Difference between revisions of Frequently Asked Questions/Myopia
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==Does 20/20 mean perfect eyesight?== | ==Does 20/20 mean perfect eyesight?== | ||
In most cases, an [[optometrist]] will prescribe glasses for 20/20 vision. Optometrists are not perfectly accurate in many aspects ({{awesome}}), and so you might actually have a small amount of [[myopia]] or [[hyperopia]] in reality. | In most cases, an [[optometrist]] will prescribe glasses for 20/20 vision. Optometrists are not perfectly accurate in many aspects ({{awesome}}), and so you might actually have a small amount of [[myopia]] or [[hyperopia]] in reality. In a lot of cases, 20/20 does mean perfect eyesight. It means you can read the 20/20 line on a [[Snellen chart]] without using [[Active Focus]]. | ||
{{jake says|No, 20/20 is definitely not equal to perfect eyesight. | |||
The entire premise, the eye chart, the way your visual acuity is measured, is actually a very, very rough approximation of your eyesight. It’s “good enough” for the mainstream to “prescribe” you lenses, but you should be aware that it’s about as scientifically representative of your vision as a stick figure is of your real person. | |||
Toshiki recently offered a very apt summary of eye chart testing, in the forum: | |||
{{quote|20/20 is just an 1861 approximation of the average visual acuity of a human. Today we know that for adolescents and young adults (up to say 35) it’s nothing unusual to have 20/10 and better vision. It’s just unusual for optometrists/ophthalmologists to actually find 20/10 or better, because… | |||
…the optometrist’s setup with rather poor lighting tends to cut off anything better than 20/15, | |||
…the small distances between symbols that you have for high acuity lines lead to an effect called crowding, which makes anything smaller than 20/15 hard to recognize even for those with 20/8 vision, and finally | |||
…most eye charts stop at 20/13, which is probably a good thing, because otherwise a lot more young folks would be (jay-)walking on the streets staring at their smartphones 15cm in front of their eyes while wearing glasses that give them ants-from-outer-space vision. | |||
Given these facs, I don’t see why getting better than 20/20 vision should require any lenses at all. On good days and with decent lighting, I am now at 20/16 without correction (only left eye, right is still 20/32…20/50).}} | |||
Consider too that many jurisdictions require 20/40 vision for driver’s license exams to be passed without corrective lenses. And if you’re curious, print an eye chart online and compare your vision in shaded outdoor light to results you get with indoor lighting. You might notice dramatic differences! | |||
So what’s 20/20? | |||
20/20 is a barn door. It’ll do, as far as determining a ballpark for your eyesight, and a means to figure out how much lens correction will give you the clearest possible vision. Consider this, the tool used by optometry, and it’s vaguest accuracy, before ‘blindly’ trusting the mainstream lens sales with your eyesight.}} | |||
==What is axial elongation?== | ==What is axial elongation?== | ||
[[Axial elongation]] is the increase in length of the eyeball. It happens when you wear glasses and look at screens for extended periods of time. Specifically, it happens due to [[hyperopic defocus]] as a result of [[close work]] combined with [[glasses]] that are [[overprescribed]] for the [[focal distance]] in question. | [[Axial elongation]] is the increase in length of the eyeball. It happens when you wear glasses and look at screens for extended periods of time. Specifically, it happens due to [[hyperopic defocus]] as a result of [[close work]] combined with [[glasses]] that are [[overprescribed]] for the [[focal distance]] in question. | ||
Revision as of 11:18, 18 June 2020
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| Frequently Frequently Asked Questions (please read this!) |
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| About Myopia | LASIK |
Glasses & diopters |
Mindset | Troubleshooting |
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| Active Focus | Habits | Measurement | Normalized | Differentials | Astigmatism | Other |
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| Skepticism |
About EM | Paid course | Other eyesight conditions |
Ineffective Myopia Treatments |
Does 20/20 mean perfect eyesight?
In most cases, an optometrist will prescribe glasses for 20/20 vision. Optometrists are not perfectly accurate in many aspects (
), and so you might actually have a small amount of myopia or hyperopia in reality. In a lot of cases, 20/20 does mean perfect eyesight. It means you can read the 20/20 line on a Snellen chart without using Active Focus.
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What is axial elongation?
Axial elongation is the increase in length of the eyeball. It happens when you wear glasses and look at screens for extended periods of time. Specifically, it happens due to hyperopic defocus as a result of close work combined with glasses that are overprescribed for the focal distance in question.
How do I calculate all the diopter & optics maths?
See optics related math.
What is pseudomyopia?
Pseudomyopia is where the ciliary muscle locks up due to prolonged periods of close up, typically spent in front of a monitor. Pseudomyopia is typically the condition people have when they first go to the optometrist to get a pair of glasses. That pair of glasses goes onto cause lens-induced myopia.
Why is my eyesight worse indoors or in low light?
Causes of myopia
Does computer work cause myopia?
When you combine prolonged periods of computer work with a pair of distance vision glasses, that correct you more than what you need to see the screen, yes.
Does neglected peripheral vision cause myopia?
No. It's not clear how someone can 'neglect' their peripheral vision, as it's always there.
Is myopia genetic/hereditary?
No, in the majority of cases. The majority of myopia is lens-induced in the world. Question why Wikipedia:natural selection has failed so terribly it's resulted in eye defects in huge swathes of the population, two billion in the world.
The Ministry of Healh in Singapore says: "The prevalence of myopia in Singapore is among the highest in the world, with 65 percent of our children being myopic by Primary 6, and 83 percent of young adults being myopic."/ [1] How did their ancestors survive to lead to the current generation if myopia is generally so disadvantageous to an organism's survival?
Do glasses make my eyes worse?
Yes, when the glasses are for distance and you perform excessive periods of close-up activity.
Potential solutions to myopia
Does outdoor time reduce myopia?
Yes, when combined with a good pair of normalized, Active Focus and your other habits are corrected. It's not that complicated, see The Eyesight Improvement Equation