Colour perception problems, short of total colour blindness: yet another symptom of PD?

I've always passed colour blindness tests, the last being approximately 7 years ago. But not now.

There's been a few cases in recent months where I've disagreed with family members about the colour of something: I'd say it was brown, they said green.

But I thought nothing of it until this morning. I was using resistors (electronic components) whose values are shown using a series of bands of varying colours: brown=1, red=2 etc.. I saw a pink band. The problem is that pink is not part of the code. Measuring the value of the resistor using a multimeter showed that I should have been seeing an orange band.

Next stop an on-line colour blindness test at:

http://www.colour-blindness.com/colo...r-test-plates/

Where I got a few tests wrong. They point out that taking the test on a computer does not give definitive results, because the monitor might not render colours perfectly.

There's not much in the academic literature directly linking colour perception issues and PD. But there is an interesting paper by a Tehran based group. (If my studies are anything to go by, a disproportionately high number of good "practical" PD papers come out of Iran.) In it, Tabassi et al. write [1]:

"we came to the conclusion that the color vision deficiency
in the tritan axis is a clinically significant dysfunction
in Parkinson disease patients, even to the extent to be
considered as one of the overt signs of the disease.
Yet, no clues to the anatomic location of this
dysfunction (retinal, cortical, or anywhere in the visual
pathway) can be inferred from these results."

Has anyone else here had a similar experience?

Reference:

[1] "ACQUIRED COLOR VISION DEFICIENCY IN PARKINSON'S DISEASE"
S.A. Tabassi, S.G. Sepanlou and J. Lotfi
Acta Medica Iranica, 41, 2003
http://journals.tums.ac.ir/upload_files/pdf/_/52.pdf

John

Some of the dyes used to color things are fugitive. They tend to change with exposure to light (fluorescent light especially or sunlight).

The color changes you describe are common with some colored pencils that are not lightfast. Yellows and reds(esp pinks) are the most affected. (they are often mixed into various "brown" shades.) Drawings/paintings done with non-lightfast pencils or paints (many art supplies coming out of China like Marie's brand for example) fade very quickly.

This may not be a factor for you, but it is worth considering that the environment may not be as stable as you think.