Effect of β radiation on success of glaucoma drainage surgery in South Africa: Randomised controlled trial

Abstract

Objective: To evaluate whether β radiation may offer a practical method of improving surgical success for glaucoma drainage surgery in South Africa. Design: Double blind, randomised controlled trial. Setting: Three public hospitals in South Africa. Participants: 450 black Africans with primary glaucoma. Interventions: Trabeculectomy with 1000 cGy β radiation or standard trabeculectomy without β radiation (placebo). Main outcome measures: Primary outcome measure was surgical failure within 12 months (intraocular pressure > 21 mm Hg while receiving no treatment for ocular hypotension). Secondary outcomes were visual acuity, surgical reintervention for cataract, and intraoperative and postoperative complications. Results: 320 people were recruited, β radiation was given to 164; 20 (6%) were not seen again after surgery. One year after surgery the estimated risk of surgical failure was 30% (95% confidence interval 22% to 38%) in the placebo arm compared with 5% (2%) to 10%) in the radiation arm. The radiation group experienced a higher incidence of operable cataract (18 participants) than the placebo group (five participants; P = 0.01). At two years the estimated risks with placebo and β radiation were, respectively, 2.8% (0.9% to 8.3%) and 16.7% (10.0% to 27.3%). Conclusion: β radiation substantially reduced the risk of surgical failure after glaucoma surgery. Some evidence was, however, found of an increased risk for cataract surgery (a known complication of trabeculectomy) in the β radiation arm during the two years after surgery.