Contact lenses aside, a possible cause of a change in eye color, especially in older people, can be malignant melanoma, a dangerous cancer. According to "The Mayo Clinic Family Health Book," melanoma can arise in the eye or spread there from elsewhere in the body. Usually only one eye is affected. If a brown spot shows up on the iris or white of the eye or if the iris of one eye changes to a different color from that of the other iris, an eye doctor should be consulted right away.

- C. Claiborne Ray