Thank you Beth and Bobby for your explanations, they were both excellent.

My eyes seem to track reasonably well, at least no medical / PT / OT type people have
commented otherwise.  Tracking an object seems to be a fairly common test when someone
evaluates my neurological state.  I wear glasses to correct short sight, and both eyes are
excellent with the glasses on.  I do know that my left eye (left is my least affected side CP-wise)
is definitely dominant.  I struggle with binoculars, 3D Glasses and the like because I perceive
more from the left eye than the right.  If I cover my left eye my brain still tries to use it, which
feels really weird.

Given that it only really bothers me when I am triking, it is more of an inconvenience than a
problem.  I was just curious about what causes it.
Cheers,

Jeremy

On 30 Nov 01, at 9:45, Elizabeth H. Thiers wrote about Re: balance and growing up with CP:

> Bobby you are just too smart.  Figured if I waited to see if anyone
> answered first.  Now for the OT side of it.  Bobby's right there are five
> skeletal muscles that move the eye, side to side up and down, around etc.
> They are also highly innervated by cranial nerves (direct input into the
> brain)  One of the main things I look at for the kids I evaluate is simply
> vision test. Not the kind the eye doctor gives you, but can you track
> accross midline and do your eyes converge (come together) and diverge (go
> apart) smoothly. These functions are controlled by those skeletal muscles
> connected to your eye ball.  Depth perception is the result of your two
> eyes working together near pt. convergence and far point.  Each eye sees a
> different picture and when put together in the brain gives you a
> stereoscoptic (sp?) view of the world (think 3-D glasses or those
> Victorian stereoscopes with two pictures, or view finders) If along the
> way your eyes aren't lining up properly the brain takes over and often
> times cuts out information from one of the eyes, thus no binocular vision,
> no stereoscoptic view, etc.  That's one way. So think about how folks with
> CP and other neurological disorders have difficulty voluntarily
> controlling muscle movements and how depth perception is a quick change
> muscle movement as your eyes adapt to a changing environment and it will
> make sense. That's my 2 cent lecture on vision.  It's very fascinating
> stuff.
>
> Beth the OT
>

---------------------------------------------
Jeremy Persen, Programmer, Vista Software Ltd.
Nelson, New Zealand
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