9 Repair of Lower Eyelid Retraction
Lower eyelid retraction can result in exposure keratopathy and significant morbidity. The expectations of eyelid retraction repair include restoring normal function and cosmesis to the eyelids. Repair of lower eyelid retraction involves evaluation of the scarring, and specifically, identifying the cause(s) of eyelid shortening. This chapter will review the preoperative assessment and surgical tools required for retraction repair.
This chapter will review eyelid anatomy and the myriad causes of lower lid retraction.
Understanding eyelid anatomy and the relationship between its structure and function is requisite both for determination of the cause of cicatrix and for repair of retraction.
This chapter will outline the operational techniques used in retraction repair.
Periorbital scarring with eyelid retraction can have serious implications on morbidity and contribute to vision loss. Eyelid scarring can result in tissue contracture, ectropion, and entropion, all of which alter normal anatomic eyelid position and prevent protection of the cornea. 1 Retraction repair can restore both function and cosmesis of the eyelids.
The expectations of eyelid retraction repair include restoring normal function and cosmesis to the eyelids. Often, due to preoperative limitations of the existing eyelid structure, excellent cosmesis may not be possible. This should be discussed in detail with the patient in order to avoid postoperative dissatisfaction.
Eyelid retraction repair may require a multistaged series of surgeries, and the patient should be counseled regarding expectations of each intervention.
9.4 Key Principles
The eyelids function to protect the anterior globe and to provide lubrication for the cornea and conjunctiva. The upper eyelid should sit 1 to 2 mm below the superior limbus and the lower eyelid should sit at the inferior limbus. Positioning above (or below, in the case of the lower lid) those landmarks is considered eyelid retraction. Malposition of the eyelids can induce exposure keratopathy due to improper maintenance of the tear film.
The eyelid is typically delineated into two layers, the anterior and posterior lamellae, but some refer to it as trilaminar. The anterior lamella is composed of skin (which does not contain subcutaneous fat) and orbicularis oculi muscle. The orbicularis is innervated by CN7 and functions to close the eyelids; the pretarsal and preseptal portions are responsible for involuntary closure and the orbital portion is responsible for purposeful, forced closure. Scarring of the anterior lamella leads to eyelid retraction and/or eyelid ectropion. The posterior lamella includes the tarsus and conjunctiva. The tarsus is made up of dense connective tissue, measuring between 8 to 12 mm in the upper eyelid and 3.5 to 5 mm in the lower eyelid. 2 These connective tissue plates are continuous with the medial and lateral canthal tendons, providing structure and support for the eyelids. The conjunctiva lines in the inner surface of the eyelid and the globe; it is composed of a non-keratinized mucous membrane that contains both goblet cells and accessory tear glands that secrete the mucin and aqueous components of tears, respectively. Scarring of the posterior lamella can lead to symblepharon, entropion, or eyelid retraction. The middle lamella of the lower lid refers to the tissue in between the two aforementioned layers below the inferior border of the tarsus. This layer includes the orbital septum, preaponeurotic fat pad, and lower eyelid retractors. Scarring of this layer, usually in the setting of previous surgery or trauma, can cause eyelid retraction, entropion, or ectropion.
The eyelids are suspended and supported by the medial and lateral canthal tendons that attach to periosteum of the orbital rim. The medial canthal tendon separates into anterior and posterior portions that surround the lacrimal sac within the lacrimal fossa. The anterior portion attaches to the anterior lacrimal crest of the frontal bone and the posterior portion attaches to the posterior lacrimal crest. While the anterior portion functions to support the medial canthal angle, the posterior portion remains firmly apposed to the globe. 3 The lateral canthal tendon attaches to Whitnall tubercle on the lateral orbital rim approximately 10 mm inferior to the frontozygomatic suture. The insertion of the tendon is approximately 4 mm posterior to the lateral palpebral raphae. The position of the lateral canthal angle is typically 2 mm superior to the medial canthal angle. This anatomic relationship should attempt to be restored in repair after trauma or scarring.
The goals of eyelid retraction repair are to restore function and cosmesis.
The first step in retraction repair involves evaluation of the scarring, and specifically, identifying the cause(s) of eyelid shortening.
Scarring may result from anterior, middle, or posterior lamellar shortening, and ectropion/entropion may be the result of canthal tendon laxity. Often, eyelid retraction is a result of an amalgamation of the above anatomic changes.
Eyelid retraction repair should not be performed in patients who have active eyelid/palpebral conjunctival inflammation, if possible (ocular cicatricial pemphigoid, Graves disease, or Stevens–Johnson syndrome).
It is also suggested that in cases of retraction caused by burns, retraction repair be postponed until at least 12 months after the initial traumatic insult.
9.7 Preoperative Preparation
A few easy tests can be performed in order to garner information about the cause of eyelid retraction. The lower lid distraction test involves grasping the lower eyelid and pulling it anteriorly away from the globe. Distraction of more than 6 mm is considered abnormal and represents lid laxity and often canthal tendon weakness. The snapback test, which also involves pulling the lid off the globe, assesses the speed with which the lid returns to its normal anatomic position. If the patient needs to blink in order to bring the eyelid back into apposition with the globe, the test is abnormal.
The 2-finger test can also be used to determine the cause of eyelid retraction. In this test, two fingers are placed below the eyelid margin and moved superiorly. If retraction is resolved with this movement, the anterior lamella has likely shortened. If the retraction is unchanged, the scarring is likely in the middle or posterior lamellae (Fig. 9‑1, Fig. 9‑2, Fig. 9‑3, Fig. 9‑4). 1
Using two fingers to put lateral traction on the eyelid can be a useful tool to determine the cause of entropion or ectropion. r/f results when the lid margin rolls posteriorly, usually secondary to involutional changes but also as a result of orbicularis spasm or scarring. The inward turning of the lid can result in trauma to the cornea. If the entropion is unchanged after the 2-finger test, the cause is likely middle or posterior lamellar scarring and will require repair with lysis of scar tissue and with use of a lamellar graft. If the entropion is improved with the 2-finger test plus lateral tension on the eyelid, it can often be corrected with a procedure that achieves lid tightening (Fig. 9‑5). 1
Cicatricial ectropion is common in the setting of eyelid retraction due to scarring and involves eversion of the margin away from the globe. This results in evaporation of tears, exposure of the palpebral conjunctiva, and epiphora. If the ectropion is unchanged by the 2-finger test, the cause is likely middle or posterior lamellar shortening and, as aforementioned, requires augmentation of the lamella and scar lysis. If the retraction can be improved with the 2-finger test but not with lateral tension on the lid, ectropion is usually the result of anterior lamellar shortening and requires full-thickness skin grafting. If the eyelid margin can be elevated with the two-finger test and the ectropion resolves with lateral traction, the retraction can be repaired with a tendon tightening procedure (Fig. 9‑1). 1