Pro topic.  Don’t go monkeying around with diopters until you really know what you’re doing.  Messing around with diopter ratio, making focal plane changes, all creates a series of interactions with your visual cortex.  If you don’t know what you’re doing you might at minimum cause unnecessary discomfort – or more negatively, impact your opportunities for future progress.

Quick post today, with just part of a BackTo20/20 forum thread.  

This one highlights how changes (improvements) in your vision that may be unexpected and not just the garden variety 1/4 diopter reduction every 3-4 months.

Use this as a template for how we approach centimeter changes, and adapting diopters accordingly.  Also see how we want to stay ahead by anticipating the type of adaption we’re looking to create with focal plane changes.

The High Diopter Ratio Scenario

Sejal writes:

My first measurements for differentials were 52cm overall. My current measurement? It’s hard to pinpoint differentials by cm because my eyes keep focusing at different rates at different times (does that make sense). So sometimes I get 92cm to 97cm in either left or right eye, but combined it’s 93cm to 100cm.

Can you help me figure out what my next differentials should be?

(Part of a longer post, and much longer thread – if you have BackTo20/20 access, you can find it here.)

Here’s my comment:

Yea, that’s definitely a big ratio. Your improvements have been pretty consistent so it’s a good time try to reduce that ratio a bit. This one is a bit adventurous, especially since you’re reporting inconsistent focus – but the best way to to see how your eyes respond, is to give it a shot:

Right: -2.25
Left: -3.50

This is definitely not the standard reduction. If you go for this one, do it on a weekend or otherwise a few relaxing days with not a whole lot of mandatory close-up. Start without glasses, work on some focus, get some outdoor time, then (without using the old differentials first), spend 30 minutes to an hour with the new ones. Ideally very easy content, printed page, or simple writing on the screen. Ease into it. All this since mainly your visual cortex isn’t going to be expecting this focal plane variance change, and it’ll accept it most readily if we start out with more blur challenge (then any increased sharpness is welcome to the brain), and then don’t make it work too hard when getting the new focal plane.

Make sense?

Of course this isn’t prescription or optometrist advice.  You do what you want to do, Jake is merely pontificating on the whisperings of his magnificent beard.

Also to consider, Sejal’s centimeter log:

Always a good idea, the log. 

Both eyes there, progressing nicely, responding consistently.

When you’re looking at that, consistent improvement, you can add a little bit of a more complex focal plane change to address things like a big diopter ratio.  It’s something you want to do in small doses relative to the binocular changes and only when everything is otherwise smooth sailing.

That’s it!  Go forth, make your own smart decisions about focal planes.

Housekeeping:  If you’re looking for this sort of Jake advice specific advice, find me in the support forum.  I’m opening a few more BackTo20/20 invites per month.  They remain limited since I have to do forum support (like above), which is something I don’t want to spend increasing amounts of time on.  

If you haven’t gotten an invite and wish you had one, e-mail me.  Include details about your case and why you should be in BackTo20/20.