RECONSTRUCTION OF THE EYELIDS

INTRODUCTION

During the past two centuries, hundreds of surgical procedures have been described for the purpose of eyelid reconstruction, perhaps because of the great value attached to the eyes and vision by our culture. The list of eponymous flaps and techniques is daunting for any student in this field, but rather than overwhelm the reader with their diversity, the goal of this chapter is to present a small number of reliably effective techniques that will address the majority of common clinical situations likely to be encountered. Given the wide audience for this book, this chapter concentrates on those procedures found to be most reproducibly useful among surgeons of different disciplines. Mastery of the concepts and surgical methods herein will also serve as a solid foundation for additional study of advanced procedures that may be best suited for unusual cases.

Physiology of the Ocular Anterior Segment

The mobile nature of the eyelids in ordinary use of the eyes, together with the importance of their supportive role in maintaining the air-tear interface at the cornea for crisp vision and their central role in conveying facial beauty and expression, creates substantial challenges for the reconstructive surgeon. A detailed understanding of the anatomy of the eyelids and ocular adnexa will aid the surgeon in selecting reconstructive approaches that will best restore ocular function while optimizing the aesthetic outcome.

The normal adult eyelids frame an elliptical palpebral fissure measuring 8 mm to 11 mm vertically at the pupillary meridian by 30 mm to 33 mm horizontally. Inside the fissure, the ocular anterior segment composed primarily of conjunctiva, cornea, and iris is visible. The lower eyelid has a smoothly elliptical contour, but the upper eyelid contour is characterized by a tighter medial curvature culminating in an apogee at the medial border of the pupil. The palpebral fissure most commonly slopes upward from medial to lateral so that the lateral canthus is 2 mm higher than the medial canthus. Phenotypic variations exist, and senescence typically causes inferior dystopia of the lateral canthus, whereas the position of the medial canthus is stable throughout adulthood. Minor aberrations in the size of the palpebral fissures, the contour of the eyelids, and the relative positions of the canthi dramatically affect the appearance of the eyes to an onlooker, and asymmetry is immediately apparent.

The upper and lower eyelids rest snugly on the ocular surface in all locations except medially, where the caruncle, composed of sebaceous glands, is interposed and partly covered. Conjunctiva on the surface of the globe is continuous with the conjunctiva lining the inner surface of the eyelids by means of a redundant fornix, most prominently superiorly and inferiorly, where it is supported by attachments to the eyelid retractor muscles and associated fascia. These relationships must be maintained or restored during reconstruction to preserve blink efficiency for corneal wetting and normal tear flow.

Tears are composed of three layers: an outer lipid layer from the meibomian glands in each eyelid; a middle aqueous layer from the main and accessory lacrimal glands located in the superolateral orbit and conjunctival fornices, respectively; and an inner mucin layer from goblet cells in the conjunctiva. Basal tear production is measured by Schirmer paper strips and topical anesthetic. Inadequate production is commonly augmented with artificial tears in older adults. Tear drainage occurs through the lacrimal outflow system in each medial canthus, and purposeful occlusion of outflow with silicone plugs in the lacrimal puncta is also useful to improve the tear film in patients with dry eyes. Minor ocular irritation related to eyelid malpositions after reconstruction can often be improved with these strategies for tear film enhancement.

Excessive tearing or epiphora can be a common problem after eyelid reconstruction, resulting in blurred reading vision and patient annoyance. A balance between tear production and outflow is normally regulated by a reflex response to corneal sensation through a complex neural arc involving cranial nerves V and VII. Primary excess tear production is rare, but reflex overproduction in response to corneal irritation (known as exposure keratopathy ) from eyelid malposition is common. Treatment is aimed at resolving the exposure by improving eyelid position and movement or by augmenting the tear film as previously discussed. Prolonged exposure keratopathy results in corneal scarring or infection with loss of vision.

Interruption of tear drainage from damage to the lacrimal outflow system is common after eyelid reconstruction. The lacrimal puncta are normally in contact with the ocular surface and eversion or ectropion may occur, especially with lower eyelid reconstruction. The lacrimal canaliculi connect the puncta with the lacrimal sac, located posterior to the palpable anterior limb of the medial canthal tendon (MCT). The upper and lower canaliculi are encased in fibers of the orbicularis oculi muscle, which insert onto the lateral wall of the lacrimal sac. Contraction of the orbicularis oculi during blinking pumps the tears into the lacrimal sac. From there, the tears drain to the inferior nasal meatus via the nasolacrimal duct through the maxilla. Surgery in the region of the medial canthus frequently results in epiphora caused by injury to the canaliculi, the lacrimal sac, or the orbicularis oculi fibers that form the lacrimal pump. Primary repair of the canaliculi is obligatory when trauma or tumor excision results in their interruption.

SURGICAL ANATOMY OF THE EYELIDS

Along with a clearer understanding of the physiologic role of the eyelids in maintaining vision, a more detailed review of eyelid anatomy is necessary to grasp the methodology of surgical eyelid reconstruction. Vertically, the palpebral fissure measures 8 mm to 12 mm, such that the upper eyelid rests 3 mm to 4 mm above the center of the pupil and the lower eyelid rests at the inferior limbus. The peak of the upper eyelid margin is medial to the pupil, whereas the lowest point of the lower eyelid margin is lateral to the pupil. Measurement of eyelid position is accomplished with the patient looking in primary gaze (straight ahead) and should be documented preoperatively and postoperatively. The upper eyelid crease is 6 mm to 12 mm above the eyelashes in Blacks and Caucasians (0 mm to 6 mm above the eyelashes in Asians) and is formed by the cutaneous insertion of the aponeurosis of the levator palpebrae superioris muscle. The lower eyelid crease is inconsistently present at approximately 3 mm to 5 mm below the eyelid margin. Additional useful measurements include the range of upper eyelid excursion, typically 10 mm to 15 mm, obtained by measuring the movement of the upper eyelid margin from extreme downward gaze to extreme upward gaze, with the eyebrow fixed with digital pressure from the examiner. The presence and degree of failure of eyelid closure, or lagophthalmos, is also routinely measured, with notation if gentle or forced contraction of the orbicularis oculi is necessary for eyelid competence.

The multilaminar structure of the eyelids varies according to distance from the palpebral fissure. For the upper eyelid below the lid crease, the layers include the epidermal skin with minimal dermis, orbicularis oculi muscle, levator aponeurosis, tarsus, and conjunctiva. Above the lid crease, the layers include skin, orbicularis oculi, orbital septum, orbital fat, levator aponeurosis, Müller’s muscle, and conjunctiva ( Fig. 17.1 ).

The lower eyelid has similar structures, except that the retractor (analogous to the levator muscle) is the capsulopalpebral fascia. This fascia is an extension of the inferior rectus muscle sheath that inserts at the inferior border of the lower eyelid tarsus and causes passive downward movement of the lower eyelid in downward gaze. A sympathetically innervated inferior tarsal muscle analogous to Müller’s muscle is also present in most individuals ( Fig. 17.2 ).

The eyelid protractor is the orbicularis oculi muscle, concentrically arranged around the palpebral fissure. It is commonly divided into three sections. The pretarsal segment overlies the tarsal plates and attaches to the posterior lacrimal crest, deep to the lacrimal sac, together with the posterior limb of the MCT. The gray line of the eyelid margin is formed by the innermost fibers of the pretarsal orbicularis. The preseptal segment overlies the orbital septum and attaches to the lacrimal sac itself and also to the anterior limb of the MCT. Laterally, the pretarsal orbicularis contributes to the lateral canthal tendon, together with tendinous fibers from the tarsal plates. The pretarsal and preseptal orbicularis fibers together form the lateral canthal raphe. Finally, the orbital outermost segment of the orbicularis overlies the orbital rim and interdigitates with the frontalis muscle superiorly and the superficial musculoaponeurotic system inferiorly. Superiorly, there is a sub-brow fat pad between the orbital orbicularis muscle and the frontal periosteum of the superolateral orbital rim. Inferiorly, an analogous fat pad, the suborbicularis oculi fat, is between the orbital orbicularis and the maxillary periosteum.

The lateral canthal tendon anchors the tarsal plates posteriorly and superolaterally to Whitnall’s tubercle inside the orbital rim. The lateral eyelids are thus kept snugly against the globe in all positions of gaze. Medially, the MCT is the centerpiece of medial canthal anatomy. The MCT has an elastic lateral portion that supports the lacrimal canaliculi and then splits into anterior, superior, and posterior limbs, all of which blend with the lacrimal sac fascia. The thick anterior limb inserts on the maxillary bone, and the superficial preseptal orbicularis muscle fibers insert on the anterior limb ( Fig. 17.3 ). The superior branch extends to the lacrimal sac apex and covers the anterosuperior portion of the lacrimal sac. The thin posterior limb forms the anterior fascia of the pretarsal orbicularis muscle and inserts on the posterior lacrimal crest formed by the lacrimal bone. It acts as a horizontal supporting band that posteriorly directs forces generated by the pretarsal muscle fibers. The lateral portion of the MCT invests the fragile lacrimal canaliculi. Reconstruction at either canthus must re-create the deep attachments of the canthal tendons inside the orbit to avoid symptomatic eyelid malpositions.

Posterior to the orbicularis oculi muscle is the orbital septum, a multilayer fascia separating the superficial eyelid and skin adnexa from the orbit. It extends from the arcus marginalis of the orbital rim to the levator aponeurosis and capsulopalpebral fascia before their insertion on the tarsal plates. It is nondistensible and avascular, making it an excellent surgical landmark.

The tarsal plates are composed of dense connective tissue and house the meibomian glands that produce oil for the tears. The upper eyelid tarsus is 10 mm to 12 mm in height and tapers medially and laterally. It is 16 mm to 20 mm in length and approximately 1 mm thick. The lower eyelid tarsus is 4 mm to 5 mm in height but similar in length and thickness to the upper tarsus. Both are anchored medially and laterally to the orbital rim by the canthal tendons, as described before. The posterior surface in each case is lined with densely adherent conjunctiva.

In the upper eyelid the levator muscle originates posteriorly in the orbit and is redirected by Whitnall’s ligament to insert on the anterior surface of the tarsus as a broad aponeurosis. Whitnall’s ligament runs horizontally from the trochlea to Whitnall’s tubercle and acts as a pulley for the levator. The levator muscle and aponeurosis are invested loosely by orbital fat anteriorly until the aponeurosis fuses with the orbital septum at or above its insertion at the tarsus. It is innervated by the oculomotor nerve (cranial nerve III).

The sympathetically innervated Müller’s muscle arises from the posterior surface of the levator at the junction of the muscle and aponeurosis and inserts onto the superior border of the tarsus. The insertion is associated with a rich vascular plexus. Loosely adherent conjunctiva lines the posterior surface of Müller’s muscle. Suspensory ligaments from the levator support the superior conjunctival fornix.

In the lower eyelid the capsulopalpebral fascia arises from the inferior rectus, splits to envelope the inferior oblique muscle, and then inserts at the anterior inferior border of the tarsal plate. It has few attachments to the skin and so the lower lid crease is poorly formed. The capsulopalpebral fascia is loosely attached to the inferior forniceal conjunctiva posteriorly and the orbital fat anteriorly. The sympathetically innervated inferior tarsal muscle arises from the posterior surface of the capsulopalpebral fascia and inserts at the inferior tarsal border. Whereas loss of the normal attachments of the levator and Müller’s muscle to the upper lid tarsus causes ptosis, loss of the attachments of the capsulopalpebral fascia and inferior tarsal muscle to the lower lid tarsus commonly causes rotational instability of the lower eyelid and entropion.

The vascular supply to the region comes from the internal and external carotid systems. Branches from the ophthalmic artery in the posterior orbit pass forward as the anterior ciliary arteries and contribute to the superior and inferior tarsal arcades in the eyelids ( Fig. 17.4 ). Branches from the facial artery supply the medial and lateral canthus and also contribute to the eyelid vascular arcades. Risk for eyelid vascular compromise exists if the arteries are interrupted both medially and laterally.

For the purposes of eyelid reconstruction, the anatomic layers can be divided into anterior and posterior lamellae. The anterior lamella is composed of the skin and eyelid protractor, the orbicularis muscle; the posterior lamella is composed of the conjunctiva, tarsus, and eyelid retractors. The orbital septum can be considered a middle lamella and is not typically reconstructed; however, prevention of contracture and tension in the orbital septum can avoid severe compromise to eyelid excursion postoperatively.

ANESTHESIA

Topical tetracaine 1% or proparacaine 0.5% eye drops are used to anesthetize the ocular surface and are repeated as needed for patient comfort. Frequent lubrication of the cornea with ophthalmic petrolatum ointment or hydroxypropyl cellulose eye drops will also improve patient comfort during and after surgery.

Local anesthesia with monitored sedation is usually preferred, although reconstruction of the lacrimal drainage system or very large defects may require general anesthesia. Lidocaine 1% with 1:100,000 concentration of epinephrine is mixed 1:1 with bupivacaine 0.75% for most cases. The addition of 150 units of hyaluronidase per 10 mL of local anesthetic greatly facilitates more rapid distribution and also enhances regional vasoconstriction from epinephrine. A 27- or 30-gauge needle is preferred for superficial infiltration, and the injection technique should steer clear of subcutaneous vessels and the orbicularis muscle to avoid ecchymosis. Injection of small aliquots deeply inside the lateral orbital rim is helpful for lateral canthal tendon reconstruction, and subconjunctival infiltration with 1 mL to 2 mL is also generally useful in full-thickness eyelid reconstruction. An infratrochlear nerve block may be used for surgery in the medial canthus, and cocaine 4% topically is expedient for intranasal anesthesia needed for passage of lacrimal stents.

RECONSTRUCTIVE OBJECTIVES

The primary objective of eyelid reconstruction is to re-establish functional eyelids that protect the eye and permit normal vision. Normal tear film maintenance necessary for corneal clarity and patient comfort is a corollary prerequisite. The most important secondary goal is normal or improved appearance because the periocular region is critical in interpersonal relations. Loss of eyelid tissue is caused most commonly by surgical excision of neoplasms but also by burns, trauma, necrotic infections, congenital colobomas, and medical interventions (such as steroid injections, cryotherapy, and irradiation). Surgical objectives include the following:

• 1.

  Nonkeratinizing mucosal epithelium to line the inside of the reconstructed eyelid to protect and to wet the cornea

• 2.

  Rotationally stable eyelid margin with a mucocutaneous junction to protect the eye from skin, lanugo hairs, and lashes

• 3.

  Posterior apposition to the globe in all areas of the reconstructed eyelid

• 4.

  Moderately flexible, firm connective tissue frame to provide support and shape for the eyelid

• 5.

  Adequate protractor muscle to close the eyelids, to provide a normal blink, and to assist in posterior apposition of the eyelid to the eye

• 6.

  Lack of orbital septal contracture or attachments that restrict eyelid excursion

• 7.

  Supple, thin skin that permits normal eyelid excursion

• 8.

  Adequate levator muscle function to provide upper lid clearance of the pupil

• 9.

  Appropriate height and shape of the reconstructed eyelid and the medial and lateral canthi to maintain symmetry with the contralateral side

• 10.

  Minimally visible scars

The single most useful reconstructive strategy to achieve most of these objectives is conversion of vertical surgical tension to horizontal tension in the eyelids whenever possible.

Surgical planning is facilitated by conceptually dividing the eyelids into anterior and posterior lamellae. The anterior lamella is composed of the skin and the orbicularis muscle; the posterior lamella is composed of the conjunctiva, tarsus, and eyelid retractors. For full-thickness defects, both lamellae usually require reconstruction. In these cases, at least one of the reconstructed lamellae typically must include a blood supply. Commonly used, reliable surgical techniques are listed in Tables 17.1 and 17.2 and involve various flaps and grafts. Selection will depend on the size, location, depth, and configuration of the defect. Some superficial defects may require only reconstruction of the anterior lamella, and choice of flap or graft is primarily dependent on the need to restore a mobile, cosmetically satisfactory eyelid or to restore normal canthal position. When necessary, reconstruction of the lacrimal tear drainage system is accomplished concomitantly.