ßaps, conjunctival rotation autografting, and as mentioned conjunctival grafts combined with amniotic membrane grafts.

It has been suggested that including limbal stem cells in the conjunctival autograft may act as a barrier to conjunctival cells migrating across the limbus and onto the cornea and help prevent pterygium recurrence. Harvesting of the limbal-conjunctival autograft is similar to harvesting the conjunctival autograft except the dissection is continued 0.5 mm beyond the limbus. The donor is oriented in the recipient bed limbus to limbus. No conclusive evidence exists to date regarding the superiority of limbal-conjunctival autografts over conventional conjunctival autografts [2].

A sliding conjunctival ßap may be harvested from the superior or inferior bulbar conjunctiva to close the bare sclera defect. Reported recurrence rates are one to 5%, but there are only a few reports in the literature where this method has been reviewed [12].

4.3.7Complications in Pterygium Removal

Recurrence is the main complication of pterygium removal and has been reviewed. A more serious, sightthreatening condition is surgically induced necrotizing scleritis. This is a local autoimmune reaction and has been described to occur in the vicinity of previous surgical wounds. The overall incidence of surgically induced necrotizing scleritis (noninfectious and infectious) following pterygium removal has been reported to be 0.2Ð4.5% [19]. Higher rates of scleral necrosis are associated with the adjunctive use of MMC or betairradiation, especially if higher concentrations are used [19]. Because the clinical appearance of progressive scleral melting at the site of pterygium removal may mimic necrotizing scleritis due to autoimmune disease, systemic autoimmune disease must be ruled out in such patients [19].

Scleral necrosis after pterygium removal can manifest as a quiet scleral melt that is discovered on clinical exam, as noninfectious necrotizing scleritis that presents with no anterior chamber reaction, good visual acuity, and mild tenderness with visible scleral melting, and as infectious necrotizing scleritis that presents with severe pain, decreased vision, and perhaps a scleral abcess [19, 20]. A diagnosis of scleral necrosis always necessitates a systemic autoimmune work-up even though the patient

may have a history of a pterygium removal. The workup includes a complete blood count, erythrocyte sedimentation rate and C-reactive protein, antinuclear antibodies, anti-DNA antibodies, rheumatoid factor, cytoplasmic and neutrophilic antibodies, urinalysis, serum uric acid, syphilis serology, and chest X-ray [20]. WegenerÕs granulomatosis is a systemic, life-threatening disorder that must always be kept in mind when a patient in the correct age group presents with necrotizing scleritis. This is a true ophthalmic emergency that requires immediate hospitalization and consult with an internist for intravenous immunosuppression.

Scleral melting not related to active autoimmune disease and as a result of pterygium removal, should be treated medically initially. A combination of oral NSAIDs and topical corticosteroids, as well as topical cyclosporine A (Allergan, Irvine CA) may be effective. If the necrosis worsens on this treatment, the addition of oral corticosteroids may quiet the eye and halt the process. If oral corticosteroids control the necrosis and an improvement is seen, the patient may need to be maintained on oral immunosuppression for up to a year or longer. In this case, the ophthalmologist should work in conjunction with a rheumatologist or transplant immunologist to coordinate an immunosuppressive agent that may be safer for long term use like methotrexate.

If medical management fails and perforation seems likely, surgical management is required to reconstitute the sclera. For this, a variety of materials are available that include conjunctival autografting, amniotic membrane placement, and lamellar patch graft with cornea or scleral tissue. Seng-Ei Ti and Donald Tan reported on the successful use of corneal lamellar grafting to preserve globe integrity in cases of severe scleral melting [19]. Corneal tissue, as opposed to scleral tissue, has some signiÞcant advantages. Because it is thicker and the lamellae are more tightly packed, cornea tissue provides more support to a thinning area of sclera and may reduce the risk of remelting [19].

4.3.8 Summary

Pterygia can be uncomfortable and cosmetically undesirable for our patients. In addition, if they encroach a great deal on the cornea, they can severely affect the visual acuity by producing high amount of irregular astigmatism. We have found that the best technique for

removal is that of conjunctival autografting. It has the lowest recurrence rate in our hands. It does however take practice and young surgeons should pay the closest attention to harvesting a thin graft large enough to cover the entire scleral defect. It is in this way that the recurrence rate will be the lowest, and the procedure will be most successful (Fig. 4.18aÐc).

a

b

c

Fig. 4.18 (a) Preoperative pterygium. (b) One month postoperative pterygium removal with conjunctival autograft. (c) Postoperative photo of the same patient 3 months postoperatively. Photo courtesy of Edward J. Holland

References

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