It is a toxin produced by the bacteria Clostridium Botulinum which weakens muscles by blocking nerve impulses transmitted from the nerve endings of the muscles.
Botulinum toxin is an approved treatment for blepharospasm and hemifacial spasm.
A used It is used to treat blepharospasm with injection of tiny doses of Botulinum toxin several sites above and below the eyes. The sites of the injection will vary slightly from patient to patient and according to physician preference. The injection is usually given on the eyelid, the brow, and the muscles under the lower lid.