My eyes are similar, but even more extreme (20/25 and 20/180) and I also have very little depth perception in most circumstances.
I can also see the latest batch of 3D movies reasonably well. However, comparing my description with other people’s, it sounds like I’m mostly seeing 3-D on the moving objects. When watching Avatar, I didn’t usually have a sense that the foreground plants were closer to me than the background plants, but I did perceive that the foreground characters were closer than the background.
Since the motion of the character already makes it obvious that they’re in the foreground, I think my brain took the rest of the 3D cues and ran with it. But with the stationary foreground items, it didn’t know what to do and kept them relatively flat. That’s the way it seems from inside my head, anyway.
I think the alternating images is the reason for the OP’s experience. When the “good” eye is blanked out, it doesn’t suppress the “bad” eye. I’m guessing that the images persist in the eye/brain long enough to enable 3D perception.
That sounds like excellent reasoning. However I’ve always been told that the maximum number of “frames per second” the eye can process is roughly 30 or so. If both eyes are being presented with information far quicker than 30 times per second, why would input from the impaired eye suddenly be treated as valid?
Just for the record, I do believe it was the RealD technology that the movie was presented in.
“Frames per second” is not really applicable to the way the eyes work. They are not transmitting a series of unanalyzed “frames” to the brain. Your “30 per second” may have something to do with the refractory periods of receptor cells (I am not sure if that is a reasonable figure or not - for nerve cells the refractory period is only a couple of milliseconds, I think), but that has nothing to do with a frame rate. Apart from anything else, there are lots of receptors and fibers there, all working in parallel, asynchronously, so even if one is in its refractory period, the one next to it probably will not be.
I don’t know whether rowrrbazzle’s explanation is plausible, though. 144 times per second does seem awfully fast for the brain to switch its way of doing things. It would be interesting to know what you experience in 3D movies that use two projectors (or 3D picture viewing systems, most of which do present different pictures continuously to each eye).
I’m basing the “frames per second” based on my limited experience with digital video and computer games. The NTSC film standard is either 24 or 30 frames per second to achieve the illusion of motion. In other words, 24 or 30 film or video frames must be displayed on the screen per second to create a convincing illusion of fluid motion. A series of frames displayed more slowly will look jerky. Thus I concluded that the optic nerve can only perceive or process ~30 fps.
Well, that is a faulty inference. The eyes, of course, are adapted to seeing reality, which does not have a frame rate at all, and neither do they. They are not movie (or video) cameras (and their job not to transmit a picture, or a series of pictures, back to the brain). They can see the discontinuity in movies with a frame rate that is too slow, but it does not follow that their frame rate is faster, or indeed, that they even have one.
The polarized 3D switches from one eye to the other 144 times a second, this is far quicker than the 24 times a second which is the minimum the eyes need to see one image instead of two. So the stereopsis function of the brain works.
In the real world, both eyes see at the same time, not alternately. So the amblyopic eye image is suppressed and not used by the brain. Alternating the image avoids the suppression and so 3D vision is achieved. This will only work with mild amblyopia like the 20/100 the original poster had.
In fact, anyone who plays a lot of videogames has probably already seen this in action. An action game running at 30fps looks a LOT less fluid than a game running at 60fps, which is considered to be the bare minimum for playability for first person shooters these days. You can even see the difference going up to 100fps or higher.
I don’t have amblyopia, but because of some other vision problems in the real world I have marginal stereoscopic vision at best. This has not really impaired me in life, although the FAA did ask me to undergo some rather thorough eye testing prior to granting my pilot’s license. As others have noted, the eyes and brain make use of several types of cues to judge distance.
I, too, have found that some of the modern 3D viewing technologies do, in fact, give me better stereoscopic depth perception than I get in real life. Why? I don’t know. RealD is definitely one of them. My spouse has done some extensive research into 3D TV’s and has actually located a couple systems that also work with my atypical vision.
It is a little weird that a movie gives me different/more depth perception than real life. I also realize this is counter-intuitive for those who watch with those same systems and see something less 3D than what they’re used to, but you’ll just have to take my word for it. It gets to be like arguing over color-blindness.
For the record, 1950’s era 3D with the different colored lens do not work for me - I usually see a doubled image, one red, one blue. My mind won’t combine them. I also can’t see anything in a “magic eye” picture, either, and suspect I never will.
Looks like I probably can do OK with modern 3D movies.
Point of information that I don’t see here:
If your eyes are grossly different, like mine (20/40 and 20/400 - the 20/400 one is great for reading small print, BTW - it’s like having a built-in magnifying glass - the eye is perfect except for being extremely nearsighted), when they are corrected with glasses the images are grossly different sizes. Understandable, if you think about it - one lens is thin and one is like a Coke bottle.
I realized in my 30’s that’s why I never could fuse, in spite of all the money my parents spent on my eyes (doctor visits, patches, gear, etc.) when I was little. At least my ophthalmologist wouldn’t let my eyes be cut on, thank goodness.
I was able to get some stereo vision with contacts (not so much difference in the image sizes), but I decided it just wasn’t worth the trouble and gave up the contacts and the exercises. I like my eyes just fine the way they are. Although it was a nice side effect that the exercises corrected (mostly) the crossing of the eye I’m not currently using, and seems to have made my nearsighted eye my dominant eye for distance as well as reading, although of course I don’t consciously see its image at distance.
I’ve often wondered how many other people have eyes as grossly different as mine.
I have nearsighted but correctable vision in my right eye and via a childhood accident at 4 years old I am missing the interior lens in my left eye (cosmetically it looks normal) so I have virtually no clarity of vision in that eye.
The optometrist was incorrect about 3-D vision. As others have pointed out in this thread a monocular person can have a surprising degree of effective depth in their filed of view vision and can catch a ball, drive etc.
There are limitations to this however. In parking I am always super conservative as I cannot tell visually looking over the hood whether I am 1 foot away or 2-3 feet away from an adjacent cars bumper that I cannot see. If I had full 3-D this would not be an issue.
Thing is, stereoscopic vision is the only way 3D works in movies. There is no parallax when you move your head or eyes. In fact, that is probably the reason even the best 3D movies look flatter than reality to many people.
Apparently (as I learned recently from the source), pilots don’t need to have depth perception. My niece is an airline pilot and has that condition. :eek:
She may not have binocular depth perception, but that does not mean she does not have depth perception at all. She surely does. As, johnpost pointed out, in the very post you quote, even people with one eye have depth perception, although not, obviously, binocular depth perception.
There are several mechanisms of depth perception that, in normally sighted people, work co-operatively. Only one of them depends on having two eyes, and (in real life as opposed to viewing of 3D movies) it is important only for seeing the relative distances or relatively close objects. Threading a needle without two good eyes is very difficult. By contrast, for tasks like driving or flying a plane, where we are dealing with objects that are quite far away, it really does not matter if you are one eyed or otherwise impaired in your binocular depth perception system. Distance judgment in those cases depends mainly on motion parallax (and perhaps texture gradients). Having two eyes rather than one will not help you very much.
I should have added re how current 3D movies look to me that I took my kid to see Avatar 3D version with the glasses when it premiered. It looked OK but kind of dim and I did not see any of the visual “pop” aspect of the 3D effect (when the flowers opened for example).