🎥 Low Myopia, Close-Up Glasses: A Plus Lens Use Case?

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A possible explanation for strange effects of plus lenses could be what’s happening in peripheral vision.

If you’re still beyond -1 and use something like a +0.5 with a huge field of view, and your screen/book is far enough in the “open”, with no nearby obstacles in your periphery, the behavior should be similar as with other near-work glasses.

But if you use something that has more plus than your eyes have minus, your outer periphery, the part outside your glasses’ frame, gets hyperopic defocus all the time.

Edit: it might be confusing why an area without glasses in the way could be affected. But note that your ciliary muscle is controlled by the target you’re looking at, but if the ciliary muscle relaxes, the whole view is affected, periphery included.

To complicate calculations, the common, relatively flat, spherical lenses don’t have even power. Once you’re not looking through the optical center of the glasses, the power changes. This is an issue for strong minus lenses too, but there, things get nicer as you step down the power. When you start going up again with plus lenses, the funky effects get stronger again. Cylinder error depending on your viewing angle, too. But looking only straight is unhealthy, so that’s not an option either.

The eye doesn’t only calibrate axial length, so you might be applying weird higher-order deformations to your eyes from the unnatural situation of simulating an extreme “tunnel view” with the plus glasses, where the outer periphery appears insanely close in terms of focal distance.

So… I think this is a classical case of “don’t monkey with lenses”. It should be possible to make this work, but there could also be a lot of ways to mess up. If this theory is correct, just choosing a narrow frame for the plus glasses could screw you over.

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Did you guys delete the video?

I think your account might need to have enough activity to see the link.

Sorry, new policies, but it won’t be long.

Fixed it - it’s been moved to the pro topic videos (paid members) but I just put this back here to be at least accessible from this page. :smiley:

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What is the difference between +0.25, +0.5, +1, and so on, that would make someone prefer one over the other in fixing low myopia (that pesky last diopter :smiley:)? I’m also not comfortable with the idea of plus lenses and hope to not ever have to use them (unless there is a very strong reason to).