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A blepharospasm (from Greek: ''blepharon,'' eyelid, and ''spasm,'' an uncontrolled muscle contraction), is any abnormal contraction or twitch of the eyelid. It is of two types: essential and reflex blepharospasm. The benign essential blepharospasm is 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. In contrast, the reflex blepharospasm is due to any pain in and around the eye. Although there is no simple cure botulinum toxin injections may help temporarily.〔 A surgical procedure known as myectomy may also be useful.〔(【引用サイトリンク】url=https://www.nei.nih.gov/health/blepha/blepharospasm )〕 It is a fairly rare disease, affecting only one in every 20,000 people in the United States. ==Symptoms== * 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 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「blepharospasm」の詳細全文を読む スポンサード リンク
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