Difference between revisions of Close-up glasses

 

[[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 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>

The first differentials are typically 1.25 - 1.5 D weaker than your [[measurement]] for full distance vision.  If you have -0.25 D of cylinder, you have the option of dropping that.  If you have -0.5 to -0.75 D of cylinder, you have the option of dropping that and having the sphere only 1 - 1.25 D weaker.

See [[Lens#How to use Contacts with EM|How to use Contacts with EM]] if you wear contacts.

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.

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.

Wear your differential glasses any time you are doing close work.  If you have to get up to go to the bathroom, switch back to your normalized glasses.  You get used to it pretty fast. "What if I just need to look out my window for like a minute?" CHANGE YOUR GLASSES.  If you are asking yourself "should I switch to normalized glasses to look outside the [[blur horizon]] of my differential glasses?" the answer is always YES.

'''What is "close" work?'''  Norms minus diffs = the number of diopters you need to convert to find this answer.  For example, if your normalized glasses are -5 and your differential glasses are -3.5, then you need to convert -1.5.  You should be able to see 66.67cm with -1.50 myopia!  That's about 26.24 inches, or a little more than 2 feet.