I wonder if AF can cause negative accommodation

I wonder if clear flashes are due not just to normal active focus and the cortex working well, but the lens actually flattening more than it normally does…beyond the point typically used for distance vision.

I wonder if that is even possible.

This might also account for the rare instances of temporary no-glasses hyperopia or presbyopia-like symptoms and headache from doing too much AF…if the lens got stuck like that for a bit.

Just me rambling…


Interesting question, I also asked myself often when everything outside appeared so extra crisp and clear. I also started from an undercorrection (I was wearing about 0.25-0.50 less than the opto would have given me).
So would be interesting if it‘s actually possible to flatten the lens more than needed or if it‘s just the visual cortex getting used to that level of clarity.


Well, I’m no expert, but I do have a BS in Neuroscience and these things interest me. I wonder if anyone knows for sure.

In my opinion though, there is no way it could just be the brain, the pupil giving more depth of field, good convergence, etc. I mean, you have to get the focus somewhere. There are times when I wear differentials and can see almost perfectly 8 to 10 feet away, and sometimes further.

I do wonder if it’s more the lens or actually the eyeball (probably choroid) a la Dr. Bates, though…

There is definitely “negative relative accommodation” when you look on Google scholar. But I wonder just how far it can go. If it’s like other things in the body, it can probably go beyond the average range at times…

That may also explain how some eye exercise programs (basically through active focus) manage to get people clear flashes that override several diopters of myopia temporarily.

I also still have a feeling this mechanism (and most active focus also) is likely pretty much independent of emmetropization (and by extension myopia reduction, which seems related to emmetropization).


We need to combine some test subjects, measuring equipment, and hanging out at my favorite kite surf beach. Somehow.

And get some federal funding. :grimacing:


@jakey, yes. And nice beach.

Is this a topic you’ve wondered sbout?

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Definitely something to consider :slight_smile:

I will volunteer for this experiment :palm_tree::beach_umbrella::tropical_drink::sunglasses: Everything in the name of science of course.

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I just found this recent Russian study. I don’t understand the whole text as it’s very scientific and English isn’t my mother tongue but I was interested by the last sentence of the conclusion.