On Fri, 02 May 2008 21:10:47 +0200, andrel wrote:

>> (She's got ocular albinism, which means the rods and cones aren't fully
>> developed, she lacks pigment in her iris, and the wiring to her brain
>> is different than everyone else's -
> 
> I always found it fascinating how two seemingly unrelated things as how
> the eyes connect to the left and right brain and pigmentation defects go
> hand in hand. But that is as a scientist with an interest in
> development. For the person involved it is probably slightly less
> fascinating.

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.

>> what this means is that she has very
>> poor depth perception and the combination of the wiring problem and the
>> lack of pigment in her iris results in high contrast changes (usually
>> dark->light) will literally blind her for anywhere from 10 seconds to 2
>> minutes.
> 
> I think that is mainly the lack of pigment, that makes light enter the
> eye via other paths than the lens and not being able to regulate the
> amount of light. So she has to rely on slower chemical processes to
> adjust the rods and cones to the level of light.

That could well be the case.

>> Which makes driving at night a real pa in the ass for her.
> 
> So, just like me, you are the one that drives home after parties?

Pretty much, yeah.  She very occasionally will drive at night to pick our 
son up, but never on the freeway or unfamiliar roads.

>> Not to mention the nystagmus
> Wikitime

Rapid eye movement - a kind of spasm.  Essentially what it means is that 
her eyes "jump" randomly, which normally makes it difficult to read 
anything for an extended period of time.  I don't know for sure, but it's 
probably not uncommon for people who have nystagmus to be slower readers 
as a result.  My wife doesn't have that issue - she's managed to train 
herself to keep up - I don't think I've ever seen anyone read books as 
quickly as she does, and she definitely is taking in what she's reading.

>> - though for many this is a problem, my wife actually has managed to
>> harness this somehow and as a result reads very fast.  But she wonders
>> how other people actually see words on the page because she knows she's
>> not reading the text linearly.
> 
> Less serious a problem, but I always wondered how the world would look
> if it was out of focus. Whatever trick I used I was never able to not
> focus. Well, time solved this one. Now to find out how the world looks
> if you have a dominant eye. Possibly like walking with one eye closed,
> but I guess it may be subtly different.

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 - 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.

Jim

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