Reconstruction of the medial canthal area of the eyelids provides a number of challenges because of the complex anatomy which includes the junction of the upper and lower eyelids, glabella, and upper nasal side wall. The area contains multiple contours, a variety of skin thicknesses and textures, and anatomic limitations including eyebrow cilia and the underlying lacrimal system. Consideration of these factors as well as the aesthetic importance of this region all contribute to the challenges of its reconstruction.

The lacrimal outflow system, including puncta, canaliculi, and lacrimal sac, should be carefully examined prior to beginning reconstruction as they may be minimally or significantly damaged during tumor removal. Repair with mono- or bicanalicular silicone stents should be performed as required. If the system is grossly absent or unable to be reconstructed, consideration for Jones tube placement may take place after months to years of tumor-free interval.

The medial canthal tendon (MCT) is important not only in its support of the proximal lacrimal system but also in maintaining the position of the medial commissure of the eyelids (Fig. 1.5). When the MCT is absent, the medial eyelid commissure, whether native or reconstructed, should be sutured to the periosteum of the medial orbital wall in a location that provides good eyelid to globe apposition (i.e., toward the posterior lacrimal crest). Anterior misplacement may result in damage to the lacrimal sac or a gap between lids and globe leading to focal exposure keratopathy, as demonstrated in ▶ Fig. 4.1.

When defects or flaps involve the glabellar region, consideration must be given to the brow cilia. Absent medial brow cilia can result in a significant cosmetic deformity. Flaps involving the glabellar area should be created with care to avoid medialization of the brow or shifting cilia with the flap to a discontinuous area where they would be an aesthetic concern.

An additional consideration when navigating the glabellar region is the presence of the supraorbital and supratrochlear neurovascular bundles. These provide sensory innervation to the forehead and anterior scalp as well as blood supply to many of the flaps used in medial canthal reconstruction. Hence, recognition and preservation of these structures is important when possible.

Medial canthal defects are prone to cutaneous web formation and hypertrophic healing. Webbing is a particular risk because of the concave geography of the region. This concavity can be preserved by placement of a full-thickness suture attaching the flap overlying the concavity to the underlying periosteum. Hypertrophic scarring occurs in part because the tissue filling the defect is often a thicker skin type than that native to the eyelid. It is, therefore, critical to minimize risk factors for postoperative wound hypertrophy, such as judicious use of subcutaneous polyglycolic acid sutures used to relieve wound tension, and consideration of cutaneous suture material which is least likely to promote inflammation, such as nylon or polypropylene. ▶ Fig. 4.2, ▶ Fig. 4.3, and ▶ Fig. 4.4 demonstrate medial canthal defects that healed with undesirable scars and webbing.

Periorbital skin cancers frequently involve the medial canthal region; hence, it is important to have a variety of medial canthal reconstruction techniques in one’s armamentarium. A variety of flaps and grafts can be used alone or in combination to achieve a satisfactory functional and aesthetic outcome.

Secondary intention healing by allowing wound granulation to occur without reconstruction is an
excellent option for many small defects in the medial canthal region. Generally, defects that overlie or are just superior to the MCT are in the ideal location for this. Granulation of more inferiorly located defects may cause traction on the lower eyelid resulting in ectropion and eyelid retraction. Besides the patient avoiding an additional surgical procedure, an advantage of this passive technique is that no additional incisions are made to create flaps; hence the surface area of surgically manipulated tissue is minimized. A disadvantage is that deeper defects can take several weeks to epithelialize, which some patients find frustrating. ▶ Fig. 4.5, ▶ Fig. 4.6, ▶ Fig. 4.7, and ▶ Fig. 4.8 show examples of medial canthal defects that healed by secondary intention.

Direct closure of a small defect in the medial canthal area is sometimes possible. Care must be taken to avoid closure that would result in web formation; hence, creation of a small flap is often a better option in this risky area.

Full-thickness skin grafts are an option for the repair of myocutaneous defects that are of limited depth. Full-thickness skin grafts of the size needed for the periorbital area are generally easy to harvest and these survive well because of the rich vascular supply of this region. However, full-thickness skin grafts from distant sites are rarely the best option for the medial canthus due to several reasons. Skin thickness, texture, and color are usually not as good a match as that of a regional flap. Furthermore, it is not possible to control the vectors of tension on a skin graft during healing. In contrast, a flap can be created to distribute tension in a direction parallel to relaxed skin tension lines, thus increasing cosmesis and decreasing the risk of eyelid retraction and other unwanted tissue distortions. However, full-thickness skin grafts are sometimes a useful adjunct in large defects where flaps cannot completely close the defect or in patients with skin disorders or other skin cancers in the areas surrounding the defect that would prevent the use of flaps. ▶ Fig. 4.9 and ▶ Fig. 4.10 demonstrate the use of these grafts to repair medial canthal defects.

Rotational and advancement flaps are highly useful in medial canthal reconstruction. They replace missing tissue with skin of similar color and compatible texture. The thickness of the flap can be controlled to match the depth of the defect by careful dissection of the subcutaneous tissue. Flaps should be created to control skin tension vectors to maximize the aesthetic appearance and prevent undesired tension on the lid margin. In general, consideration should be given to creation of a flap originating superior to the defect, as contractile forces during healing will result in upward traction on the wound. If the flap is created inferior to the defect, there is risk of downward traction with resulting lower eyelid ectropion and retraction. The subsequent sections will discuss several flaps that are useful for medial canthal defects of various sizes and depths.