depth perception -> dizzy

[Steve]

I've been struggling with dizziness for almost two years. I hope someone can
relate, share some experiences, and/or give advice. Here's my story:

I've seen about 20 doctors, had about as many tests (all normal, except ENG
showed a small deficit), and tried about 20 medicines. Nothing has produced
improvement. All along I've suspected a binocular vision problem, but it took
until a few months ago to find an optometrist with energy to pursue it.

My level of dizziness varies day-to-day, and ranges from incapacitating to
annoying. I'm pretty much dizzy all the time, but have learned that close
(within about 8 feet) visual effort makes the symptoms worse. Distant visual
effort (for example, watching TV at 10 feet away) doesn't bother me, in fact, it
makes me feel better. I sense that if I could avoid all close visual work for a
week, the dizziness would be gone temporarily. Reading, and computer work (like
typing this message!) bring on symptoms, the severity of which are exponentially
proportional to the duration of the visual effort.

I've been doing visual therapy for a few months now. Certain exercises have
triggered severe bouts of dizziness that put me in bed for days, and invoked
nausea that lasted over a month. The worst was called "rand dots", in which I
attempted to see a 3-D picture emerge out of a group of scattered small dots.
Next worst was called "lifesavers" in which I attemped to merge red/green
circles on a transparent card held at arms length. This one made me sick for
about 4 weeks. And, I only did the exercise for about 30 seconds.

Since close work has proven troublesome, the therapist now has me doing
exercises at a greater distance. Late last week, we tried a 3-D image exercise
that employs polarized lenses (sorry I don't know all the names/terminology).
Anyhow, I realized I could perceive depth in the image, provided my head was
absolutely still. If I moved slightly, either side-to-side or up-down, the
depth disappeared. When I stopped moving, the depth snapped back into view
within about a second. The therapist found this unusual, and I hope to discuss
it with the doctor this week.

It seems to me that if I'm losing depth perception while moving, that could
cause the dizziness. Is there a name for such a deficit?

For over 25 years I've known I had a difference in visual acuity between both
eyes: left eye is a bit farsighted, right a bit nearsighted. I believe I became
conditioned to this, and automatically supressed vision from one eye or the
other depending on the situation. For example, for driving I automatically used
the farsighted eye, for reading I used the nearsighted one.

Even so, I started getting headaches that were traced to visual work, and got a
pair of glasses for reading. The glasses virtually eliminated the headaches,
but a few weeks later the dizziness began. My theory is I had learned to use
one eye for reading, and now that I could suddenly see the text with both eyes
(thanks to the glasses) that confused my brain.

I've scanned the usenet messages from others with binocular vision problems, and
can report similar experiences. For example, as a kid I had a devil of a time
learning to catch a baseball in the mitt. When I first learned to drive, I
constantly felt like I was not staying in the lane, and it took me thousands of
miles to learn otherwise. I suspect that due to a binocular vision problem, my
brain had fewer depth perception clues to go by, and therefore it took longer
for me to learn these tasks.

I used to go to the batting cages every so often, and could hit a pitched
baseball fairly decently. With the dizziness, I found I'm lucky to touch 10% of
the pitches. It became too frustrating so I stopped.

But, of most concern now is my inability to do computer work, reading, or any
other close-up visual task without getting ill. The few minutes it has taken me
to enter this message will require hours of rest to recover back to my baseline
dizziness level.

So, I'm hoping to learn more about the connection between depth perception and
dizziness. Similar experiences, treatment ideas, etc., would be appreciated.
Thanks.

[gman]

"Steve" <inte...@NOSPAMinsystem.com> wrote in message
news:39FDE221...@NOSPAMinsystem.com...

> I've been doing visual therapy for a few months now. Certain exercises
have
> triggered severe bouts of dizziness that put me in bed for days, and
invoked
> nausea that lasted over a month. The worst was called "rand dots", in
which I
> attempted to see a 3-D picture emerge out of a group of scattered small
dots.
> Next worst was called "lifesavers" in which I attemped to merge red/green
> circles on a transparent card held at arms length. This one made me sick
for
> about 4 weeks. And, I only did the exercise for about 30 seconds.

I have tried doing this also. Merging red and blue made to be seen by
people with normal eyes. It doesn't work for me because one eye
converges differently to a radically different place. That's why i'm
writing
programs that are adjustable so that the user can ease into this with a new
setting. Starting with zero change (where the colors are offset to match
your natural deviation and stepping to normal convergence over time.

I'm all for 'switching on' the visual centers first before trying to
straighten
out the eye muscles.

You might know better than me whether the visual centers can
even be switched on ( IF you have normal convergence i.e no
crossing eye). If you have the crossing eye then you might
want to take it much slower. Don't play ANY computer games
and by all means keep your graphics scan rate above 60 hertz -
try 70 or 75 Hertz. 60Hz would make anyone dizzy or blind
in no time.

Hope to port some samples over to JAVA in the next few months
for people to try on the web. The program i'm most excited about
is to allow the 11% of the population who can not see StereoGrams,
have them compiled specifically for their eyes - to see the infamous
3D effect which they'll otherwise never see.

tom_