Since the popularity of computers began the meteoric rise, there have been questions associated with computer screens and eye strain. Some say the evidence is clear that they can damage a person's eyesight. After all, if they cause eye strain and discomfort, that is the body's way of saying something. However, the extent to which computer screens damage eyesight is somewhat unclear.
There is a great deal that is known. First, eye strain from prolonged computer use is a fact, though some people are more susceptible to it than others. Second, it can usually be prevented or relieved in a few easy steps. Third, technology, which is partially responsible for the problem, can also offer a partial solution.
There are plenty of symptoms that often show up as a result of eye strain from computer screens. It may first start with a little soreness. Then, it may progress to dry eyes, blurred vision and even headaches. Taking a ten to 15 minute break every hour is a good way to help avoid this and rest your eyes, though some employers may not be as generous with their break periods. If possible, break up computer tasks and non-computer tasks throughout the day as much as possible.
One of the major improvements in computer screens has also helped. LCD screens tend to cause a lot less eye strain than the traditional CRT computer screens. Still, even an LCD screen, if it is not properly calibrated or if it is too bright, can be just as hard on the eyes. This is very important as many people tend to keep their LCD screens too bright, simply because they are not viewing them from a proper angle and may be trying to compensate for the "screen door" effect.
Fortunately, most of the eye damage, if it is to be called that, resulting from the use of computer screens tends to be a short-term situation. Once the eyes are rested, the symptoms tend to quickly go away. However, if the eyes are not sufficiently rested, the symptoms may return quicker than they appeared at first once computer activity resumes.
While these short-term effects are well documented, the main question on people's minds is if computer screens are able to cause permanent damage over time. The data is not sufficient on this question one way or the other. While many who work in office environments and have worked with computers all their lives have developed eye problems, many others have not. Perhaps in the future, the research will be completed that can fully answer this question.

http://www.wisegeek.com/do-computer-screens-damage-your-eyesight.htm