A real concern about sitting in front of a monitor is eyestrain. When you work in front of a monitor, you tend to blink less frequently, which can make your eyes irritated and sore.
There are several things you can do to help reduce the irritation. Taking breaks and looking away from the screen will help. Also, using rewetting drops or artificial tears when you feel your eyes getting dry will go a long way in decreasing your eye irritation. Also, you may ask your eyecare professional about computer glasses. These may help your eyes when using computers for long periods of time.