Ptosis (pronounced toes-sis, the "P" is silent)

Blepharoptosis, also referred to as ptosis, or droopy eyelid is defined as an abnormal low-lying upper eyelid margin with the eye in primary gaze.  Blepharoptosis can be classified as congenital or acquired.  This differentiation is based on age. A more comprehensive classification is based on etiology and includes myogenic, aponeurotic, neurogenic, mechanical, traumatic, and pseudoptotic. The most common cause of congenital ptosis is myogenic due to the improper development of the levator muscle.  Most cases of acquired blepharoptosis are secondary to aponeurotic causes, such as involutional changes, a disinsertion, or a dehiscence.  Identification of the underlying pathophysiologic mechanism is paramount in instituting optimal treatment.  Some causes of ptosis may be related to cerebral aneurysms, myasthenia gravis, and Horner syndrome.