Walsh & Hoyt: Ptosis

A deficiency of levator tonus produces the clinical sign called blepharoptosis or ptosis. Ptosis may be produced by damage to the motor system controlling eyelid elevation and position at any point along the pathway, from the cerebral cortex to the levator muscle itself. Topical diagnosis of ptosis depends on the character of the deficiency and on evidence of neuropathic, neuromuscular, aponeurotic, developmental, mechanical, or myopathic disease.