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Left orbicularis oculi, seen from behind.
It normally refers to benign essential blepharospasm, a focal dystonia—a neurological movement disorder involving involuntary and sustained contractions of the muscles around the eyes. The term essential indicates that the cause is unknown, but fatigue, stress, or an irritant are possible contributing factors. In most cases, symptoms last for a few days then disappear without treatment, but sometimes the twitching is chronic and persistent, causing lifelong challenges. In those rare cases, the symptoms are often severe enough to result in functional blindness. The person's eyelids feel like they are clamping shut and will not open without great effort. Patients have normal eyes, but for periods of time are effectively blind due to their inability to open their eyelids.
Although strides have recently been made in early diagnosis, blepharospasm is often initially mis-diagnosed as allergies or "dry eye syndrome". It is a fairly rare disease, affecting only one in every 20,000 people in the United States.
- Excessive blinking and spasming of the eyes, usually characterized by uncontrollable eyelid closure of durations longer than the typical blink reflex, sometimes lasting minutes or even hours.
- Uncontrollable contractions or twitches of the eye muscles and surrounding facial area. Some sufferers have twitching symptoms that radiate into the nose, face and sometimes, the neck area.
- Dryness of the eyes
- Sensitivity to the sun and bright light
Some causes of blepharospasm have been identified; however, the causes of many cases of blepharospasm remain unknown, although some educated guesses are being made. Some blepharospasm patients have a history of dry eyes and/or light sensitivity, but others report no previous eye problems before onset of initial symptoms.
Some drugs can induce blepharospasm, such as those used to treat Parkinson's disease, as well as sensitivity to hormone treatments, including estrogen-replacement therapy for women going through menopause. Blepharospasm can also be a symptom of acute withdrawal from benzodiazepine dependence. In addition to blepharospasm being a benzodiazepine withdrawal symptom, prolonged use of benzodiazepines can induce blepharospasm and is a known risk factor for the development of blepharospasm.
Blepharospasm may also come from abnormal functioning of the brain basal ganglia. Simultaneous dry eye and dystonias such as Meige's syndrome have been observed. Blepharospasms can be caused by concussions in some rare cases, when a blow to the back of the head damages the basal ganglia.
- Drug therapy: Drug therapy for blepharospasm has proved generally unpredictable and short-termed. Finding an effective regimen for any patient usually requires trial and error over time.
- Botulinum toxin injections (Botox is a widely known example) have been used to induce localized, partial paralysis. Among most sufferers, botolinum toxin injection is the preferred treatment method. Injections are generally administered every three months, with variations based on patient response and usually give almost immediate relief (though for some it may take more than a week) of symptoms from the muscle spasms. Most patients can resume a relatively normal life with regular Botulinum toxin treatments. A minority of sufferers develop minimal or no result from Botox injections and have to find other treatments. For some, Botulinum toxin diminishes in its effectiveness after many years of use. An observed side effect in a minority of patients is ptosis or eyelid droop. Attempts to inject in locations that minimize ptosis can result in diminished ability to control spasms.
- Surgery: Patients that do not respond well to medication or botulinum toxin injection are candidates for surgical therapy. The most effective surgical treatment has been protractor myectomy, the removal of muscles responsible for eyelid closure.
- Dark glasses are often worn because of sunlight sensitivity, as well as to hide the eyes from others.
- Stress management and support groups can help sufferers deal with the disease and prevent social isolation.
See also 
- Adams WH, Digre KB, Patel BC, Anderson RL, Warner JE, Katz BJ (July 2006). "The evaluation of light sensitivity in benign essential blepharospasm". American Journal of Ophthalmology 142 (1): 82–87. doi:10.1016/j.ajo.2006.02.020. PMID 16815254.
- Wakakura M, Tsubouchi T, Inouye J (March 2004). "Etizolam and benzodiazepine induced blepharospasm". Journal of Neurology, Neurosurgery, and Psychiatry 75 (3): 506–7. doi:10.1136/jnnp.2003.019869. PMC 1738986. PMID 14966178.
- Goldman, Lee. Goldman's Cecil Medicine (24th ed.). Philadelphia: Elsevier Saunders. p. 2429. ISBN 1437727883.
- Schellini SA, Matai O, Igami TZ, Padovani CR, Padovani CP (2006). "Blefarospasmo essencial e espasmo hemifacial: características dos pacientes, tratamento com toxina botulínica A e revisão da literatura" [Essential blepharospasm and hemifacial spasm: characteristic of the patient, botulinum toxin A treatment and literature review]. Arquivos Brasileiros De Oftalmologia (in Portuguese) 69 (1): 23–6. doi:10.1590/S0004-27492006000100005. PMID 16491229.
- Anderson RL, Patel BC, Holds JB, Jordan DR (September 1998). "Blepharospasm: past, present, and future". Ophthalmic Plastic and Reconstructive Surgery 14 (5): 305–17. doi:10.1097/00002341-199809000-00002. PMID 9783280.
- Blepharospasm – Resource Guide from the National Eye Institute (NEI).
- BEBRF: Benign Essential Blepharospasm Research Foundation – Information about blepharospasm