Last revised by Patrick J Rock on 18 Dec 2020

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:

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