Xref: utzoo sci.med:25702 sci.bio:5179
Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!tdatirv!sarima
From: sarima@tdatirv.UUCP (Stanley Friesen)
Newsgroups: sci.med,sci.bio
Subject: Re: Color Blindness
Message-ID: <40@tdatirv.UUCP>
Date: 14 Jun 91 18:30:38 GMT
References: <0B02FFF5.htcdri@harvs.UUCP>
Reply-To: sarima@tdatirv.UUCP (Stanley Friesen)
Followup-To: sci.med
Organization: Teradata Corp., Irvine
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In article <0B02FFF5.htcdri@harvs.UUCP> romed!harvs!harv@asuvax.eas.asu.edu writes:
>I am looking for information about color blindness.  I am slightly red-green
>color blind, meaning that I can confuse certain shades of red and green.
>
>I assume that the problem is that my eyes cannot differentiate between
>frequencies as accurately as they should be able to, because if I see certain
>colors reflected off glass (not a mirror - a crude reflector, like a car window
>at night) the colors are more distinct.

Good enough as far as it goes.  The eye has three types of color sensitive
receptors (conventionally called Red, Green and Blue - but that is an
oversimplification).  These are wired into the optic nerve in an arcane
way that recodes the light levels into two color opposition systems.
These two are a Red-Green opposition and a Yellow-Blue opposition.  Red-
green color blindness is caused by some defect in the Red-Green opposition
system.  That is the R-G encoding has reduced contrast - or even no
contrast at all (in severe cases).  [There is also a third opposition -
between light and dark].

This can be caused by several things - one of the receptor types could
be missing, leading to reduced signal differentiation; or the peak
sensitivities of the red and green receptors could be offset towards
each other; or ...

As to why reflection helps, I do not know.

>Does vision acuity affect color vision?  Say, if I have 20/40 vision, will
>my color vision be better if I wear glasses to correct it to 20/20 or 20/15?
>(I do not wear glasses - have about 20/25 or something).

I doubt it, but I do not know for certain.

>Are there drugs which affect color vision?  Do certain vitamins or minerals
>affect the way eyes interpret colors? (other than hallucinogens)

Quite likely, and probably.
Anything that alters the metabolism of the receptors or neurons could
alter color vision under the right conditions.
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uunet!tdatirv!sarima				(Stanley Friesen)