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From: jsdy@hadron.UUCP (Joseph S. D. Yao)
Newsgroups: net.med
Subject: Re: Contact lenses
Message-ID: <182@hadron.UUCP>
Date: Sat, 11-Jan-86 16:31:36 EST
Article-I.D.: hadron.182
Posted: Sat Jan 11 16:31:36 1986
Date-Received: Tue, 14-Jan-86 03:49:09 EST
References: <640@wjvax.wjvax.UUCP>
Reply-To: jsdy@hadron.UUCP (Joseph S. D. Yao)
Organization: Hadron, Inc., Fairfax, VA
Lines: 18
Summary: Explanation of "osmosis"

I suspect (but don't know) that the need for saline over water
has something to do with osmosis.  The way osmosis works is that,
if there are neighbouring solutions with differing concentrations
of something, they will try to equalise by passing the solute to
the less concentrated side or the solvent to the more concentrated
side or both.  This may or may not be directly a problem with lenses
swelling.  However, once you put them on your eyes, this will cause
problems with your eye's fluids.  Distilled water in the lenses may
try to draw the salt solution in/on your eyes out.

I wouldn't have a problem washing and storing lenses in (sterile)
distilled water if there's need.  But I'd soak them in two changes
of saline for several hours each before putting them back in my
eyes.  (While this is hypothetical for me, as I wear glasses, I've
just gone through this whole discussion with a sister of mine.)
-- 

	Joe Yao		hadron!jsdy@seismo.{CSS.GOV,ARPA,UUCP}