Difference between revisions of Differentials
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[[File:Microsoft Cloud Event Dublin, upclose with graphs.jpg|thumb|Without ''differentials'', you're on the path to ever increasing prescriptions and will get nowhere with vision improvement :(]] | [[File:Microsoft Cloud Event Dublin, upclose with graphs.jpg|thumb|Without ''differentials'', you're on the path to ever increasing prescriptions and will get nowhere with vision improvement :(]] | ||
'''Differentials'''([[EM:JARGON|jargon]]), (''close up'', ''computer use'' or ''diffs'') are reduced strength glasses or lenses for [[close-up|close up activity]]. They have a lower correction than your [[normalized]] lenses, the difference between them | '''Differentials''' ([[EM:JARGON|jargon]]), (''close up'', ''computer use'' or ''diffs'') are reduced strength glasses or lenses for [[close-up|close up activity]]. They have a lower correction than your [[normalized]] lenses, the difference between them being usually between 1 and 2 [[diopters]].<ref>{{cite jake|https://endmyopia.org/faq-items/what-is-the-differential-prescription/|What is the differential prescription?}}</ref><ref name=ChooseReduction>{{cite jake|https://endmyopia.org/choose-reduced-glasses-prescription-differential-close-friendly-glasses/|How To Choose A Reduced Glasses Prescription (Differential / Close-Up Friendly Glasses)}}</ref> | ||
==Low Myopia== | ==Low Myopia== | ||
People with myopia of -2 D and lower do not typically need to wear differentials (because with -2 D your distance till blur should be around | People with myopia of -2 D and lower do not typically need to wear differentials (because with -2 D your distance till blur should be around 50 cm - far enough to see your screen with sufficient clarity). The exception being that if you have more than 1 diopter of cylinder correction you will likely need differentials to help manage directional blur. In this event you likely can reduce the cylinder correction by between .25 and .75 D and pair it with a reduction of up to 1.25 D in spherical strength for either little or no spherical (plano) correction. | ||
==First Differentials== | ==First Differentials== | ||
The first differentials are typically 1. | The first differentials are typically 1.5 D weaker than your [[measurement]] for full distance vision. If you have -0.25 to -0.75 D of cylinder, you have the option of dropping that and having the sphere only 1.25 D weaker. | ||
See [[Lens#How to use Contacts with EM|How to use Contacts with EM]] if you wear contacts. | See [[Lens#How to use Contacts with EM|How to use Contacts with EM]] if you wear contacts. | ||
==Adjusting Differentials== | ==Adjusting Differentials== | ||
Ideally your differentials give you a small amount of blur at your daily near work. The nature of your work, the distance to your work, and your [[refractive state]] and [[cylinder]] dependence are all factors in choosing your differentials. The ideal distance for near work is not closer than | Ideally your differentials give you a small amount of blur at your daily near work. The nature of your work, the distance to your work, and your [[refractive state]] and [[cylinder]] dependence are all factors in choosing your differentials. The ideal distance for near work is not closer than 50 cm. You may get your first differentials and discover you have a headache and you really shouldn't have dropped cylinder. You may find that your work is pretty close or really far and you need to adjust the strength up or down. You may find that you really need detailed vision to do your work and you'll settle for slowing progression with your differentials and do your blur challenge for improvement in your off hours. This is the first place in the program where you really need to start understanding what you're tinkering with and make personalized diopter specific choices. | ||
==Why are differentials worn?== | ==Why are differentials worn?== | ||
The primary stimulus for [[axial elongation]] of the eyeball is [[hyperopic defocus]], which occurs when someone: | The primary stimulus for [[axial elongation]] of the eyeball is [[hyperopic defocus]], which occurs when someone: | ||
* | * is engaged in close-up activity | ||
* | * wears more correction than needed when seeing the object that is close up. | ||
Differentials allow the wearer to wear ''just what they need to'', to see up close. This removes the stimulus of hyperopic defocus | Differentials allow the wearer to wear ''just what they need to'', to see up close. This removes the stimulus of hyperopic defocus and stops eyes from getting more myopic. In a sense, it's a [[quick fix]]. {{wink}} | ||
It's fairly easy to stop [[ | It's fairly easy to stop [[lens-induced myopia]] from progressing by just wearing differentials. The axial length of the eye does not randomly change by itself; it only changes in response to [[stimulus]]. | ||
Another reason to wear differentials is to avoid [[convergence]] issues. When viewing in close proximity the position of your eyes needs to compensate by turning in, particularly when you are looking nearer than | Another reason to wear differentials is to avoid [[convergence]] issues. When viewing in close proximity the position of your eyes needs to compensate by turning in, particularly when you are looking nearer than 50 cm. Doing this for long periods of time on a regular bases is likely to cause issues. Such issues are easily avoided by wearing differential correction to accommodate a larger distance. | ||
== Habits == | == Habits == | ||
It's useful to apply the [[20-20-20 rule]] when engaging in close up. | It's useful to apply the [[20-20-20 rule]] when engaging in close up. Alternatively a 1-hour period of distance vision following 3 hours of near work can be effective. | ||
Always be mindful to be in a good ergonomic position | Always be mindful to be in a good ergonomic position. Leaning in is a common issue and is something you need to be mindful to avoid. | ||
Good ambient lighting is important | Good ambient lighting is important because your eyes can not see as far or as well in low lighting. Natural light is best but supplement as needed. | ||
== See also == | == See also == | ||
Revision as of 03:16, 15 July 2021
Differentials (jargon), (close up, computer use or diffs) are reduced strength glasses or lenses for close up activity. They have a lower correction than your normalized lenses, the difference between them being usually between 1 and 2 diopters.[1][2]
Low Myopia
People with myopia of -2 D and lower do not typically need to wear differentials (because with -2 D your distance till blur should be around 50 cm - far enough to see your screen with sufficient clarity). The exception being that if you have more than 1 diopter of cylinder correction you will likely need differentials to help manage directional blur. In this event you likely can reduce the cylinder correction by between .25 and .75 D and pair it with a reduction of up to 1.25 D in spherical strength for either little or no spherical (plano) correction.
First Differentials
The first differentials are typically 1.5 D weaker than your measurement for full distance vision. If you have -0.25 to -0.75 D of cylinder, you have the option of dropping that and having the sphere only 1.25 D weaker.
See How to use Contacts with EM if you wear contacts.
Adjusting Differentials
Ideally your differentials give you a small amount of blur at your daily near work. The nature of your work, the distance to your work, and your refractive state and cylinder dependence are all factors in choosing your differentials. The ideal distance for near work is not closer than 50 cm. You may get your first differentials and discover you have a headache and you really shouldn't have dropped cylinder. You may find that your work is pretty close or really far and you need to adjust the strength up or down. You may find that you really need detailed vision to do your work and you'll settle for slowing progression with your differentials and do your blur challenge for improvement in your off hours. This is the first place in the program where you really need to start understanding what you're tinkering with and make personalized diopter specific choices.
Why are differentials worn?
The primary stimulus for axial elongation of the eyeball is hyperopic defocus, which occurs when someone:
- is engaged in close-up activity
- wears more correction than needed when seeing the object that is close up.
Differentials allow the wearer to wear just what they need to, to see up close. This removes the stimulus of hyperopic defocus and stops eyes from getting more myopic. In a sense, it's a quick fix. 
It's fairly easy to stop lens-induced myopia from progressing by just wearing differentials. The axial length of the eye does not randomly change by itself; it only changes in response to stimulus.
Another reason to wear differentials is to avoid convergence issues. When viewing in close proximity the position of your eyes needs to compensate by turning in, particularly when you are looking nearer than 50 cm. Doing this for long periods of time on a regular bases is likely to cause issues. Such issues are easily avoided by wearing differential correction to accommodate a larger distance.
Habits
It's useful to apply the 20-20-20 rule when engaging in close up. Alternatively a 1-hour period of distance vision following 3 hours of near work can be effective.
Always be mindful to be in a good ergonomic position. Leaning in is a common issue and is something you need to be mindful to avoid.
Good ambient lighting is important because your eyes can not see as far or as well in low lighting. Natural light is best but supplement as needed.
See also
References
- ↑ The EndMyopia Blog, https://endmyopia.org/faq-items/what-is-the-differential-prescription/
- ↑ The EndMyopia Blog, https://endmyopia.org/choose-reduced-glasses-prescription-differential-close-friendly-glasses/