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From: pipercub!fenwick@clipper.ingr.com (Steve Fenwick)
Newsgroups: sci.virtual-worlds
Subject: Re: VR hardware safety response
Message-ID: <1991Jun6.201248.3573@milton.u.washington.edu>
Date: 6 Jun 91 16:36:04 GMT
References: <1991Jun5.031158.15999@milton.u.washington.edu> <1991Jun5.224106.
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In article <1991Jun5.031158.15999@milton.u.washington.edu> kilian@poplar.
cray.com (Alan Kilian) writes:

>galt@hellgate.utah.edu (Greg Alt) Says:
>
>> It seems that CRT's are a possible health risk and should not be used 
>> right up against your eyes for a long time.
>That debate rages on and until I see some more articles I am not going
>to put any CRT based displays right in front of my eyes. The "Light valve"
>designs seem much safer in the mean time.

(I don't claim to be an eye expert, but I do listen to my opthamologist.)
There's a different risk, and much more important, and that's forcing one's
eyes to focus at a more-or-less fixed distance for extended (>20 minutes)
periods.  The eye apparently gets conditioned to this, and tends to
lose its ability to focus across a wide range of depths.  This is
not just a problem at very close (e.g., eyeset) distances, but
also for normal CRT users, heavy readers, etc.

Give your eyes a break; focus on something other than your CRT
at least every 20 minutes.

Steve Fenwick
-- 
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