Management of Blepharoptosis

Abstract

A thorough understanding of upper eyelid anatomy is essential for the ptosis surgeon. The upper eyelid consists of skin, orbicularis, septum, tarsus, levator, Muller’s muscle, and conjunctiva. The skin and orbicularis form the anterior lamella. Conceptually, the orbicularis may be subdivided according to its topography into pretarsal, preseptal, and orbital components (over the orbital rim and extending to the frontalis muscle superiorly). The orbital septum is a fibrous lamellar structure arising from the periosteum over the superior and inferior orbital rims. In the upper eyelid, the orbital septum fuses with the levator aponeurosis approximately 2 to 5 mm above the superior tarsal border in Caucasians. In Asian patients, the septum extends further inferiorly into the eyelid. Preaponeurotic orbital fat is normally located behind the orbital septum in the preaponeurotic space. The preaponeurotic fat is an important landmark for surgeons as it lies immediately anterior to the levator aponeurosis. The tarsus of the upper eyelid is a firm, dense connective-tissue plate that provides rigidity to the eyelid. The upper tarsal plate measures approximately 10 mm vertically in the center of the eyelid. The tarsal plate is usually 1 mm thick. The levator complex originates from the periorbita of the lesser wing of the sphenoid at the annulus of Zinn. The muscular portion of the levator in adults is approximately 36 mm long, while the aponeurosis is 14 to 20 mm long. The bony attachments of the aponeurosis are via its horizontal expansions, the medial and lateral horns. The lateral horn, which is much stronger than the medial horn, passes through the lacrimal gland and divides it into the palpebral and orbital lobes. The lateral horn attaches to the periorbita of the orbital tubercle and to the lateral canthal tendon. The medial horn is a thin, delicate structure. It attaches loosely with the posterior portion of the medial canthal tendon and curves medially and posteriorly to insert at the posterior lacrimal crest and the adjacent periorbita of the medial orbital wall. Whitnall’s superior transverse ligament (Whitnall’s ligament) is a condensation of the fascial sheaths of the levator muscle located superior to the area of transition of the levator muscle to the levator aponeurosis (musculoaponeurotic junction).