Diopter Gap: Number of diopters between your differential and normalized correction.
This one falls squarely into advance topics.
For most people, choosing a differential based on ergonomically comfortable close-up distance from a computer screen, and a differential based on about 20/30 on a Snellen chart, results in a diopter gap of around 1.5 diopters.
Lots of factors can play into the individual diopter gap.
Anything from accommodation range (age), ambient lighting, alternate close-up distances, preferences for distance vision diopter bubble, all can affect your individual diopter gap.
Main thing to consider is that you likely don’t want it to be less than one diopter, and very likely no more than 2 diopters.
Especially when exceeding 2 diopters, you start to have a large diopter gap. Meaning, there is a large amount of your acuity distance not covered by either differential or normalized. Doing so reduces your opportunity for active focus with differentials, and may leave you over corrected in some cases when using your normalized.
There is a bit of a teaser video on diopter gap in our Youtube channel.
If you want to explore the full topic in more detail you’ll either need to have earned a (free) participating member invite to Le Meow, or be a member of (paid) BackTo20/20. I’ve added a long video explaining all the ins and outs of the diopter gap, available to participating members.
Though really all you really need to know is to ideally not exceed 2 diopters, as long as you’re in that range you’re all set.
Housekeeping: You’ll notice that pro topics will no longer always be included in the free blog guides. Since I get so much e-mail, and ungrateful freeloader complaints about the endless free resources I post here, I’ve decided to start requiring either active participation in the community or paid membership to help with some of the more advanced (and optional) topics.
Either way, watch that diopter gap. And contribute to the community, drop me a line if you have ideas to help endmyopia (we can always use posts on other sites, community exchanges, video progress updates, and lots more). Contribute and get more of the available resources.
Most importantly, keep making all the 20/20 gains!