(blepharoptosis) n. drooping of the upper eyelid, for which there are several causes. It may be due to a disorder of the third cranial nerve (*oculomotor nerve), in which case it is likely to be accompanied by paralysis of eye movements causing double vision and an enlarged pupil. When part of *Horner’s syndrome, ptosis is accompanied by a small pupil and an absence of sweating on that side of the face. It may be due to *myasthenia gravis, in which the ptosis increases with fatigue and is part of a more widespread fatiguable weakness. Ptosis is associated with the severe pain and other symptoms of a *cluster headache. It may also occur as an isolated congenital feature or as part of a disease of the eye muscles, when it is associated with weak or absent eye movements.... ptosis
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