Is active focus still used once one reaches 20/20?

I was browsing some other threads on here and reading questions and answers, and it made me think of a new one. Since it’s been so long since I’ve had 20/20 vision, I was wondering whether people still use active focus (either instinctually from habit, or to help clear vision) once they reach 20/20 and no longer wear any distance lenses, ever.

I remember Bates talking about “central fixation”, which I’m pretty certain was actually his term for, and way of describing the concept of “active focus” (which I much prefer as a term, as it’s more intuitive than “central fixation”). And his position on it was that everyone with good vision uses it, and that it was protective against myopia.

Dr. Orfield described it using the psychophysical term “JND” (just noticeable difference), and concepts of timed convergence and focusing, which allowed the eyes to focus accurately and clear an image at distance. “Peripheral awareness” (where you’re not attending to explicitly, but are still aware of, the periphery) was also a key component of it for her explanation. She, too, felt this was all a prerequisite of good, “functional” distance vision.

That these concepts keep coming up in all of these sources, means they’re the keys. They’re all the same thing viewed from different angles, in any case, and all of these practitioners have come to similar conclusions that active focus and its many cousins are necessary for both improving and maintaining excellent distance vision. Some would argue for reading or near vision, too.

So, for those who have reached 20/20 and entirely discontinued lens use, do you still use active focus? If so, how, when, and what does it “feel” or “look” like, versus the way you used to do it with lenses on?

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AF is possible only when you have some blur or double vision. the ciliary muscle was here even when you had 20-20 vision so yes it can be in action on 20-20 but only when your eyes are in some trouble.

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AF is something that becomes a habit. At the lower range of myopia it’s more about clearing double/misaligned vision. This is also something that happens subconsciously.

20/20 is pretty darn good vision, however, the real goal is to become emmetropic once more. This will entail you being able to see clear all the way to infinity, you just can’t make out what it is at the far end because it’s just too small. It’ll also make it possible to see perfectly at night, no need for any correction ever anymore.

Getting back to your question, AF (or more appropriately), clearing up and accommodating is something that will continue if you’ll let it. Making it possible for you to get to 20/13 or something and making you truly emmetropic once more. You just have to keep working on the end of your diopter bubble and clear stuff up in that distance.

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20/20 is just the beginning , you can improve more like 20/10 or something…

20/20 is just the measure , at what glasses are not required for distance

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Wow, this is really cool! Thanks for all the replies so far. Very interesting ideas.

For me personally, I remember 20/20 vision and how it looked roughly, but it’s been so long I don’t remember how it felt, etc. The last time I was 20/20 was probably kindergarten! I do know that objects did not appear smaller than normal like they do through minus lenses, and distances were not visually compressed, either…the depth was amazing. I’ve recovered a good level of it already, but not 100%. And of course, I still have a relative ton of blur, being over -3 at this time (though nowhere near as bad as it was at -5). If I don’t have my glasses at night, forget it…can’t see that well!

Even when I get to the point where I only need glasses at night for driving, I will be happy. But I guess even at that point, there’s a lot more progress still to be made!

Another thought - we’re outside, trying to clear up text. Assume that there was no more blur. Would we be looking intently at text to make it clear? No, we would look around at the landscape, at colors, at things interesting to see. Text, at that point of 20/20, would act more as a check on ciliary spasm than as a stimulus to improve.

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In that case, if the person had gone past emmetropia and were slightly farsighted, it sounds like they would be using a form of active focus at distance. I wonder if the refractive state would stay like that, or if needing to use accommodation at distance would drive them back toward emmetropia or even slight myopia over time. If they were truly emmetropic, or just the slightest bit myopic (say, 0.1D) they should have 20/20 or better distance with no strain in theory, I would think.

This actually brings up a bunch more questions…

What is the best outcome as far as refractive state in the end?
-Many would say 0.00, or emmetropia. But the truth is, few are actually 0.00. it’s incredibly rare (looking at data, not just saying). I once got to look at a lot of data on refractive states (1,000 or so), and almost no one measured 0.00 in either subjective refractions, or autorefractor readings (which we know are suspect). Low myopia and very slight hyperopia seemed to be the most common states…+0.25 to even +0.75, was extremely common, and so was the low myopic range of -0.5 to -1. So, there are actually very few truly emmetropic people out there walking around. most of these people had vision in the range of 20/20 to 20/40, and did not wear glasses. A few had 20/15, and one or two were better than that. 0.00 and even -0.25 was pretty rare.

This makes one wonder what the best outcome would be for someone who formerly had multi-diopter myopia. Personally, I think I’d be satisfied once I got below -0.75, and I would probably have 20/20 in good light at that point judging by my history.

@Varakari, the higher order aberrations are a consideration, too. I’ve heard that myopic eyes tend to have more spherical aberration by nature. But, that spherical aberration is not necessarily bad…a bit of it can supposedly help someone clear text at near better if they’re presbyopic, for example. Obviously the surgeons want to be able to control for these things, but is it really realistic to cancel out all aberrations when some help the eye focus? It’s possible that the sign of spherical or chromatic aberrations might be used like the sign of the spherical defocus to help the eye-brain system figure out which way to focus, for example. If those are cues, and you remove them all and create artificially perfect vision, what happens to the system??

Without presbyopia, low hyperopia is not much of a condition. From +0.17 at the optometrist (remember the test distance) to whatever your accommodation can counter, there need not be any symptoms. So most slight hyperopes are perfectly healthy. Presbyopia is not a concern evolution selects against very much.

As for what is optimal under modern conditions, I’d say something between +0.25 and -0.75, depending on how you want to use your eyes. -0.75 is often regarded as the border to emmetropia, which isn’t such a bad choice.

When you’re presbyopic, spherical is always a trade-off. Without enough accommodative amplitude, the eye can only focus at a very small range of distances. At that point, it’s good to have the eye adjusted to a distance that’s useful, which could be anywhere in the emmetropia or low myopia range, so you can at least go without glasses at one distance.

Surgeons modifying the eye will watch out for short-term issues. As for long-term issues and messing with the visually guided adaptation… well, nobody understands that stuff, so… should we could call it “monkeying with lasers?”

I guess time will tell, if someone unbiased does statistics on it. But I’m not confident that this will happen any time soon.

I like that take-off on “monkeying with lenses”!
@jakey

I hope to hit the border between low myopia and emmetropia in about 10 years or so, if I do everything right. We’re talking -0.37D or so. Ten years because that last diopter or so takes a long time…years in some cases. That would be a huge milestone, and glasses basically would in theory almost never be required for distance at that point, even for most night driving.

I have a feeling though, that it’s probably unrealistic, at least for me personally, to never need glasses again. Given my history, and even some very limited use of low plus now, I don’t think I’ll ever totally get away from lenses. But that’s ok. Drastically reducing the power and amount of time spent using them is fine, as well as drastically increasing the quality of vision.

I understand that 20 feet/6m corresponds to 0.17D, but I’m having trouble understanding where the hyperopic defocus of that amount comes from. If you’re refracted at that distance (and not all exam rooms are!) won’t you be using 0.17D of accommodation in theory during the refraction? Do you mean that even someone with presbyopia should/should not be able to accommodate by that amount and it’s not a big deal in either case, or something else? Can you please clarify? Thanks!

Not sure what you are talking about. An emmetrope doesn’t have significant amounts of defocus where the eye doesn’t want it. They can focus wherever they like by accommodating accordingly.

So?

My point is that without presbyopia, nobody cares. If you have 5 dpt of accommodative amplitude, the difference between +0 and +1 to horizon is that your near range ends at 25 cm instead of 20 cm. So unless you want to hold a smartphone or book this close, it doesn’t matter.

In stone age, this was a non-issue. There wasn’t much need to examine things at such low distances. And as you say, these “technically hyperopic” emmetropes have really low refractive error, usually well below one diopter. These low amounts of plus can serve as a safety buffer, and until presbyopia, which evolution isn’t too interested in, that can work just fine.

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I agree 100%. Thanks for explaining what you meant.

It’s crazy, but I’ve seen refraction manuals claiming the clinician should add -0.25D to the subjective endpoint in a 12 foot room that uses a mirror system (designed to optically put the chart at 20 feet). I never understood that one, one bit.

Unless the walls are causing accommodation, why would they do that?

I could see doing so without a mirror in a smaller room, maybe. But there are so many other factors that might lead to overminusing, so why would they go down this road and risk adding even more negative bias? Some refractionists I’ve talked to say they don’t do it but technically you should.

These same manuals say the clinician should make it clear that a smaller image with better contrast is not the goal…only readability. I know few optometrists who even tell their patients this, but all of them should. Or at least the patient should go in knowing it.

And as far as autorefractions, every time I’ve had one, the final image has been ridiculously crisp and flat. I would not want glasses that made everything look like that. I imagine the light coming from infinity would have to focus at about 2 feet in front of my eyes optically (on top of full distance correction) to make things that crisp. I can actually somewhat see the pixels in the printed target by the end.