Re: [ATM] Retinal sensory cells

[Mark Holm <mdholm@telerama.com>]

Russell Jocoy wrote:
>   Mark ,   What a very informative listing on "night vision".   You stated 
> that cells in the retina replentish light information quicker in low light 
> levels.
Did you see the post from Nils Olof Carlin correcting me a little?  He
said the light sensitive chemical level does not change much but that
the build up of chemical that has been changed by exposure to light is
actually the thing that reduces low light sensitivity.

Nils Olof references this paper
http://web.telia.com/~u41105032/adapt/adaptation.htm

 Can we take supplements to help increase this replentishment?  I am
> serious and not making fun, Carrotine has always been an eye vitamin...
>     Has there been any scientific experimentation on increasing retinal 
> reception by supplements or
> other drugs? I am sure the government has plenty of data...

The sources I have read have indicated that no particular supplement to
improve night vision has been found.  Some things that definitely are
known to harm night vision are well established.  Tobacco smoking is
bad, though I don't remember in detail why.  Alcohol is bad.  Low blood
oxygen level is bad.  If you are up high, supplemental oxygen is
necessary to have good night vision.  Some medicines are known to be
bad, though I don't remember which ones.  General good health and good
nutrition are helpful.  Diseases that harm the retina, such as high
blood pressure and diabetes are obviously bad.  Certainly a serious
deficiency of vitamin A (beta-carotine) would be bad, but once you get
as much as your body uses, more just turns you orange.  (Evidently
severe overconsumption has actually been documented to produce orange
skin and to be somewhat toxic as well.)

Here is an approachable presentation of the physiology of vision written
by a neuropsychologist:  http://www.yorku.ca/eye/index1.htm

Mark Holm
mdholm@telerama.com

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