Eyestrain is another problem that can be encountered in front of a computer. It can cause headaches, difficulty focusing, and increased sensitivity to light. To prevent eyestrain, ""The distance to the screen from your eyes should be about an arms length away. You should also be able to comfortably read what's on your screen at that distance, without having to squint.""
If you can't read your screen from an arm's length away, simply increase the font size on your computer.