Entropion Eyelid Reconstruction

Excerpt

Entropion is an inversion of the eyelid margin, wherein the margin is abnormally rotated towards the globe. This malposition is extremely common and disrupts the normal tear film and protective functions of the eyelid. This malposition often directs the eyelashes posteriorly at the globe, which can cause corneal and conjunctival damage, potentially leading to chronic corneal disease. Entropion can be unilateral or bilateral, involving either the upper or lower eyelids. There are four types of entropion: congenital, involutional, acute spastic, and cicatricial. The most common cause of entropion of the lower eyelid is involutional, while in the upper eyelid it is cicatricial.

The risk of developing entropion increases with increasing age. This is particularly true for involutional entropion, which occurs secondary to age-related weakening and laxity of the muscles and tendons. As we age, the canthal tendons relax, and the eyelid retractors attenuate, causing malposition of the eyelid margin.

Infection, irritation, and inflammation are the primary causes of acute spastic entropion. This condition occurs most commonly after intraocular surgery in patients with unrecognized preoperative involutional eyelid changes. Continual orbicularis oculi muscle contraction causes inward rotation of the eyelid margin. This, in turn, causes corneal irritation due to lash rub, which perpetuates the problem.

Cicatricial entropion is caused by a tarsoconjunctival contracture. Any mechanism that results in increased scar tissue formation, especially in the inner and middle layers of the eyelid, can put an individual at risk for developing cicatricial entropion. Some common risk factors include prior burns, infection, inflammation, connective tissue disease, and trauma, including transconjunctival surgery.