Surgical excision of eyelid tumors often produces large defects that may cause significant visual impairment and cosmetic stigma if not treated properly. Reconstruction requires thorough knowledge of anatomy and precise technical execution.
Although there are many reconstructive options in the form of flaps and grafts, the basic principles are: 1) replace lining, support and skin cover; 2) restore corneal protection and lubrication; and 3) optimize the aesthetic outcome.
The eyelids contain skin, orbicularis muscle, tarsal plate and conjunctiva. The upper lid also contains slips from the upper eyelid retractors (see below). The orbicularis oculi muscle includes three separate divisions: pretarsal, preseptal and orbital. The pretarsal orbicularis is primarily responsible for involuntary blinking.
The preseptal orbicularis pumps tear with the lacrimal system and aids in voluntary lid closure. The orbital orbicularis depresses the medial brow and performs protective forced eyelid closure.
Eyelid layers have been arbitrarily divided into the anterior and posterior lamellae. The anterior lamella offers the skin and orbicularis oculi muscle while the posterior lamella offers the tarsus, eyelid retractors and conjunctiva.
The tarsal plates contain vertically oriented Meibomian glands that exit on the lid margin. These glands secrete oils that mix with tears to provide lubrication for the conjunctiva. Medially and laterally, the tarsal plates narrow into fibrous bundles that ultimately converge to create the medial and lateral canthal tendons.
The medial aspects of the upper minimizing lids host the upper minimizing punctae, respectively. Tears generated from the lacrimal gland drain through the punctae into the lacrimal canaliculi and ultimately to the lacrimal sac. The lacrimal sac empties to the inferior meatus through the nasolacrimal duct. Blinking enhances tear drainage by squeezing the lacrimal sac and forcing tears down the nasolacrimal duct.
Upper eyelid positioning is achieved through the action of the levator palpebrae superioris and Müller's muscles (the upper eyelid retractors). The levator muscle arises from the orbital cone and it is innervated by the oculomotor nerve (CN III).
Since it approaches the upper lid, it broadens to the levator aponeurosis and becomes closely approximated with Müller's muscle before attaching towards the upper tarsal plate. Müller's muscle is controlled by sympathetic nervous fibers. These fibers synapse in the superior cervical ganglion and intertwine because they ascend across the internal carotid artery to the cranium.
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