will johnston wrote:
>
> The effects of PD and Sinemet on vision seems to vary widely from person to
> person.  I have made several unusual observations in my case.
>
> 1. After taking a Sinemet tablet, my vision worsens temporarily. My ability
> to read where there is less contrast between the print and the background
> and/or where the print is relatively small decreases. I had suspected a
> focus problem in which my pupil diameter widened thereby admitting more
> light but decreasing my depth of field. I checked this by videotaping my
> eyes from when a Sinemet 25/100 [not CR] was taken until I was fully "on".
> (I placed  a reference marker strip [paper with 64 lines per inch grid]
> just above each eye before the test. I read aloud from a page with lines of
> random generated letters in decreasing point sizes. I continued reading
> each line aloud using a forced decision two characters
> beyond where I felt that I was merely guessing. After the Sinemet had me
> "on" I viewed the tape. My reading ability became increasingly worse after
> taking Sinemet, but, after a few minutes [six to ten minutes] improved,
> going back to the pre-medication level and better. Forced decisions did not
> produce
> any surprises and confirmed that I was just guessing beyond where I was no
> longer aware of being able to read. Frame by frame viewing of the tape and
> counting pixels on a large screen TV revealed no
> pupil diameter change.
>
> 2. A somewhat similar change occurs with a rapid change in atmospheric
> pressure. My vision becomes worse with a rapid increase in atmospheric
> pressure and improves with a rapid decrease in atmospheric pressure. I took
> a "ride" a year ago in an altitude chamber. I had taken no PD medication
> for more than 12 hours. I took a borrowed contrast sensitivity eye chart [a
> ridiculously expensive chart with letters of uniform size which decrease is
> print density from extreme black through grays to what I see as pure
> white]-with me. As I went rapidly to a simulated 3500 feet I was able to
> see two more letters than I had ever seen before. The extra two letters
> disappeared  almost immediately after stopping the climbing simulation.  My
> dexterity and smelling ability change with the change in pressure also.
>
> Any explanation?

I don't have one, but your careful experiments certainly should interest
other researchers who are trying to learn more about the nature of PD.
If you should consider publishing in a scholarly journal, a "letter to
editor" is the least demanding format. I think the first thing they
would look for is a repeat of the experiments on a similar subject who
doesn't have PD, for comparison. Cheers,
Joe
--
J. R. Bruman   (818) 789-3694
3527 Cody Road
Sherman Oaks, CA 91403-5013