Outcomes of glaucoma reoperations in the Tube Versus Trabeculectomy (TVT) Study

Abstract

Purpose: To describe the incidence and outcomes of reoperations for glaucoma in the Tube Versus Trabeculectomy (TVT) Study.

Design: Cohort study of patients in a multicenter randomized clinical trial.

Methods: The TVT Study enrolled 212 patients with medically uncontrolled glaucoma who had previous cataract and/or glaucoma surgery. Randomization assigned 107 patients to surgery with a tube shunt (350 mm(2) Baerveldt glaucoma implant) and 105 patients to trabeculectomy with mitomycin C (0.4 mg/mL for 4 minutes). Data were analyzed from patients who failed their assigned treatment and had additional glaucoma surgery. Outcome measures included intraocular pressure (IOP), use of glaucoma medications, visual acuity, surgical complications, and failure (IOP >21 mm Hg or not reduced by 20%, IOP ≤5 mm Hg, additional glaucoma surgery, or loss of light perception vision).

Results: Additional glaucoma surgery was performed in 8 patients in the tube group and 18 patients in the trabeculectomy group in the TVT Study, and the 5-year cumulative reoperation rate was 9% in the tube group and 29% in the trabeculectomy group (P = .025). Follow-up (mean ± SD) after additional glaucoma surgery was 28.0 ± 16.0 months in the tube group and 30.5 ± 20.4 months in the trabeculectomy group (P = .76). At 2 years after a glaucoma reoperation, IOP (mean ± SD) was 15.0 ± 5.5 mm Hg in the tube group and 14.4 ± 6.6 mm Hg in the trabeculectomy group (P = .84). The number of glaucoma medications (mean ± SD) after 2 years of follow-up was 1.1 ± 1.3 in the tube group and 1.4 ± 1.4 in the trabeculectomy group (P = .71). The cumulative probability of failure at 1, 2, 3, and 4 years after additional glaucoma surgery was 0%, 43%, 43%, and 43%, respectively, in the tube group, and 0%, 9%, 20%, and 47% in the trabeculectomy group (P = .28). Reoperations to manage complications were required in 1 patient in the tube group and 5 patients in the trabeculectomy group (P = .63).

Conclusions: The rate of reoperation for glaucoma was higher following trabeculectomy with mitomycin C than tube shunt surgery in the TVT Study. Similar surgical outcomes were observed after additional glaucoma surgery, irrespective of initial randomized treatment in the study.

Trial registration: ClinicalTrials.gov NCT00306852.

Figure 1

Kaplan-Meier plots of the cumulative probability of reoperation for glaucoma in the Tube Versus Trabeculectomy Study after randomized treatment. Tube reoperation rate at 1 year = 1% (n = 101), 2 years = 3% (n = 90); 3 years = 5% (n = 79), 4 years = 9% (n = 67), 5 years = 9% (n = 42). Trabeculectomy reoperation rate at 1 year = 6% (n = 90), 2 years = 13% (n = 74); 3 years = 14% (n = 71), 4 years = 16% (n = 66), 5 years = 29% (n = 39).

Figure 2

Kaplan-Meier plots of the cumulative probability of failure in the Tube Versus Trabeculectomy Study after a reoperation for glaucoma. Tube failure rate at 1 year = 0% (n = 7), 2 years = 43% (n = 3), 3 years = 43% (n = 2), 4 years = 43% (n = 1). Trabeculectomy failure rate at 1 year = 0% (n = 14), 2 years = 9% (n = 9), 3 years = 20% (n = 6), 4 years = 47% (n = 2).