Eyelid drooping or palpebral ptosis may be unilateral or bilateral.

This condition may be congenital or acquired. Acquired causes include injury to a nerve (oculomotor nerve or sympathetic nerve fibers), muscle disease or neuro-muscular junction disorder (myasthenia gravis).

Other times palpebral ptosis is due to local lesions of the ligaments and/or muscles that elevate the eyelid (aponeurotic ptosis).

In the examination of the eyelids, characteristics can be identified that allow us to know the mechanism of ptosis.