger reflections at the lens/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' lenses.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since high-index glass or plastic has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===For a large field of view, choose plastic lenses and thick rims===
The density of plastic lenses is a few times lower than that of glass lenses. Hence, high-strength plastic lenses with a regular diameter and thus good field of view can still be reasonably light. But the refractive index of plastic lenses goes up to only 1.6 or 1.7 so that plastic lenses will have thicker edges than can be achieved with glass. These thick edges can be masked by choosing a frame with thick rims.<ref name="Jan">https://community.endmyopia.org/t/high-myope-says-hi/18100/42</ref>
===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes when looking straight ahead. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. At the same time, the angular coverage of the lens increases so that you have a larger field of view. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent and the field of view is not clipped. This is the case when you wear contact lenses. For glasses you can get these benefits to some degree by choosing a frame with really small diameter lenses and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

===Simplifying accounting for vertex distance===
By picking the same frame when buying new glasses, the vertex distance will not change. This makes it easier to compare the strengths of successive pairs of glasses. When the frame comes in different colors, you can cycle through the colors to prevent confusing the old glasses for the new ones.<ref name="Jan"/>

Severe myopia

2022-05-31T15:22:57Z

Gene Onco: Improve phrasing and pluralize

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge. You can determine how thick the lenses will get if you know all the parameters using [https://opticampus.opti.vision/tools/thickness.php this handy thickness calculator].

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small-diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index lenses are subject to much stronger reflections at the lens/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' lenses.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since high-index glass or plastic has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===For a large field of view, choose plastic lenses and thick rims===
The density of plastic lenses is a few times lower than that of glass lenses. Hence, high-strength plastic lenses with a regular diameter and thus good field of view can still be reasonably light. But the refractive index of plastic lenses goes up to only 1.6 or 1.7 so that plastic lenses will have thicker edges than can be achieved with glass. These thick edges can be masked by choosing a frame with thick rims.<ref name="Jan">https://community.endmyopia.org/t/high-myope-says-hi/18100/42</ref>
===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes when looking straight ahead. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. At the same time, the angular coverage of the lens increases so that your have a larger field of view. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent and the field of view is not clipped. This is the case when you wear contact lenses. For glasses you can get these benefits to some degree by choosing a frame with really small diameter lenses and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

===Simplifying accounting for vertex distance===
By picking the same frame when buying new glasses, the vertex distance will not change. This makes it easier to compare the strengths of successive pairs of glasses. When the frame comes in different colors, you can cycle through the colors to prevent confusing the old glasses for the new ones.<ref name="Jan"/>

Severe myopia

2022-05-31T15:11:31Z

Gene Onco: Add Jan's strategies

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge. You can determine how thick the lenses will get if you know all the parameters using [https://opticampus.opti.vision/tools/thickness.php this handy thickness calculator].

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small-diameter lenses clip your field of view.
===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index lenses are subject to much stronger reflections at the lens/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' lenses.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since high-index glass or plastic has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.
===For a large field of view, choose plastic lenses and thick rims===
The density of plastic lenses is a few times lower than that of glass lenses. Hence, high-strength plastic lenses with a regular diameter and thus good field of view can still be reasonably light. But the refractive index of plastic lenses goes up to only 1.6 or 1.7 so that plastic lenses will have thicker edges than can be achieved with glass. These thick edges can be masked by choosing a frame with thick rims.<ref name="Jan">https://community.endmyopia.org/t/high-myope-says-hi/18100/42</ref>
===Pick frames with a well-matching pupillary distance===

Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes when looking straight ahead. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.
===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. At the same time, the angular coverage of the lens increases so that your have a larger field of view. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent and the field of view is not clipped. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

===Simplifying accounting for vertex distance===

By picking the same frame when buying new glasses, the vertex distance will not change. This makes it easier to compare the strengths of successive pairs of glasses. When the frame comes in different colors, you can cycle through the colors to prevent confusing the old glasses for the new ones.<ref name="Jan"/>

Pupillary Distance

2022-05-31T08:53:31Z

Gene Onco: Make heading reflect content

Pupillary Distance (PD) is the distance between your pupil centers. This measurement is important when ordering glasses to make sure you are looking through the optical centers of your lenses. If you have glasses made by an [[optician]] they may take additional measurements, but those require the frame to be on your face, and standard values are used by online glasses suppliers for those measurements. This is fine for most people, but may be a source of discomfort for some.

Preferably do not use a single number for PD, use the separate distances for each eye measured to centre of the bridge of nose: many people are not perfectly symmetric"<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/4?</ref>

==Near PD==
Because your eyes [[converge]] when looking at nearby objects, your PD is going to be smaller when doing [[near work]] than for [[distance vision]]. If you are buying [[differentials]] or [[reading glasses]] your near PD should therefore be used.

==Pupillary Distance and Frames==
It also helps if you figure out what size frames fit your head. One trick I read online is that the PD of the frames themselves in mm units is the sum of the first two numbers on the frame. So if you have frames that are 53-15-140, the PD of the frame is 53 + 15 = 68mm. In general, you’ll do better with frames that are close to your actual PD: your eyes will be centered in the frames, and the lenses will be centered in the frame too.<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/3</ref>

==Measuring your PD==

See Jake's blog post [https://endmyopia.org/how-to-measure-pd-pupillary-distance/ Headaches & Fatigue: Measure Your Pupillary Distance (PD)].
==Citations==
[[Category:Articles]]

Pupillary Distance

2022-05-31T08:47:52Z

Gene Onco: Clarify phrasing

Pupillary Distance (PD) is the distance between your pupil centers. This measurement is important when ordering glasses to make sure you are looking through the optical centers of your lenses. If you have glasses made by an [[optician]] they may take additional measurements, but those require the frame to be on your face, and standard values are used by online glasses suppliers for those measurements. This is fine for most people, but may be a source of discomfort for some.

Preferably do not use a single number for PD, use the separate distances for each eye measured to centre of the bridge of nose: many people are not perfectly symmetric"<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/4?</ref>

==Near PD==
Because your eyes [[converge]] when looking at nearby objects, your PD is going to be smaller when doing [[near work]] than for [[distance vision]]. If you are buying [[differentials]] or [[reading glasses]] your near PD should therefore be used.

==Pupillary Distance and Frames==
It also helps if you figure out what size frames fit your head. One trick I read online is that the PD of the frames themselves in mm units is the sum of the first two numbers on the frame. So if you have frames that are 53-15-140, the PD of the frame is 53 + 15 = 68mm. In general, you’ll do better with frames that are close to your actual PD: your eyes will be centered in the frames, and the lenses will be centered in the frame too.<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/3</ref>
==From the blog==
[https://endmyopia.org/how-to-measure-pd-pupillary-distance/ Headaches & Fatigue: Measure Your Pupillary Distance (PD)]
==Citations==

[[Category:Articles]]

Pupillary Distance

2022-05-31T08:17:48Z

Gene Onco: Make phrasings more lucid

Pupillary Distance (PD) is the distance between your pupil centers. This measurement is important when ordering glasses to make sure you are looking through the optical centers of your lenses. If you have glasses made by an [[optician]] they may take additional measurements, but those require the frame to be on your face, and standard values are used by online glasses suppliers for those measurements. This is fine for most people, but may be a source of discomfort for some.
Preferably do not use a single number for PD, use the separate distances for each eye measured to centre of the bridge of nose: many people are not perfectly symmetric"<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/4?</ref>

==Near PD==
Because your eyes [[converge]] when looking at nearby objects, your PD is going to be smaller when doing [[near work]] than for [[distance vision]]. If you are buying [[differentials]] or [[reading glasses]] your near PD should therefore be used.

==Pupillary Distance and Frames==
"It also helps if you figure out what size frames fit your head. One trick I read online is the PD of the frames themselves is the first two number on the frame added (so if you have frames that are 53-15-140) the PD of the frame itself is 68mm, so in general you’ll do better with frames that are close to your actual PD (your eyes will be centered in the frames, and the lenses will be centered in the frame too.)"<ref>https://community.endmyopia.org/t/just-encountered-jake-steiner-but-started-myopia-reversal-almost-2-years-ago/14954/3</ref>

==From the blog==
[https://endmyopia.org/how-to-measure-pd-pupillary-distance/ Headaches & Fatigue: Measure Your Pupillary Distance (PD)]
==Citations==

[[Category:Articles]]

Severe myopia

2022-05-29T17:27:10Z

Gene Onco: Link to thickness calculator hosted by the dark side

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge. You can determine how thick the lenses will get if you know all the parameters using [https://opticampus.opti.vision/tools/thickness.php this handy thickness calculator].

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes when looking straight ahead. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T17:11:16Z

Gene Onco: Add missing pertinent conditional

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes when looking straight ahead. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T17:08:01Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature between the front and back surface of the lens, and the thicker the edge.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]], the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T17:00:51Z

Gene Onco: Add link to pupillary distance page

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower ''n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your [[Pupillary Distance|pupillary distance]] , the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T16:39:17Z

Gene Onco: Fix typo

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weighs more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower 'n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T16:35:05Z

Gene Onco: Improve phrasing

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass therefore reduces the thickness of the lens edges and thereby significantly lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: leaded glass weight more per unit volume.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower 'n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T16:32:14Z

Gene Onco: Add some links and polish

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around $300 each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need [https://en.wikipedia.org/wiki/Anti-reflective_coating anti-reflective coatings], but these do not reduce reflections as much as they do for lower 'n'' glass.
* [https://en.wikipedia.org/wiki/Chromatic_aberration Chromatic aberration] is worse since leaded glass has significantly more [https://en.wikipedia.org/wiki/Dispersion_(optics) dispersion] than regular glass. This is particularly noticeable when looking off to the side through the lenses, close to their edges, at a multi-color target such as an RGB LED.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Frequently Asked Questions/Glasses

2022-05-29T13:11:28Z

Gene Onco: Add answer to question on dealing with heavy glasses

{{FAQ boxes}}

==Buying glasses==
====Where should I buy glasses online?====
See [[:Category:Lens seller]].

Blog post: [https://endmyopia.org/best-place-buy-glasses-online/ Where Is The Best Place To Buy Glasses Online?]

====How do I measure pupillary distance?====
[[Zenni Optical]] has a great article on this. [https://www.zennioptical.com/measuring-pd-infographic Find that here]
====Are polycarbonate lenses bad for your eyes?====
The fact that they are polycarbonate makes no difference to your eyes.

Blog post: [https://endmyopia.org/eye-uses-chromatic-aberration-to-guide-axial-change/ Polycarbonate Lenses – Bad For Your Eyes?]
====Why can't I purchase glasses without a prescription?====
Because the industry doesn't want you to have control or understanding about anything that's happening to your eyes.

Blog post: [https://endmyopia.org/never-measure-myopia/ Do. Not. Measure. Your. Eyesight.]
==How do I read my prescription?==

See the [[Guide:Reading_glasses_prescriptions|Wiki guide to reading glasses prescriptions]]

==How do I measure my PD? (pupillary distance)==
{{main|Pupillary distance}}
Blog post: [https://endmyopia.org/how-to-measure-pd-pupillary-distance/ Headaches & Fatigue: Measure Your Pupillary Distance (PD)]

==Why are my glasses giving me a headache?==
When myopia increases, people's headaches tend to get worse. This is largely due to the shrinking field of view higher [[diopter]] correction gives. There's a huge amount of variation in general in this area. It's safe to say though, the higher your diopters, the worse the headaches.

{{jake says|Short answer: You have the wrong prescription!

But, you say, the optometrist says I’ll get used to it. Still, your headache isn’t imaginary, and you didn’t have it before you put on those glasses. What does that tell us? The optometrist is, simply, wrong!

I’ll show you how you can measure your own eyesight, and explain exactly what causes the headaches, in this post: https://endmyopia.org/headaches-because-of-glasses-the-fix-might-be-simple/}}
==My glasses are too thick and heavy, what do do?==
You probably have high or severe myopia. See the [[severe myopia]] page for guidance on selecting lighter-weight glasses.

==Test lens kits==
===Do I need a test lens kit?===
'''No''', generally you don't need a test lens kit. It may be helpful if your myopia is particularly complicated. Most people don't buy a test lens kit and do fine.
===How do you use a test lens kit?===
[[File:Trial test lens kit.jpg|right]]
You insert the lenses from the kit into the really dorky-looking glasses. This way you can test different lenses and how they work.

You can find optometrist approved guides on how to use a test lens kit [https://www.youtube.com/results?search_query=subjective+refraction+ian+squire here].
{{clear}}
===Where can I buy an optometrist test lens kit?===
{{jake says|If you want to check your prescription strength needs at home, you probably want a test lens kit. While this isn’t completely necessary for most people, you might opt to invest in a test lens kit for yourself.

There are a lot of places to buy test lens kits. They range from a few hundred dollars to thousands, depending on the quality and the sales outlet.

Here is an article on what to look out for, and suggestions on where to look for kits as cheap as USD100: https://endmyopia.org/where-to-buy-a-test-lens-kit/}}

==Plus lenses==
===How do plus lenses work?===
{{main article|Plus lenses}}
Plus lenses make you '''more short-sighted, not less'''. They are for the most part useless when it comes to improving [[myopia]].
===Should I use plus lenses to improve eyesight?===
{{jake says|I have mixed opinions about the use of plus lenses. A recent forum reply sums them up fairly well:

I’m not a huge proponent of plus in general. For kids and prevention, yes. For professionals who need insane distance vision, yes. For those who need a lot of stimulus to make progress, yes.

Generally, for the large majority of myopes, with the standard lifestyle (lots of close-up at work, not much outdoor time, a lot of playing on smartphones and TV), not so much. If you’re just looking for 20/20, not needing glasses in generally all conditions, it’s just not a necessary component in a lot of cases.

He says, adjusting his plus lenses while writing this post. ?

Plus is one of those things that’s got as many downsides as potential benefits. If you’re headed towards presbyopia, plus is risky business. You might substitute plus close-up for an extra hour of outdoor time, the latter of which would be more beneficial and give you better than equal results compared to plus use. But knowing you can just grab plus and work another hour, I’m not the biggest fan of. It’s also more lenses, which I generally like to get away from when there are natural focal plane alternatives. The whole thing of where we love to reach for some kind of tech, a product, a “solution”, I try to limit that reflex. Instead find that internal space, taking that breath, accepting a real world, appreciating it (ommm shanti, Jake). You want that good vision to go see good things.

If you like the plus, you’re getting stimulus, use it. If it’s experimenting, you like to try something new, it’s cool and curious, by all means. Use it. Above is just a bit of additional perspective.

As always, don’t go monkeying with lenses, unless you really know what you’re doing. An open minded (and actual science minded) optometrist is always a potentially handy guide in this process.

Semi-related, some thoughts on "plus lens therapy": {{#ev:youtube|X4k30dbjSc0|300|inline}}

''For those who get all huffy when I poke at plus lens therapy: It’s all not to say that plus lenses are bad. It’s just potentially misleading to refer to a focal plane stimulus based approach by a specific lens type. Great way to confuse people, and it’s also far too lens-centric of a thought process to make me feel comfortable. What helps your eyesight is strain reduction and positive stimulus. The kind of lens you may or may not need for this, secondary (and different for one person to the next).''}}

==Diopters==
=====What should I reduce to?=====
See [[Guide:Reducing your correction]].
=====Is it ok to use several different diopter glasses?=====
Generally, you want one pair of [[normalized]], and one pair of [[differentials]]. You can wear more correction when doing important things such as driving at night - very important to do this safely.

==Should I stop wearing glasses?==
'''No''', unless you have [[low myopia]]. See [[Explainer:Should I stop wearing glasses?]]
===I have low myopia. Can I stop wearing my glasses?===
If you have below 2 diopters of myopia, you can definitely look at not wearing glasses any more.

Blog post: [https://endmyopia.org/low-myopia-when-can-you-stop-wearing-glasses/ Low Myopia: When Can I Stop Wearing Glasses?]

==Contact lenses==
===Should I use glasses or contact lenses for close-up?===
You can wear [[contact lenses]] with [[plus lenses]] to achieve the same effect as a pair of [[differentials]]. It's generally preferable to wear glasses in general, but people have managed to improve their eyesight with contact lenses.

{{jake says|(In particular for high myopes, these considerations.)

The tradeoff with glasses over contact lenses (for close-up use) is:

1) Cost (you’re going through a lot of lenses coming down from high myopia, and some people prefer higher index which is also more expensive).

2) Field of vision and image quality. Less of an issue for close-up, but you are going to get less visual quality from a high diopter lens than a high diopter contact lens (in most cases, though you can get somewhat closer with some very high quality, high index lenses).

3) Convenience. You can easily get some replacement contact lenses, experiment with them for reduced diopters. You can easily put a plus lens over contacts for immediate close-up and not carrying two pairs of glasses.

All in all though, I often suggest going with glasses. High diopter contact lenses are thicker, less gas permeable, and tend to cause more corneal abrasion. They disrupt tear fluid. While it always depends on the individual, it’s important to be aware of and consider all of these factors. }}

==How do I calculate math related to optics?==
See [[optics related math]] for more information.
==Can you get better than 20/20 vision?==
{{jake says|If you’re already down to low myopia (1 diopter or less), then it might be time to start thinking about the benefits of going beyond 20/20 – into the single digits of 20/x.

Better night vision, incredible distance vision, reduced risk of recurring myopia, all things you probably want. [https://endmyopia.org/20x-2020-is-just-the-beginning/ Read this post for more.]}}
==Is it OK to use several different diopter glasses?==
Blog post: [https://endmyopia.org/qa-too-many-focal-plane-changes-whats-this-double-vision/ Q&A: Too Many Focal Plane Changes + What’s This Double Vision?]
==How do I reduce prescription complexity?==
{{jake says|Your prescription currently likely includes spherical, cylinder, and axis correction. These numbers aren’t probably even all the same, for both eyes. That’s prescription complexity, and it’s often not good for you, and likely not even necessary!

For the whole detailed explanation of how to reduce prescription complexity, visit this post: https://endmyopia.org/pro-topic-how-to-reduce-prescription-complexity/}}
==See also==
From the blog: [https://endmyopia.org/everything-in-one-place-the-big-primer-on-lenses-and-cost/ The Big Primer On Buying Lenses (And Cost!)]

Severe myopia

2022-05-29T12:58:05Z

Gene Onco: Clarify phrasing

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing a frame with really small diameter lenses, and adjusting the nose pads and ear hooks to position the lenses closer to your eyeballs than you would be able to with larger diameter frames: these won't fit between your eyebrow ridge and cheek bones. The practical limit on how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Myopia

2022-05-29T12:44:11Z

Gene Onco: Reference severe myopia page

'''Myopia''', also known as '''near-sightedness''' or '''short-sightedness''', is a refractive state where distant objects at infinity focus in front of the [[retina]]. This generally causes distant objects to appear [[blur]]ry, while close objects appear clear with [[accommodation]]. This occurs because of a mismatch between the [[axial length]] and the focusing power of the visual system, causing the image of an object. Someone who has myopia is called a '''myope'''.

==Low Myopia==
Low Myopia is short-sightedness in the range of -3 dpt or below. Most people who develop Myopia throughout their lifetimes are prescribed with glasses in the Low Myopia range initially at around -1 dpt after experiencing [[Pseudomyopia]].

===Zero differentials===
The same basic principles for reversing [[Lens-induced myopia]] apply for all ranges of myopia, however below -2 to -1.5 dpt usually no glasses are needed for [[close-up]] work. This means that improvement might slow down because positive [[stimulus]] can only come from [[Distance Vision]], unless [[plus lenses]] are used.

===Very low myopia===
Instead of reducing from -1.5, -1.25, or -1 (based on personal preference), the current EM strategy is to alternate zero and normalized correction, which is a variation of [[zero diopter reset]].

==Moderate Myopia==
Definitions vary, but -2 or -3 to -5 or -6 is considered moderate myopia.

==High Myopia==
Definitions vary, but more than -5 or -6 diopters is considered high myopia. This category has a higher risk of various eye diseases and should be particularly regular about getting exams from an [[optometrist]] or ophthalmologist. If your myopia is even worse, see the [[severe myopia]] page for guidance.

Very few people have high myopia for genetic reasons. Most people who have high myopia had gradually-increasing [[lens-induced myopia]].

==Translations==
This guide has been translated to Polish. See [[EndMyopia Translated]]

==References==
{{reflist}}

[[Category:Articles]]
[[Category:Eye conditions]]

Severe myopia

2022-05-29T12:28:46Z

Gene Onco: Add bit on vertex distance variation

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your glasses up your nose a bit can bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you must take into account when doing the End Myopia program. The vertex distance can change markedly depending on the design and adjustment of your frames.

Severe myopia

2022-05-29T12:16:02Z

Gene Onco: Remove superfluous 'but''

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. For glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-29T12:14:35Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Avoid heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly from the side. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-29T12:11:15Z

Gene Onco: Make phrasing clearer

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker edges on the left and right side of the lenses. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-29T12:08:53Z

Gene Onco: Rewrite refractive index section

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.
==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for high-''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:
* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.
* High refractive index glass is subject to much stronger reflections at the glass/air interfaces. You really need anti-reflection coatings. But these don't reduce reflections as much as they do for regular glass.
* Chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the lens diameter—and of course the stronger the lenses—the more necessary it becomes to keep the weight down and edge thickness under control by paying for the highest-''n'' lenses you can get.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker lens edges on the leftmost and rightmost sides. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-29T11:56:43Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.
==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high refractive index===
The higher the [https://en.wikipedia.org/wiki/Refractive_index refractive index] (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. Opting for ''n'' glass reduces the thickness of the lens edges and lowers the volume of the glass in the lens. This reduces weight, but less so than the volume reduction because the high refractive index is achieved by admixing lead in the glass[https://en.wikipedia.org/wiki/Lead_glass]: which makes the glass denser.

There are disadvantages:

* Cost: Zeiss goes up to ''n''=1.9, but these lenses can cost around 250$ each at an optometrist.

* High refractive index glass is subject to much stronger specular reflections at the glass/air interface.
Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.
When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker lens edges on the leftmost and rightmost sides. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-28T08:45:45Z

Gene Onco: Add some variation to the section headings

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.
==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Opt for lenses with a high index of diffraction===

The higher the index of diffraction (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Prefer round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker lens edges on the leftmost and rightmost sides. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-28T08:42:41Z

Gene Onco: Move sentence to proper paragraph and make more succinct

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.
==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Pick round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker lens edges on the leftmost and rightmost sides. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones. The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the lenses.

As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-28T08:22:19Z

Gene Onco: Finish bit of vertex distance

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. As a severe myope, you probably also spent much time with your nose in books or too close to a screen, landing you on the extreme end of the myopia spectrum.

Basically, your eyeballs are now egg-shaped. Stop being an egg head. Grow some balls. Reverse direction. Do the End Myopia program.

With severe myopia, there are some complications to be mindful of. This page explains them and provides you with guidance.
==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when retinal detachment does happen, fast intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortably heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction (''n''), the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame perfectly matches your pupillary distance, the optical axis of the lenses will be right in the middle between the rims of the frame. This minimizes the thickness of the edges, and hence weight.

===Pick round or oval frames===
With the optical axes of your eyes nicely centered in a frame, round frames result in a constant thickness of the lens edge since all of the edge is at the same distance from the optical axis. This means that round lenses minimize thickness and hence weight for a given field of view.

You probably want a bit more field of view horizontally than vertically, which makes oval frames a good compromise at the cost of thicker lens edges on the leftmost and rightmost sides. Avoid rectangular frames since the corners of the rectangles will be relatively far from the optical axis, making the lens edges there unnecessarily thick, ugly, and heavy.

==View compression and accounting for vertex distance==
Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your minus glasses away from and back towards your eyeballs, and the view compression effect will be apparent.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks be adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames as these won't fit between your eyebrow ridge and cheek bones.

The practical limit of how deep you can place small-diameter lenses is reached when your eye lashes brush against the inside of the lenses.
As a severe myope, you probably learned that pushing your frames up your nose a bit will bring distant objects into better focus. This is because moving a minus lens closer to your eyeball increases its effective strength. Read the page on [[vertex distance]] to learn the details. For high-strength minus lenses, this results in a significant vertex distance correction that you have to take into account when doing the End Myopia program.

Severe myopia

2022-05-28T08:07:04Z

Gene Onco:

Severe myopia

2022-05-27T23:28:24Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina—which is the light-sensing membrane at the back of the eye—becomes more tensioned. For severe myopes, the risk of retinal detachment is therefore markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T23:22:49Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you have found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the larger the diameter, the more necessary it becomes to keep weight and edges under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T23:21:28Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower ''n'' glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for ''n''=1.7 or ''n''=1.8 might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T23:15:11Z

Gene Onco:

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-**n** lenses are expensive: Zeiss goes up to **n**=1.9, but these are much more costly than lower **n** glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for **n**=1.7 or **n**=1.8 might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T23:12:02Z

Gene Onco: Fix typo

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note though that small diameter lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower **n** glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for n=**1.7** or n=**1.8** might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T23:10:20Z

Gene Onco: Add view compression sectoin

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note that small diameters lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, but these are much more costly than lower **n** glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for n=**1.7** or n=**1.8** might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges, and hence weight.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away from and back towards your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs than you would be able to with larger diameter frames.

Severe myopia

2022-05-27T22:59:18Z

Gene Onco: Add section on view compression

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==
As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==
The front of minus lenses is flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===
The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note that small diameters lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, and these are much more costly than lower **n** glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for n=**1.7** or n=**1.8** might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges.

==View compression==

Strong minus glasses significantly compress objects in your field of view such that they appear smaller. The closer the lenses are to your eyeballs, the less compression happens. Try it: move your glasses away and toward your eyeballs, and the effect will be readily apparent, at least if you are a severe myope.

When the lenses sit on your eyeballs, view compression is absent. This is the case when you wear contact lenses. But for glasses you can get some of this benefit by choosing frames with really small diameter lenses and having the nose pads and ear hooks adjusted to pull the frames closer to your eyeballs there where larger diameter frames would have the lenses touch your face when pulled in that close.

Severe myopia

2022-05-27T22:44:54Z

Gene Onco: Guidance for dealing with severe myopia

Minus eight diopters? Minus ten? Worse? No doubt you have been on the receiving end of a long series of ever stronger prescriptions from your optometrist or eye doctor. Reverse direction! Do the End Myopia program.

But severe myopia requires you to be mindful about some additional issues. This page explains them and provides you with guidance.

==Retinal detachment==

As your eyeballs elongate with increasing myopia, the retina, which is the light-sensing membrane at the back of the eye becomes more tensioned and is at higher risk of detaching from the eyeball. For severe myopes, the risk of retinal detachment is markedly elevated[https://en.wikipedia.org/wiki/Retinal_detachment]. All the more reason to reverse direction.

Learn to recognize the symptoms[https://www.nhs.uk/conditions/detached-retina-retinal-detachment/]: when it does happen, intervention and treatment can rescue you from losing sight in an eye.

==Heavy glasses==

The front of minus lenses are flatter than the back, which is curved more strongly. In the center, minus lenses are typically only about 1.5mm thick (thinner would make the lenses too fragile), but moving away from the center (optical axis) the glass becomes thicker. The more minus the diopters, the larger the difference in curvature, and the thicker the edge of the lenses.

When choosing a normal frame with regular diameter lenses, you will end up with very thick lens edges and hence uncomfortable heavy glasses that easily slide off your nose and look ugly. What to do?

===Choose frames with small-diameter lenses===

The smaller the diameter of the lenses once they are cut to fit the frame, the thinner the edges and lower the weight. Such frames are not considered very fashionable, and hence can be hard to find. But with severe myopia, the aesthetic and weight inconvenience of very thick edges make frames with small-diameter lenses very desirable.

Note that small diameters lenses clip your field of view.

===Pick lenses with a high index of diffraction===

The higher the index of diffraction, the smaller the difference in front-back curvature needs to be for a lens to reach a given minus strength. And hence the lower the volume of the glass in the lenses and the weight. Unfortunately, such high-''n'' lenses are expensive: Zeiss goes up to ''n''=1.9, and these are much more costly than lower **n** glasses. Don't skimp on the anti reflection coatings: the higher the index of diffraction, stronger the specular reflection without coating.

When you found a frame with very small diameter lenses, going for n=**1.7** or n=**1.8** might be good enough to keep the weight down and the edges thin. But the large the diameter, the more necessary it becomes to keep things under control with high-index glass.

Beware, high index glass is achieved by admixing lead. Hence the glass is denser and the weight savings somewhat less than the decrease in volume would suggest. Moreover, chromatic aberrations are markedly worse with highly leaded glass[https://en.wikipedia.org/wiki/Chromatic_aberration]. This becomes particularly noticeable when looking off to the side through the lenses, close to their edges.

===Pick frames with a well-matching pupillary distance===
Lenses are cut to fit the frame such that their optical axis (the thinnest part of a minus lens) sits right in front of the pupil of each of your eyes. If the frame matches your pupillary distance, this will have the optical axis right in the middle of the rims of the frame, which minimizes the thickness of the edges.