Acquired ptosis: a reexamination of etiology and treatment.

The etiology of acquired ptosis is almost always disinsertion of the levator aponeurosis from the tarsal plate. As opposed to congenital ptosis, where levator resection is required to compensate for muscle weakness, acquired ptosis can be consistently treated with simple levator reattachment. This study examines both the diagnostic and anatomic etiology of acquired ptosis in 80 consecutive patients. Although dermatochalasis, trauma with orbital hematoma, orbital swelling, anophthalmos, and multiple other diverse clinical etiologies were responsible for this condition, the anatomic etiology was identical in 79 of the patients--levator disinsertion. Cadaver studies demonstrate that the levator aponeurosis inserts into the tarsal plate through multiple flimsy, fibrous attachments. Any condition that results in either excess weight to the eyelids or excess muscular pull can disrupt these fibers. A modification of the external approach is described that allows rapid identification of the levator aponeurosis and permits accurate repair. Complete repair was achieved in the majority of the cases, and there were no instances of overcorrection.