From: gad@eclipse.its.rpi.edu (Garance A. Drosehn)
Subject: Re: Progressive nearsightness from CRT use
Date: Thu, 10 Sep 1992 05:24:51 GMT

Comments on the topic being discussed:

My eyes started to go nearsighted when I was in my early teens.   
Coincidentally, I'm sure, this is about the time that I started reading a  
lot of books.  By the time I got to college age, they had developed to the  
point that one of the eyes couldn't be corrected to 20/20 with glasses.

In college I got into computers.  Over the past 15 years, the majority of my  
waking hours have been spent staring at one computer screen or another.   
Over that time, my eye perscription has not changed enough to notice (it has  
changed a little bit, but my eye doctor tells me it's not enough to get new  
glasses for unless I wanted to buy new glasses anyway).  I can still wear  
glasses that I bought 10 years ago -- in fact I am right now, because I  
broke the most recent pair of glasses that I've bought.

Notes:

While I loved contacts, they were disasterous for me.  After a day of  
wearing contacts at work, my long-range vision would be pretty bad.  Wearing  
contacts on a day where I wasn't doing close work did not cause any trouble,  
so it wasn't the contacts themselves so much as wearing contacts while doing  
long stretches of close work.

Since then, my own habit is that I take off my glasses when working at a  
computer.  I believe this helps my eyes a lot.

The strain on the eyes depends a lot on the screen you are using.  The  
"VT100-style" screens (with the really light-blue on a black background)  
caused me troubles.  Most IBM 3270 models were Okay for me.  I liked the  
3180 in particular.  There was a color 3270 (3179? I forget now) which was  
*murder* on my eyes.  I had to have it replaced within a week of getting it  
(all devices of the same model caused the same strain).

There are times when eye strain can be caused by interference (of sorts)  
between the refresh rate of the screen you are looking at and any florescent  
(sp?) lights in the room.  I have noticed this on Mac screens, at times.   
Once I notice the flickering of the screen, I pretty much have to go home  
because I won't be able to ignore it.  "Interference" is probably the wrong  
word there, but in any case I sometimes notice that my eyes feel much more  
comfortable if the florescent lights in my office are left off.  I do not  
notice this problem at home (where I have incandescent lights).

It's a good idea to look away from the screen every once in awhile, to give  
your eyes a chance to focus on something far away.  I read that somewhere  
along the line, and it does seem to help.

All the above are my own "feelings".  The only concrete statement that I can  
make is that my perscription has not changed much over 15 years of staring  
at computer screens, and that includes many days where I have spent 16 or  
more hours in front of a computer.  It may be significant that my eyes were  
already nearsighted before I ever played with a computer.

It would be nice to have more factual information to base these feelings on.

I am also probably fortunate to have worked in a place where I could always  
trade off any screen which bothered my eyes.  We have a mixture of machines  
here, and I've always managed to fine someone who would take a terminal (or  
workstation) that bothered me in exchange for something which worked better.   
Apparently the screens that bothered my eyes did not bother theirs.

--
Garance Alistair Drosehn     =     gad@eclipse.its.rpi.edu
ITS Systems Programmer            (handles NeXT-type mail)
Rensselaer Polytechnic Institute;           Troy NY    USA