Situating your monitor directly in front of a large window may create strong backlighting conditions which can result in squinting and eye strain. Conversely, computers with large windows directly behind the operator will also tend to have excessive natural glare across the screen. To alleviate both problems, place your screen parallel to windows to minimize glare. Most monitors come equipped with a pivotal base to allow for tilting up and down and swiveling from side to side. Find the best angle with the least glare.
Fluorescent lights tend to be very white and harsh on the eyes.
If your workstation has a bright light above it, place a cardboard hood over the monitor to provide shade across the screen surface. Be sure not to block the ventilation openings. Vary your activities throughout the day so that computer work is intermittent. Changing activities allows your eyes to rest, helping to reduce chronic strain. Altering activities also allows other muscle groups to relax and stretch.