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A movie changed one man's vision (2012) (bbc.com)
43 points by Tomte 75 days ago | hide | past | web | favorite | 18 comments

Personal anecdote: I was born with astigmatism, hypermetropia with over 3 diopters difference between eyes, a slight esotropia, which was partially corrected by training, and have developed amblyopia as the result of all that.

Naturally, I didn't even know about stereo vision, everything was flat and that didn't bother me.

But when I was about 20 years old, my friend showed me Virtual Boy. After looking into the headset I immediately sensed the depth and was blown away with it.

Even after I took off the headset, depth perception didn't go away ever since. It only became much stronger when I started wearing contact lenses.

Sorry for possible grammar mistakes, I haven't yet experienced anything like Virtual Boy but for English, which is not my first language.

People advertise contact lenses as a fashion thing. "No ugly glasses." But the biggest benefit of contact lenses is IMO "no pincushion/barrel distortion". Especially if you need different correction for each eye, it can make a big difference. I think a lot of people who wear glasses don't know you can avoid the distortion with contact lenses.

Glasses have saved my sight in an eye twice. Once was avoidable stupidity (kids are dumb), once was unavoidable. I see them as protective as much as for vision now. I don't want contacts.

One other seriously negative thing about contacts is that unless you are fastidious about cleaning or disposing them you risk eye infections, which could potentially be very serious.

I used to wear disposable lenses, but out of lazyness and frugality, I'd leave them in longer than I should have and suffered multiple eye infections. Fortunately, no serious harm resulted from them, but I recognized the risk and eventually switched back to wearing glasses. Since then I've never had to worry about that stuff ever again.

I've used hard (gas-permeable) lenses for 35 years without problems, but then I take them out every night and clean them. It's not nearly as difficult to keep them clean as it is with soft/disposable ones.

That is probably because you're using something like ClearCare which is a buffered hydrogen peroxide (with some other stuff) and a case that acts as a catalyst. The peroxide sterilizes your contacts, the catalyst slowly converts all the hydrogen peroxide to water. It takes at least 6 hours and you have to change the case out with every new bottle every month or so or else you get hydrogen peroxide in your eyes, which even in small amounts is really awful. I use to use the stuff by choice because it helped my eyes feel more comfortable vs the other contact lens solutions (except for the days I was lazy and didn't change out the cases or over wore my lenses past the X amount of days before disposal). I had soft contacts, that's why it was a choice, but I'm pretty sure hard contacts require the use of this type of cleaning method. Now I use dailies because they're more comfortable even though they're crazy expensive.

You can still wear contacts for improved vision and then wear actual safety glasses that are designed to meet standards for protecting your eyes. Don't rely on the accidental strength of prescription glasses.

They're also much cheaper to replace than prescription glasses when damaged or scratched.

Safety glasses come in many models today - many look like sport sunglasses and come in clear, tinted, yellow, and shaded.

Can contact lenses do cylinder correction nowadays; is there a "this side up"-sort of orientation to them?

Yes, they're called toric lenses: https://en.wikipedia.org/wiki/Toric_lens

I've always been curious if stereoblind people are typically better at drawing than people with normal stereo vision. I'm stereoblind, and I always seemed to be better than most of my peers at drawing, and my hypothesis is that since there are no stereo cues from a flat piece of paper (or rather, what stereo cues there are are "wrong" if you're attempting to draw a 3D scene), the stereoblind person is not going to be bothered by (nor attempt to (incorrectly) render) discrepancies in stereo cues between what they're drawing and what they're seeing.

My sister is a fantastic photographer. She has an incredible ability to look at the entire 3D world around her and discover these little pieces of it that make for an excellent two-dimensional image.

She is also famously clumsy, always tripping, dropping things, bumping into stuff, aiming poorly, etc.

I've often wondered if poor stereo vision is the cause of both of those.

I have normal stereo vision, but I remember struggling for many hours to see random dot autostereograms (e.g. Magic Eye images). And then suddenly I saw the 3D image, and after that I never had trouble seeing them again. I've heard many anecdotes of similar experiences. Maybe there's a similar kind of learning in this case.

A large part of the struggle you experience with these is that you force your eye to do two clashing operations that usually proceed in sync. Among the signals our eyes use to detect depth are:

* Accommodation: Our lenses are flexible. We unconsciously contract the ciliary muscles in our eyes to change the shape of the lens so that it focuses light at different distances. It's very similar to adjusting the focus ring on a camera or binoculars.

* Convergence: As an object moves closer to you, in order for the object to stay centered on the fovea of each eye, your eyes need to turn inwards. To look at something really close, you go cross-eyed. When looking at something far away, your eyes are parallel.

Both of those involve muscular control that also give feedback to your brain. So you can unconsciously feel how much your lenses are accommodating and your eyeballs are converging. Typically, those signals are in sync with each other.

Autostereograms break that. To get the effect, you need to look "through" the picture. When you do, each eye isn't actually centering the same part of the picture on its fovea. That way, each eye gets a slightly different image, and the differences between those two cause a parallax effect that we perceive as depth.

The problem is that as far as accommodation is concerned, the picture is close. The lenses really do need to focus on the picture itself to resolve a sharp image. But for convergence, your eyes need to be closer to parallel as if you were training your eyes on something past the picture.

Now your brain can tell these two things are out of sync and it gets very confused. Some people seem to have an easier time decoupling these things than others do. It ends up a feeling a little like patting your head and rubbing your stomach at the same time.

I have never come to see anything in these dots. I tried multiple times using various viewing tutorials and failed every time.

I hope this does not work the other way - you see stereo, look at a stereogram you are unable to view correctly and boom - you're stereoblind.

"Like many of the 5-10% of the population living with stereoblindness"

What? 5-10% of those with stereoblindness or 5-10% of the general population suffer with this?

5-10% of people are stereoblind

> Like many of the 5-10% of the population living with stereoblindness,

I would have called BS on this, but seems legit, just lacking a bit on nuance


"It is widely thought that about 5% of the population have a lazy eye and lack stereo vision, so it is often supposed that most of the population (95%) have good stereo abilities. We show that this is not the case; 68% have good to excellent stereo (the haves) and 32% have moderate to poor stereo (the have-nots). Why so many people lack good 3-D stereo vision is unclear but it is likely to be neural and reversible."

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