Preface: I am fully sighted but wear glasses. I don't think that this question is insensitive to me, though I worry that it might be insensitive to you. I know from personal experience that it's no good to dwell on impossibilities, and if you truly think that you cannot experience this, then please try not to (metaphorically) beat yourself up about it. Because you asked, I will answer to the best of my ability -- feel free to ask any followup that you want.

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This is an odd question to me because I've done a lot of accessibility work with aids like a blurry screen, removing my glasses, zooming in, or just turning off screens to learn a screen reader, but I've never really thought about vision with one eye.

Stereoscopic vision is important and useful for discerning detail and seeing depth; when I close one eye and look at something that is up close, everything in the background becomes blurry, but still visible and discernible. But if you hold something up to your face with both eyes open, everything in the background is doubled (once for each eye) and your brain just kind of filters it out so you can focus on the object.

To illustrate this, I've done some quick modifications to a stereoscopic image. (Yes, I'm aware of the irony of posting an image set to r/blind.) You can take a look at it here -- https://imgur.com/a/93XgjgO -- but here's the description.

A stereoscopic camera uses two lenses to take two pictures right next to each other in a mimic of how the human eyes are laid out; if you cross your eyes and basically stare into the distance at the picture, there is a certain point where it will look like the two images are overlaid over each other and it tricks your brain into seeing it in 3D, so to speak. In the gallery link above, I've taken a stereoscopic picture of a camera and left it as-is; two pictures from slightly different angles next to each other, but they're both looking at the same thing.

The image under it is where things get interesting; I've overlaid the two images over each other. In the center is the camera, and it's mostly in focus; I attribute the "mostly" part to a combination of the picture being from the 70s and my lousy photo editing skills. As things get farther away from the camera (the part that's in focus), they look duplicated more and more. This is especially noticeable in the rod that comes out from the front of the camera; it starts out at the camera, but then rapidly appears to split apart into two pieces as it gets farther away from the camera. This is how the brain sees depth; we don't really register that we're seeing double of some things, but the _amount_ of "double" that we see tells the brain how far away something is _relative to the thing we're focused on_.

This all happens automatically -- there's no real processing that needs to happen for this to work. Our eyes and brain are extremely sensitive to this phenomenon and it is accurate to very small distances (and works even in peripheral vision)! A real life example is that there is a cup about 4 inches in front of my monitor on my desk. While looking at the center of my monitor, I can reach out and accurately touch the rim of the glass and it's exactly where my brain says it should be in space.

Something that's related to stereoscopic vision but not depth is your NOSE! Your nose is always visible to the eye, but here's something you may not have thought about: it's in _two different places_. In the left eye, your nose is in the bottom right corner, and in your right eye, your nose is in the bottom left corner. That means that your brain automatically filters it out as junk visual data unless you're actively looking for it! If you're looking at something out of the corner of your eye and your nose blocks the way, your brain automatically fills in the blocked piece with information from the other eye, so you still see a complete image.

My last thought is that eyes are freaking weird. (Warning: simplification incoming!) You probably know that there are rods and cones in the eye that detect different colors and that's how our brain puts together the image... but there are no rods and cones in one specific place; the very center of the back of the eyeball. That's where the optic nerve connects to the eyeball, so there's no room there. That means that if you're looking at something with one eye, whatever is in the center of your vision just... disappears. You can compensate for it by looking slightly to the side of the thing you actually want to see, but the brain can fill in that missing information with data from the eye and you'll never notice unless you're intentionally trying to "break" this process. Since you have good vision in one eye, the optical illusion on this page should work for you: http://www.personal.kent.edu/~rmuhamma/OpticalIllusion/illusion.html It also explains a little bit about how the illusion works and how your brain handles that particular bit of weirdness.

I'm sorry for accidentally writing a novel -- I hope this answers your question in an educational and respectful way. As I wrote at the beginning, I'm happy to answer whatever I can. Cheers!

When I had normal vision, it wasn't anything extremely different than what you have right now.You would be able to see a little more to the one side, with your peripheral on that side- but it's not something you would notice. It would be slightly easier for you to tell exactly how far things are from you- especially useful for parking a car or if you have to throw something. You would get sun in your eyes more easily, because you would notice it more.

It really feels like it's the same as if you put an earplug in one of your ears, then try to explain how your hearing is different now. You would hear things on the ear-plug side less. You would be able to pinpoint where a particular noise if coming from less easily. But overall, it wouldn't change the act of hearing for you. Just like having 2 normally sighted eyes wouldn't give you any different visual process.

I have always wondered the opposite...how is it with vision only in one eye. I close one eye sometimes and see and feel very unbalanced. I imagine one would get used to it and it would become a norm. I have macular degeneration now in the left so things aren't clear all the time. It's not optimal but it is my norm now and I work with it the best I can.

I am the opposite! I had a cataract in my right eye and my left eye is nearly perfect. I’ve always wondered what it is like to be able to see out of both eyes. I am not completely blind in my right eye but without correction it is pretty close.

Presumably someone's told you about moving your head sideways to get a better depth perception of things. It's just like that, only when your head isn't moving as well as when it is.

Hey! I was born sighted and started losing my vision in 2016. I’ve had 10 or 12? surgeries. After about 8 on the right, the last in Oct 2018, I’ve been Very Blind (tm) in that eye. There’s a lot of fluid behind the retina so there’s not even much light information.

Seeing with two eyes is like easy mode. I’m sure you’re more used to it having not had bilateral sight, but adjusting is a rough time. I rely a lot on proprioception instead of depth perception now because my brain is like “wooooooah!!” A lot.

I didn’t miss the curb or feel out stuff with my foot so much/at all. I startled much less easily with stereoscopic vision because people don’t assume your sight areas - you have similar to average peripheral vision.

I could watch a 3D movie, not get as carsick :p

I lost the ability to ride a bike and haven’t been able to tackle it yet.

I don’t feel comfortable driving anymore, partly because the bad eye sometimes reads bad light information that’s really off and distorted.

Also I miss the bottom step in my house a lot. That was less frequent with stereoscopic vision. It’s just less work to exist and move in the world comparatively.

I probably won't give a good answer, since my vision in both eyes is garbage, but recently my brain has started to stitch input from both together. This usually happens if I'm concentrating on it, or if I'm high. It's a bit like going from a full screen TV to a wide cinema. It's a little freaky. Keep in mind, it's a very blurry cinema; the projectionist hasn't focused the image and she's smeared the lens with vaseline, but it's still a big ol' wide cinema.

I’m always curious as well. I’m pretty much blind in my left eye and have been since I was 6, I can only see hand motions. My brain can’t comprehend how seeing with two eyes would even work lol

I’ve always had vision in both eyes (and do) but the thing is, do you see nothing in your left eye or just normally but just through your right eye?

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