I'm using a CRT monitor right now (my LCD screen is broken), and it's currently set to 1024 x 768 at 85 hz, according to the OSD. Can a monitor with a refresh rate like that cause eye damage or eye strain? What is the optimal refresh rate for CRT monitors, and how might I go about changing the refresh rate if it's too high? In the past I have gotten headaches from monitors when the refresh rates change, so I wanted to ask about it.
85 should be fine. At 60 ish you'll likely notice flicker which can cause some eye strain issues, but you should be ok with 85.
Higher is better by the way, and 85 was a typical refresh rate for a crt monitor back when they were popular.
Also note that LCD monitors often state having a refresh rate of 59/60 Hz, but it's not the same thing in terms of eye strain. Because the pixels on an LCD don't turn off between updates, you don't get refresh-induced flicker on an LCD, hence 60 on an lcd is normal, and totally fine.
I'm not going to re-phrase the answer above just for the sake of it, pretty spot on, a colleague of mine a while ago showed me a good way of checking if the rate is set right for you.
if you face your monitor and turn your head so that you can only see the monitor out of the corner of your eye, you will either see flickering or you wont, if you do you need to change your settings/monitor.. I dont know the science behind this but before the days of LCD this was great.