This is a fancy way of saying pain or sensitivity to light. When an eye is irritated, the iris muscle inside the eye becomes sensitive. The iris is the colored part of our eye – it is a round muscle that dilates and constricts the pupil to control the amount of light entering the eye. This muscle can become inflamed and hurts. With bright lights, the muscle “spasms” and hurts even more. Photophobia can be treated by dilating the eye with cycloplegic eye drops. These drops dilate the pupil, but they also temporarily “paralyze” the iris muscle so it won’t spasm. It is like “paralyzing” a broken leg – by immobilizing it in a cast, you don’t walk on it, and thus it won’t hurt as much. If you are experiencing new photophobia, you should see your eye doctor to insure you don’t have a corneal abrasion or more serious internal ocular inflammation such as uveitis.