Blepharoptosis can be the presenting symptom in a variety of disorders ranging from the relatively common and benign levator dehiscence to debilitating and potentially life-threatening conditions such as myasthenia gravis and aneurysms of the posterior communicating artery. For these reasons, a comprehensive understanding of the clinical and pathophysiological features of the different causes of acquired ptosis is essential in guiding the ophthalmologist toward the appropriate medical and surgical management of these patients (see the following list).