Updated June 10, 2015.

Definition: An involuntary eyelid muscle contraction, typically involving the lower eyelid, less often the upper eyelid. The condition occurs and disappears spontaneously, but can sometimes last up to three weeks.

Frequent contributing factors include too much caffeine, high levels of anxiety, fatigue, stress, overwork, and a lack of sleep. Usage of certain drugs and alcohol may also be involved.

Also Known As: Blepharospasm