Blepharospasm is a kind of focal dystonia, meaning an involuntary tightening of muscles. In blepharospasm, those muscles are around the eyes, causing the eyelids to unintentionally shut. People with blepharospasm may also have photophobia, meaning an aversion to strong light, as well as a feeling of eye dryness. The disorder is often called benign essential blepharospasm, but this term has received criticism as blepharospam, while not life threatening, may be embarassing and impair one's life too much to be called benign, and it is hardly "essential."
Blepharospasm is relatively rare, and is not well understood. There is a theory that, like other dystonias, blepharospasm may be due to a dysfunction of the basal ganglia, but this has not been absolutely proven. Blepharospasm may evolve to include other dystonias as well, such as torticollis.
The risk of developing blepharospasm tends to increase as we get older. The average age that blepharospasm begins is about 55 years. While the risk factors for blepharospasm aren't really well known, it appears that drinking coffee earlier in life may protect against developing blepharospasm later. There may also be an inherited risk, as people with blepharospasm may have other forms of dystonia within their family.
The main treatment of blepharospasm involves injections of botulinum toxin (Botox) into the eyelids and eyebrows. In more severe cases that do not respond to botulinum toxin, surgical treatments like muscle ablation (myomectomy) to weaken the tightening muscles or deep brain stimulation may be helpful. The best treatment of blepharospasm requires close conversation and cooperation with a medical professional like a neurologist.
Source:
Mark Hallett, Craig Evinger, Joseph Jankovic, Mark Stacy. Update on blepharospasm. Report from the BEBRF International Workshop. Neurology 71, October 14, 2008, 1275-1282