Involuntary contraction involving the muscles of the eyelid that causes the eyelid to close. The closure can be brief or prolonged, may be partial or complete, and may involve one or both eyes. When blepharospasm involves both eyes simultaneously, it can cause complete inability to see (temporary blindness). Blepharospasm can occur as an independent, idiopathic condition; as a symptom of brain or nerve damage; or in neurologic conditions such as Parkinson’s disease. in Parkinson’s disease, blepharospasm can be the result of rigidity that affects the muscles of the eyelids and other facial features or a consequence of long-term Levodopa treatment. Bright lights and exposure to environmental irritants such as wind and dust can cause or worsen blepharospasm episodes regardless of their cause.
Most people receive long-term and nearly complete relief from Botulinum toxin therapy (BTX) injections into the eyelids, which paralyze small segments of the muscles. Muscle relaxants such as clonazepam or baclofen and anticholinergic medications such as trihexyphenidyl also provide relief, although they have systemic effects that are sometimes undesired (drowsiness with muscle relaxants and drowsiness or excessive drying of mucous tissues with anticholinergics). If ble-pharospasm is a likely side effect of a levodopa dosage, usually reduction of the dosage is necessary to relieve the blepharospasm fully. Generally when the levodopa dosage is to blame, there are other symptoms (such as nausea and dyskinesia) as well.