Flashing Lights Flashing lights are the sensation of lights being flipped on and off, particularly on one side of the eye. It continues even when the eyelids are closed and tend to occur in only one eye at a time. When the vitreous that fills the inside of the eye, pulls or rubs on the retina it can cause the appearance of flashing lights or lightning streaks. The same sensation occurs sometimes when one is hit in the eye. This condition occurs more often as people grow older and usually is not cause for alarm. However, an examination by an ophthalmologist is necessary to determine whether a retinal tear or retinal detachment has occurred, especially if all or part of the vision decreases. Treatment If you have experienced sudden flashing lights, contact your ophthalmologist immediately. Retinal tears or detachments are a serious problem that must be repaired surgically.  Back