Symptoms of blepharospasm commonly appear after age 50. Initially, patients may complain of eye irritation or excessive blinking. Over time, symptoms become more frequent and the eyelids may stay closed for longer periods of time. In severe cases, the eyelids remain closed for several hours at a time, leaving the patient functionally blind. The exact cause of blepharospasm isn't known.
Risk seems to be increased in patients with a history of head trauma and loss of consciousness.
In some cases, it runs in the family. Certain drugs can cause the symptoms, but reducing the dose usually makes the problem go away. The drug is a toxin produced from the bacteria, Clostridium botulinum. Minute doses are injected into the muscles in several places above and below the eyes. Once inside, the toxin blocks the release of chemicals needed to transmit nerve impulses in the muscle, weakening the muscle.