Focal dystonia due to blepharospasm
The involuntary forcible closure of the eyelid due to spasms.
The first symptoms may be uncontrollable blinking.
Only one eye may be affected initially, but eventually both eyes are usually involved.
The spasms may leave the eyelids completely closed causing functional blindness even though the eyes beneath the lids and vision are normal.
Following torticollis (spasm of the neck muscles), blepharospasm is the next most common form of focal dystonia.
For more information about dystonias, see: Dystonia