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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