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Ahn, Sung Yul; Park, Hyang Joon

Abstract

The lower eyelid is anatomically composed of three layers consisting of the anterior lamellar, the middle lamellar and the posterior lamellar. The anterior lamellar is composed of skin and the orbicularis muscle. The middle lamellar is composed of the orbital septum and orbital fat. The posterior lamellar is composed of the tarsus and the capsulopalpebral fascia and conjunctiva. The function of the lower eyelid is dependent upon a net result of balanced forces from the tarsal plate, canthal tendon and the orbicularis muscle sling acting on the lower eyelid. These forces provide the intrinsic support required to maintain contact between the lower eyelid and the globe. Forces acting against the intrinsic support of the lower eyelid (extrinsic forces) provide inferior and anterior net vector from the globe. The normal anatomic function and aesthetic appearance of the eyelid is achieved when the intrinsic forces are greater than or equal to extrinsic forces. The lower lid descent and ectropion characterized by unfavorable imbalance are a result of either a decrease in intrinsic forces by weaking the support as in senescence or an increase in extrinsic forces by strengthening the distraction forces as a result of surgery, laser treatment, or trauma. Either way, the extrinsic forces become greater than intrinsic forces. Facial nerve palsy of a leprosy patient causes paralysis of the orbicularis muscle but its antagonistic action muscles (the levator muscle of the upper lid and the capulapalpebral fascia of the lower lid) are functioning resulting in retraction and lapophthalmus of the upper and lower eyelid. Ectropion and retraction in the lower eyelid require various traditional surgical methods such as cantopexy, canthoplasty, lateral tarsal strip procedure as well as medial tarsorrhaphy. In addition to traditional methods, we used a spacer graft consisting of hard palate mucosa or Alloderm. Spacer grafts can be used in either a posterior or anterior method. In the posterior method, the spacer graft is used to create separation between the tarsal plate and the capsulopalpebral fascia / conjunctiva structure. A 5 to 25mm elliptical strip of hard palate mucosa is harvested from the patient and insterted between the two structures. The conjunctiva is dissected in this procedure. In the anterior method, we disinserted the lower edge of the tarsus and the capsulopalpebral fascia. A 5 to 25mm elliptical shaped strip of Alloderm was then inserted between the two structures. The conjunctiva remains intact in this procedure. In addition, a 5 to 35mm Alloderm strip was inserted to immitate the function of the fascia sling and increase the elevation of the lower lid as a spacer graft. The spacer graft with traditional surgical methods was more effective in elevating the lower lid and significantly reducing retraction than using traditional methods alone.