Pedicle Graft: There are several variations on the basic conjunctival grafting theme, with the most versatile being the rotational conjunctival pedicle or “racquet” graft or flap (Figure 125-6).10,16,17,29 The animal is ideally positioned in dorsal recumbency with the neck slightly ventroflexed and turned slightly away from the affected side. This should put a plane tangential to the corneal axis parallel to the floor. Before surgery, samples are obtained for corneal cytology and bacterial culture and sensitivity. Proper planning of the graft is essential. The superotemporal bulbar conjunctiva is the easiest to harvest, and a lateral canthotomy improves exposure tremendously. The distal end of the graft should extend just ventral to the inferior edge of the ulcer; the pedicle arm must be long enough to easily reach from the hinge region to the distal edge of the ulcer without being stretched too tightly. The pedicle arm should be 3 mm wider than the ulcer to allow for tissue contracture. The surgeon should bear in mind that after preparation of the ulcer bed (see below), ulcer size may increase, so the pedicle width may need to be wider than originally expected.

The incision for development of a rotational pedicle graft begins 1 mm temporal to the limbus at a position tangential to the inferior edge of the ulcer and is continued perpendicular to the limbus (see Figure 125-6, A). The incision is made by lifting the conjunctiva with Colibri forceps; multiple small snips are made with strabismus scissors until the incision is 3 mm longer than the ulcer is wide. The scissors are then introduced into the resulting pocket and directed toward the hinge region while bluntly dissecting Tenon’s capsule away from the underside of the conjunctiva. A second incision is then made with strabismus scissors from the temporal extent of the first incision superiorly and parallel to the limbus. This second incision continues to a point level with a vertical tangent to the temporal edge of the ulcer. Any remaining Tenon’s capsule is now dissected away (Figure 125-7). Finally, a third incision begins at the nasal extent of the first incision and is carried superiorly parallel to the limbus to a point level with a vertical tangent to the nasal edge of the ulcer. The second and third incisions are therefore staggered to create a broad hinge with ample blood supply that will not kink when the pedicle is rotated over the ulcer. At this point, any remaining Tenon’s capsule attached to the pedicle is removed. It is imperative that as much of the remaining Tenon’s capsule as possible is gingerly dissected from the underside of the graft to reduce tension on the graft and postoperative contracture by Tenon’s fibroblasts, both of which are risk factors for graft dehiscence.¹⁴

Preparation of the ulcer bed is crucial to graft success. The ulcer bed, including the stromal walls and Descemet’s membrane, should be gently swabbed with cellulose sponges or a 6400 Beaver blade to ensure that it is free of corneal epithelium. This will improve the chance of adherence of the graft to the lesion. If the ulcer is actively melting, soft ulcer edges should be trimmed out to good cornea that will hold sutures. Before suturing, the graft is rotated into position and laid atop the ulcer; it should easily remain in place without being stretched. If it is too taut, the second and third incisions should be extended to relax the graft. It is important to make sure the pedicle is not twisted as it is rotated; when in its final position, the stromal side of the pedicle should face in toward the anterior chamber, and the epithelial side should face out. The preferred suture is either 7-0 or 8-0 polyglactin 910 placed in a simple interrupted pattern. The first suture should be placed at the 6 o’clock position, with additional sutures every 1.5 to 2 mm along the temporal and nasal edges of the ulcer. To avoid compromising the blood flow, sutures are not placed through the portion of the pedicle arm superior to the ulcer. However, if the ulcer is leaking aqueous humor, one or two sutures should be placed through the pedicle arm and into the superior edge of the ulcer, passing sutures parallel to the pedicle arm to minimize negative effects on blood supply. Sutures should be placed so that the edge of the pedicle abuts the edge of the ulcer without “overriding” onto normal cornea. Otherwise, normal corneal epithelium may proliferate beneath the graft, preventing its adherence (Figure 125-8). After suturing the graft in place, the bare sclera left in the donor site can be covered with adjacent conjunctiva using 6-0 or 7-0 polyglactin 910 in a simple continuous pattern to appose the edges. The donor site for particularly wide pedicles may be too large to cover without placing undue strain on the conjunctiva. In this instance, the scleral bed can be left to heal by second intention. It is the author’s impression that animals with open scleral beds are more painful compared with those in which the bare sclera is covered. In brachycephalic animals, a partial temporary tarsorrhaphy is placed and left up for 1 to 2 weeks to reduce tension exerted by the physiologic exophthalmia.