Pseudophakic uveitc eyes at risk for traeculectomy failure

Fort Lauderdale, FL-Prior pseudophakia appears to be a risk factor for trabeculectomy failure in eyes with uveitic glaucoma, said K. Sheng Lim, MD, at the annual meeting of the Association for Research in Vision and Ophthalmology.

Dr. Lim's conclusion was based on an analysis of data collected prospectively in a series of 118 eyes followed for a mean of 23 months after undergoing trabeculectomy with mitomycin-C (Kyowa Haikko Kogyo Co. Ltd., Tokyo). Mean IOP fell from 29.8 to 14.9 mm Hg at last follow-up, and the overall complete success rate (IOP.21 mm Hg with no medication or further glaucoma surgery) was 61%. Seventy-eight percent of eyes fulfilled the "qualified" success criteria (IOP.21 mm Hg with topical medication or needling, but no further filtration surgery).

A multivariate analysis was conducted to identify risk factors associated with failure. With six variables examined, only lens status had independent predictive value (p = 0.04). Subsequently, outcomes were further analyzed with eyes categorized according to whether or not they underwent cataract surgery and the timing of that procedure relative to the trabeculectomy. Those results showed that compared with the overall outcomes, complete and qualified success rates were as good in eyes having cataract surgery after trabeculectomy (n = 40; 65% and 80%, respectively) and even better in eyes that had no cataract surgery (n = 34; 74% and 91%).

The eyes included in the study represented a consecutive group of first eye, primary trabeculectomies for uveitic glaucoma. Dr. Barton performed all procedures between May 1998 and April 2004 by using a standard trabeculectomy technique. All cases were done using a fornix-based conjunctival flap with intraoperative mitomycin-C 0.2 mg/ml applied for 3 minutes under a 4 3 2-mm broad rectangular scleral flap and with placement of two to three releasable sutures.

Eyes of patients with juvenile chronic rheumatoid arthritis were excluded, as well as two eyes of patients who received a higher dose of mitomycin-C. The 118 patients in the series were roughly equally distributed by gender. They had a median age of 50 years and included two patients under age 16; about half of the patients were Caucasian and most of the rest were equally represented by blacks and Indian-subcontinent racial/ethnic background.

Underlying uveitic diagnosesThe underlying uveitic diagnosis was chronic or acute anterior uveitis in 48% of eyes. Other diagnoses included panuveitis, intermediate uveitis, Fuchs' heterochromic cyclitis, Posner-Schlossman syndrome, and scleritis. Prior to surgery, the vast majority of eyes had been treated with topical steroids (81%), and an appreciable proportion of patients (27%) had received either systemic steroids or another systemic immunosuppressive agent.

The other variables included in the multivariate analysis of potential risk factors for failure were age, uveitis type, race, presence of bilateral uveitis, and preoperative treatment.

"We were surprised to find that lens status was the only significant predictor, and in particular that race and uveitis type were not independent risk factors," Dr. Lim noted.

He proposed two possible mechanisms that might explain the association between pseudophakia and increased risk of trabeculectomy failure.

"Perhaps conjunctival violation from the previous cataract surgery predisposes to failure of the trabeculectomy, although most of the eyes had corneal incision, or it could be that these patients have more severe uveitis that causes cataract formation earlier, and it is the more aggressive inflammatory process that is the real cause for the failure after trabeculectomy," Dr. Lim said.