I have a few suggestions for people, having used computers from a very young age and having my own since 7th grade, eye strain has always been an issue.
(1) If you are near sighted (which I am), have your the prescription *slightlt* detuned, so it isn't perfect. Mine is detuned by I think around 0.25. This reduces eye strain by a HUGE amount. You won't be able to read highway signs from far away but who needs to do that any more with gps nav?
(2) Tinge your desktop foreground coloring scheme more towards the greens and do not yet a dead-black background solid, and do not have a bright background picture relative to your windows. This reduces excess contrast while simultaneously allowing you to reduce the brightness of the screen. Excess contrast is a major source of eye strain. If you see characters burning into your retina excessively you have too much contrast.
For example, for xterm's I use the following resources:
(3) Monitor(s) should be arms-length from your eyes with your fingers stretched out. If they are any closer, you are doing something wrong. Any closer and your eyes will get strain for excessive crossing.
(4) Glasses vs Contacts. I don't know. I prefer glasses myself, but I've never really liked to use contacts so mostly I just don't any more... its glasses all the way.