Our retina is responsible for our perception of color vision. Although we still have only a theory of color vision, we have a pretty good idea of how it works. It is mediated by the cones of the retina and when they are exposed to a particular color for an extended period of time, they become ‘bleached’, or desensitized to that color. Since those cones are temporarily non-functional, the other neighboring cones become more effective and they produce a color which is complementary, or opposite to the original bleaching color.

This condition is called the McCullough Effect. For example, looking at the color green for a long time will exhibit a red (or pinkish) after-image while looking at a white surface. This has been demonstrated in almost 20% of computer users but there was no permanent effect. Working on a full color monitor with various colors used throughout a day will likely not create this condition. Also, taking frequent breaks will help to alleviate this condition.