Why Doesn't the Brain Compensate for Astigmatism

sinsanity2006

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I've heard that the brain compensates for many things. Why doesn't it compensate for astigmatism?
 
Interesting question. I've heard there were experiments done in which test subjects were fitted with goggles which had lenses which made them see everything upside-down and backwards. Eventually, their brains compensated for it, and they no functioned normally. Then, when the goggles were taken off, there was a similar period of adjustment back to normal.
 
I have a severe astigmatism, and my brain compensates by using primarily my left eye solo. It takes effort and results in some discomfort to use both.
 
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Like with everything else there are limits. Your body will do the best it can to remain functional, but as the extent of damage/malformation increases, the less functional it is. More or less a truism.
 
You might as well ask why your brain doesn't compensate for near sightedness. It is a focus problem, not just a distortion problem.

I've got astigmatism (to some degree) in both eyes, as well as being near sighted. If astigamatism were just distortion, then I'd see shapes differently with and without my glasses. Since I see shapes the same (allowing for fuzziness) with and without my glasses, it seems the distortion doesn't count for much.

When the eye doc is checking my eyes for a new prescription, the biggest difference the astigmatism changes make is that things get sharper when he adjusts the cylinder lens settings. There is some visible distortion as it is rotated to find the correct angle, but it is really only noticeable during the rotation. When the lens is stationary, the distortion is not noticeable.
 
The form of astigmatism I have means that without my glasses things appear blurred out horizontally. I assume this is to do with the compromise between the axes that my brain has arrived at. Effectively, my eyes are short-sighted on the horizontal axis but more or less normal on the vertical axis, so that, for example, while I can see exactly where the top and bottom of a line of print are, the verticals in the individual letters tend to be too blurred for me to be able to make them out. Without specs, I also have trouble guaging distances because I cannot focus on verticals properly. Because the eye forms an out-of focus image, the infomation is not there for the brain to use.
 
Is this why, when I take off my glasses and look at people, I can see only a vertical shape, too narrow for a human? It looks like when you're under two bright lights at night and the shadows cast overlap, the area of overlap is darker. That's what people look like without my glasses.
 
sinsanity2006 said:
I've heard that the brain compensates for many things. Why doesn't it compensate for astigmatism?
Click to expand...

That's a great question. We've been able to create computer programs to compensate for blurry photos for years. Like others have said, I guess we're bumping against a hard limit of the human brain. Sucks to be mortal and finite.
 
It will compensate to a certain extent.

I have astigmatism in both eyes. Where I see things is not where they really are, so for example I can't play tennis...... it looks like there must be a hole in my racket, because I get awfully close but can not hit the ball. On the other hand, I'm an artist by profession and have trained myself so that I know where to put lines to make things come out right, when dealing with a piece of paper in front of me. I am so accustomed to compensating that I refuse to have this corrected by glasses - I think it would take me a long time to train my eyes again. I can't even tell that I am compensating. It is simply the way I see when viewing things close up. I automatically draw them correctly without even trying.

With the tennis racket thing, I could, if I spent the time, train myself to perceive where the ball actually is in space, and then I would be able to hit it. Since I have no interest whatsoever in tennis, it does not seem worth the effort it would entail.
 
The answer is basically that the "enhance" computer ability in sci-fi movies to make fuzzy pictures crystal clear so you can see what that license plate code is doesn't actually exist, nor CAN it exist, because that information is not in the existing image to "enhance" out of it. The brain can't just "enhance" the image with information it doesn't have. Well, it can to an extent, like what it "expects" to see there and other optical illusions, but these are illusions and if the brain did that far more than it does as it stands, our sight would be rendered pretty much useless by a bunch of made-up stuff.
 
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