Ptosis of the upper eyelids is a well-known complication of most forms of ocular surgery. The incidence of ptosis following glaucoma surgery is reported to range from 6 to 12%. The etiology has not been entirely established; however, it is believed to be multifactorial, and several contributing factors have been identified. Identification of the etiology is important since this will often dictate the management. The ptosis may be transient, resolving within days, or persistent. The management of acquired ptosis following glaucoma surgery is critical since surgical over correction can expose a filtering bleb and lead to serious complications, including endophthalmitis. Transient ptosis following surgery is more common than persistent ptosis and may recover within 12 to 72 hours. It may be caused by anesthetic, lid edema, or hematoma formation in the eyelid or muscle. A retrobulbar or peribulbar block with lidocaine may affect the levator muscle. Similarly, direct infiltration of the eyelid will block the distal fibers of the oculomotor nerve. The primary factors postulated to cause ptosis include muscle or nerve damage from local block, a superior rectus bridle suture or corneal traction suture, general anesthesia, eyelid edema, traction applied by the speculum, and levator aponeurosis dehiscence. The lid speculum has been identified as a cause of ptosis regardless of the type of ocular surgery. Superior forces are placed on the upper eyelid while a superior bridle suture or corneal traction suture directs forces downward. These opposing forces may cause a stretching or frank dehiscence of the levator aponeurosis. One study specifically looked at the role of the bridle suture and did not find a significant contribution to ptosis development versus those cases that did not use a bridle suture. Rather, lid edema, neuromuscular block, and the lid speculum itself were identified as causative factors. It has been suggested that prolonged eyelid edema leads to disinsertion of the levator aponeurosis in susceptible populations, such as the elderly. This has not been borne out in other studies; however, some of the same factors that cause prolonged edema may also cause persistent ptosis, specifically inflammation.
Asian Blepharoplasty: The Indian Perspective