Ptosis (or blepharoptosis) is a drooping or falling of the upper eyelid. Complete ptosis is due to complete oculomotor nerve palsy. Partial ptosis is due to a dysfunction of the sympathetic pathway leading to paralysis of Muller muscle.
Note that facial nerve paralysis prevents screwing of the eye.
History and etymology
Ptosis is derived from the ancient Greek word πτῶσις, meaning to fall.
Differential diagnosis
The differential diagnosis for ptosis includes but is not limited to:
- oculomotor nerve palsy
- levator palpebrae superioris muscle injury
- Horner syndrome
- multiple sclerosis
- myasthenia gravis
- Lambert-Eaton myasthenic syndrome
- blepharophimosis
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