[techmind (OP)]

Hi,

I've been suffering from a flu-like virus thing the past few days. I've long observed that when I am ill and have a raised body-temperature, my colour-perception is subtly affected and my room or environment seems more yellowy-greeny than usual.

Do other people experience the same thing?
Is the colour-shift in the same direction for everyone?

Is it documented in the medical literature?

What's the physical origin?
Is it that the three colour-sensors in the eye have a differential change of 'gain' (or sensitivity) with temperature?

[RD]

Medications can change colour vision, e.g. ...

Ibuprofen Side Effects ... changes in color vision

http://www.drugs.com/sfx/ibuprofen-side-effects.html

Cyanopsia [blue tinted vision] also sometimes occurs as a side-effect of taking sildenafil (Viagra)

http://en.wikipedia.org/wiki/Cyanopsia

Digoxin overdose - can cause yellow or green colored vision.

http://www.wrongdiagnosis.com/c/color_blindness/underly.htm#underly_list

[techmind (OP)]

Thanks for the links, but I'm not taking any of those medications - and I've noticed this slight colour-change before taking any medication. The slight yellowy-greenness does come and go seemingly correlating with my temperature going up and down.

I should clarify that my perceived colour change is fairly subtle, but (probably through self-training and interest in photography and colour vision) I may have a more literal sense of colour (and colour-temperature) than many people. Outdoors, given the wide natural variation of lighting, I may not notice, but indoors with tungsten illumination (always same real colour) the effect seems quite unambiguous.

[RD]

The only non-medication cause that immediately comes to mind is optic neuritis, however that is usually painful, and the colour change would typically not be the same in both eyes ...

Many patients with optic neuritis may lose some of their color vision in the affected eye, with colors appearing subtly washed out compared to the other eye.

http://en.wikipedia.org/wiki/Optic_neuritis

Optic neuritis is inflammation of the optic nerve, which causes loss of vision usually due to the swelling and destruction of the myelin sheath covering the optic nerve. Some causes are viral-bacterial infections

http://en.wikipedia.org/wiki/Optic_neuropathy

[Pwee]

There are some other things that came to my mind:
I remembered hearing somewhere that there were attempts in the military to alter human vision (hopefully to be sensitive to the infrared spectrum) by manipulating diet (specifically vitamin A intake). I googled it and here is a page that gives some details:
http://www.edkeyes.org/blog/050825.html
So your sickness may cause your vitamin balance to be off and it may affect your color vision subtly through vitamine A ()

The other thing is slightly more off, but since now-days I'm reading a great deal of research in this field, I'll mention it:
There are some people who report seeing colors caused by a variety of stimuli. They have a condition called Synesthesia. Synesthesia have many forms, sometimes illusory color vision pairs with sounds, like if they hear a musical note A, they perceive a red color, for a note C they see green color, but there is no color at all.
This illusory color can be paired to all kind of things, like seeing letters, or words, it can be paired with olfactory stimuli too.
So maybe (it's really a wild guess) in your case it's paired with the perception of the body temperature or some other inner bodily stimulus.
The condition is harmless, it has to do with some extra wiring in the brain that connects a part of the cortex responsible for a part or modality of perception with the part responsible for color vision. Also I don't know of any case reported of someone who has inner bodily percept - synesthesia (in fact inner bodily perception is mostly not even done by the neocortex.