Scleral Melt & Ischemia Surgical Steps

Anesthesia

Topical anesthesia is preferred. After prep and drape of the eye and insertion of a lid speculum, drops of non-preserved epinephrine 1/1000 (Hospira, Inc., Lakes Forest, IL) are instilled on the ocular surface to achieve vasoconstriction for hemostasis, and 2% lidocaine gel (AstraZeneca LP, Wilmington, DE) is applied for anesthesia.

Traction Suture and Exposure

                Fig. 2

A 7-O double armed Vicryl suture is placed as a traction suture at 2 to 3 mm from the superior and inferior limbus with episcleral bites (Fig. 2). The eye is rotated by hanging a locking needle holder to allow adequate exposure of the bulbar sclera where the ischemia and melt is most pronounced.

Incision

Removal of Necrotic Tissue and Calcium Plaque

                  Fig. 4A                                     Fig. 4B

The scleral melt area is further debrided to remove all unhealthy necrotic tissue (Fig. 4A). If there is calcified plaque (e.g., in chronic scleral melt) it can simply be removed by superficial lamellar dissection using a #64 blade (Fig. 4B). The goal is to restore a clean host bed that may reveal the underlying uveal tissue.

For Repair of Scleral Ischemia in Acute Chemical/Thermal Burns

                 Fig. 5A                                Fig. 5B

                Fig. 5C                                     Fig. 5D

After removal of necrotic tissue (Fig. 5A, 5B, 5C), the ischemic zone is first covered by a layer of cryopreserved amnion graft to protect the remaining sclera using 10-O nylon interrupted sutures (Fig. 5D) or fibrin glue (see below).

For Repair of Scleral Tissue Loss using a Lamellar Corneal Graft

                  Fig. 6A                                     Fig. 6B

                  Fig. 6C                                    Fig. 6D

For eyes showing scleral melt, a notable loss of scleral tissue can be supplanted by lamellar corneal tissue. After measuring the dimension of the scleral defect, the corneal graft is stripped off the endothelium and the epithelium using a Q-tip. A free-hand lamellar graft is created by using scissors and a super blade to match the scleral defect size (Fig. 6A). This lamellar corneal graft can be secured to the scleral bed without sutures using fibrin glue; it is hard to place sutures if the melt extends to the equator. This gluing is achieved by drying the scleral bed with a Weckcel, applying the thrombin (watery, colorless) solution to the bare sclera (Fig. 6B), and then by applying the fibrinogen (viscous, tawny) solution to the concave stromal surface of the lamellar corneal graft (Fig. 6C). The lamellar corneal graft is then flipped to cover the scleral defect, and attached to the sclera using a muscle hook to smooth and spread the fibrin glue evenly underneath (Fig. 6D).

Tenonplasty

                Fig. 7A                                    Fig. 7B

                Fig. 7C                                    Fig. 7D

The subconjuctival Tenon tissue is carefully dissected from the episcleral space and from the overlying conjunctiva tissue, and prepared as a pedicle graft (Fig. 7A). Such a Tenon graft is easily stretched to cover a large area. The size of such a Tenon graft is contingent upon the size of the ischemic area to be covered. It is advisable to cover at least a part, if not all, of the defect by either using 10-O nylon sutures with solid episcleral bites to the healthy sclera (Fig. 7B) or fibrin glue. The thrombin (watery, clear) solution is applied on the top of the corneal graft (Fig. 7C) and the fibrinogen (viscous, tawny) solution is applied to the inner surface of Tenon’s capsule. Using two 0.12 forceps, the Tenon is stretched to cover the scleral defect area, and held for at least 5 seconds (Fig. 7D). A muscle hook is then used to spread and smooth the fibrin glue underneath. 
 

Transplantation of Amnion Graft

                 Fig. 8A                                       Fig. 8B                                   Fig. 8C

                Fig. 8D                                        Fig. 8E                                  Fig. 8F

The cryopreserved amnion graft is peeled from the nitrocellulose filter paper using two 0.12 forceps and laid down onto the scleral melt area with the sticky, stromal surface facing down to cover the entire defect (Fig. 8A). The membrane is flipped in half so one half of the stromal surface will be facing up (Fig. 8B). The thrombin (watery, clear) solution is applied to the surgical bed/defect (now covered by Tenon’s capsule) (Fig. 8C) and fibrinogen (viscous, tawny) solution is applied to the stromal side of folded membrane (Fig. 8D). Next the membrane is flipped back on the bed/defect and a muscle hook is used to spread the fibrin glue into an even and thin layer underneath the amnion graft (Fig. 8E). The above steps are repeated to secure the other half of the membrane. After a short time (less than 30 sec) of polymerization, check the strength of the adhesion by lifting each corner of the membrane with 0.12 forceps. If easily detached, apply the two fibrin glue components directly onto the bed/defect and spread the glue and smooth the membrane again using a muscle hook. Trim the excess membrane and fibrin glue from the edges (Fig. 8F).

About Sutures:

If fibrin glue is not used, both lamellar corneal graft and Tenon’s pedicle graft can be secured by interrupted 10-O nylon sutures. The cryopreserved amnion graft can be secured using several interrupted 10-O nylon sutures on peri-limbal bulbar conjunctiva and by 8-O Vicryl sutures in a mattress fashion, parallel to the fornix, with solid episcleral bites to seal the fornix border.

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