Ptosis associated with fatty infiltration of Müller's muscle and levator muscle.

Prominent fatty infiltration of Müller's muscle and the anterior levator muscle was noted at the time of surgery in nine of 115 patients undergoing external levator resection for ptosis. This distribution of adipose tissue was confirmed by light microscopy. Fatty infiltration appeared to be a degenerative change found in adults with congenital and acquired ptosis. Preoperatively these patients exhibited moderate to severe ptosis, fair to good levator function, and no elevation of the lid crease. The desired postoperative results were achieved with standard external levator resection and advancement techniques. The fatty appearance may lead to difficulty in identifying customary anatomical landmarks during surgery. With the exception of Horner's syndrome, abnormalities of Müller's muscle have not previously been described in association with ptosis, to these authors' knowledge.