Essential blepharospasm is a debilitating disorder of progressive involuntary spasms of the eyelid muscles. Other muscles of the face and neck may also be involved. Essential blepharospasm typically begins by the patient noticing an increase in blinking or squinting with a progression towards repetitive forceful closure and difficulty opening the eyelids. Blepharospasm is more common in women than men and typically has its onset in the fifth to sixth decade.

Most medications have limited efficacy in treating blepharospasm. However, treatment with botulinum toxin (BOTOX®) has proven to be a successful treatment for the disease, although not a cure. Treatments typically last for three months and need to be continued for ongoing relief.

Hemifacial spasm is a related disorder that usually involves involuntary spasms of the muscles on only one side of the face caused by abnormal stimulation to the facial nerve. It too, is successfully treated with BOTOX®.