Effect of beta radiation on success of glaucoma drainage surgery in South Africa: randomised controlled trial

Abstract

Objective: To evaluate whether beta 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 beta radiation or standard trabeculectomy without beta 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. beta 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 beta radiation were, respectively, 2.8% (0.9% to 8.3%) and 16.7% (10.0% to 27.3%).

Conclusion: beta 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 beta radiation arm during the two years after surgery.

Trial registration: ISRCTN62430622 [controlled-trials.com].

Fig 1

Flow of participants through trial

Fig 2

Survival times by treatment group after glaucoma drainage surgery in patients with an intraocular pressure ≤21 mm Hg

Fig 3

Intraocular pressures at follow-up plotted against those at baseline by treatment group for glaucoma drainage surgery

Fig 4

Cataract-free survival times by treatment group