On Fri, 02 May 2008 23:42:53 +0200, andrel wrote:

>> Oh, we both have found it very fascinating - her ophthalmologist took
>> pictures of her eyes - most people you get a bright center (from the
>> reflection off the retina), but for those with this condition, it's not
>> uncommon for the iris to "leak" light and for the photo to show a
>> "spoke" pattern outside the pupil area.
> I think that also the white of the eye may transmit more. [..]

Possibly.

>> Well, the thing is, even when using just one eye, if your brain has had
>> practice at determining how far away stuff is, even with one eye you
>> adjust and still have depth perception.  I asked my wife about this (my
>> dad also had vision problems and I never understood the lack of depth
>> perception) - she explained it as a calculation problem - she can tell
>> how large something is compared to the surroundings, and if it's
>> something she knows how large it is relative to, say, her hand, that
>> helps -
> I'd imagine that all normal depth cues (you know, the ones we use when
> composing a good POV scene) should be available to her, some less
> because of the other visual problems.

Oh, probably, relative size of an object to environment, shadows and such 
are all a factor in determining position; but as I said (below), 
processing that data properly is an issue.  This is why she'd never been 
good at team sports - it's hard to catch a softball if you can't tell 
where it is until after it's hit you in the head.

>> but her brain doesn't have enough practice at calculating the distance
>> of an object moving based on those two reference points, and as a
>> result, she has very poor eye-hand coordination when it comes to
>> catching something thrown in her direction, because in order to figure
>> out how far away something is, she actually has to think about it,
>> while those who don't have the problem don't have to think about it. 
>> According to her doctor, it comes back to things not being hooked up
>> correctly between the optics and the brain.
> 
> Makes sense. With the two images far away in disjoint parts of the
> visual cortex it would be hard to combine the information. Hmm, I wonder
> if the condition is more severe in man. IIRC the two halves of the brain
> do communicate more in women.

From the wikipedia article on OA, there are variants that affect men that 
don't affect women.  

Jim

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