Conjunctival autografting

Despite hundreds of controlled studies of dozens of treatments over four decades, conjunctival autografting remains the best surgical procedure for treating both primary and recurrent pterygium today, Donald Tan FRCSG, FRCSE, FRCOphth, FAMS of the National University of Singapore and the Singapore National Eye Centre, told the Second EuCornea Congress.

Recent adjuncts, including fibrin glue and, in some cases, mitomycin-C, can improve outcomes. But recurrence rates and cosmetic results are largely dependent on good surgical technique, he stressed.

Dr Tan pointed out that more patients, especially younger patients, are presenting before pterygia cause clinical symptoms. “Modern pterygium surgery is not just safe surgery with a low rate of recurrence, it is also aesthetic surgery. A good cosmetic outcome is crucial.â€

Sorting out the evidence

With 563 articles published from 1968 through March 2010, pterygium is one of the most studied ocular conditions. That’s one a month for 42 years, Dr Tan pointed out.

Dr Tan identified 79 randomised clinical trials, but comparing results was difficult due to inconsistent methodology. For example, there was no consensus on what constituted recurrence, sample sizes were as small as eight subjects, and follow-up ranged from one to 58 months. Treatment was masked in just 34 per cent of cases.

Nonetheless, A1 level evidence, meaning reliable randomised clinical studies, exists for several major techniques. In five of seven trials, conjunctival autografts produced significantly lower recurrence rates than bare sclera excision, with conjunctival recurrence ranging from zero to 39 per cent. “I do not think it is ethical to perform bare sclera surgery. The recurrence will be worse than the primary,†Dr Tan said.

In 11 trials comparing conjunctival autografts with mitomycin-C, only two showed significant differences in recurrence rates. Dr Tan suggested that MMC is useful in cases of multiple recurrences to control scarring, but suggested using it at the edge of fibrovascular tissue and not on the scleral bed to avoid possible melting.

The literature, including a study by Dr Tan (Tan D et al. Archives of Ophthalmol 1997; 115:1235-40), also show that thicker, less translucent, pterygia are associated with higher recurrence rates.

“It is the fleshiness of the pterygium that is the major risk factor, so you need to remove all the fibrovascular material.â€

Dr Tan’s study also found that surgeon experience matters. Surgeons who had done 10 or more procedures had a five per cent recurrence rate compared with up to 83 per cent for surgeons with no previous procedures.

Essential factors for successful conjunctival grafts include a large graft measuring 8.0mm by 8.0mm, adequate removal of fibrovascular tissue surrounding the pterygium, a thin Tenon’s-free graft obtained with a superficial dissection, Dr Tan said. A stable graft anchored by sutures to the episclera at the limbus above and below, or with fibrin glue, is also critical to graft survival. Fibrin glue also has been shown to cause less pain and reduce healing time, though it has not been conclusively shown to improve graft survival, he added.