Definition
Benign essential blepharospasm (BEB) is a progressive neurological disorder characterized by involuntary muscle contractions and spasms of the eyelid muscles. It is a form of dystonia, a movement disorder in which muscle contractions cause sustained eyelid closure, twitching or repetitive movements. BEB begins gradually with increased frequency of eye blinking often associated with eye irritation. Other symptoms may include increasing difficulty in keeping the eyes open, and light sensitivity. Generally, the spasms occur during the day, disappear in sleep, and reappear after waking.
As the condition progresses, the spasms may intensify, forcing the eyelids to remain closed for long periods of time, and thereby causing substantial visual disturbance or functional blindness. It is important to note that the blindness is caused solely by the uncontrollable closing of the eyelids and not by a dysfunction of the eyes. BEB occurs in both men and women, although it is especially common in middle-aged and elderly women.
With botulinum toxin treatment most individuals with BEB have substantial relief of symptoms. Although some may experience side effects such as drooping eyelids, blurred or double vision, and eye dryness, these side effects are usually only temporary. The condition may worsen or expand to surrounding muscles; remain the same for many years; and, in rare cases, improve spontaneously.
In most cases of BEB the treatment of choice is botulinum toxin injections which relax the muscles and stop the spasms. Other treatment options include medications (drug therapy) or surgery–either local surgery of the eye muscles or deep brain stimulation surgery.
Source: https://www.ninds.nih.gov/
