Anatomic changes in involutional blepharoptosis.

Involutional blepharoptosis is a degenerative process involving the levator aponeurosis. Clinical and histopathologic evidence for involvement of the levator palpebrae superioris muscle has not been firmly established. We examined 20 patients with involutional blepharoptosis who demonstrated additional clinical, anatomic, and histopathologic findings consisting of a dehiscence of the medial limb of Whitnall's ligament, a lateral displacement of the tarsal plate of the upper eyelid, and a fatty degeneration of the levator muscle in the area of Whitnall's ligament. These findings suggest that a primary myopathic process may be involved in some cases of involutional blepharoptosis. The tarsal displacement complicates surgical correction of eyelids with blepharoptosis secondary to this myopathic process.