You can customize the duration of your work time and length of breaks (in minutes). During the break time you may exercise your eyes - look away or look at distant objects, etc. You can also password protect the program from disabling the ‘break’- useful for protecting children who plays video games much too long time, forcing them to take breaks.
Previously I posted a topic on one such tool EyeDefender that can also consider here. Eyes Relax can be downloaded from here or here. The program is straightforward and very easy to use. Required Microsoft .NET Framework 2.0 for Windows XP. Supports Windows XP and Windows Vista