Treatment Outcomes in the Primary Tube Versus Trabeculectomy Study after 3 Years of Follow-up

Purpose: To report 3-year results of the Primary Tube Versus Trabeculectomy (PTVT) Study.

Design: Unmasked multicenter randomized clinical trial.

Participants: Two hundred forty-two eyes of 242 patients with medically uncontrolled glaucoma and no previous incisional ocular surgery, including 125 in the tube group and 117 in the trabeculectomy group.

Methods: Patients were enrolled at 16 clinical centers and were assigned randomly to treatment with a tube shunt (350-mm² Baerveldt glaucoma implant) or trabeculectomy with mitomycin C (MMC; 0.4 mg/ml for 2 minutes).

Main outcome measures: The primary outcome measure was the rate of surgical failure, defined as intraocular pressure (IOP) of more than 21 mmHg or reduced less than 20% from baseline, IOP of 5 mmHg or less, reoperation for glaucoma, or loss of light perception vision. Secondary outcome measures included IOP, glaucoma medical therapy, visual acuity, and surgical complications.

Results: The cumulative probability of failure after 3 years of follow-up was 33% in the tube group and 28% in the trabeculectomy group (P = 0.17; hazard ratio, 1.39; 95% confidence interval, 0.9-2.2). Mean ± standard deviation IOP was 14.0±4.2 mmHg in the tube group and 12.1±4.8 mmHg in the trabeculectomy group at 3 years (P = 0.008), and the number of glaucoma medications was 2.1±1.4 in the tube group and 1.2±1.5 in the trabeculectomy group (P < 0.001). Serious complications requiring reoperation or producing loss of 2 or more Snellen lines developed in 3 patients (2%) in the tube group and 9 patients (8%) in the trabeculectomy group (P = 0.11).

Conclusions: There was no significant difference in the rate of surgical failure between the 2 surgical procedures at 3 years. Trabeculectomy with MMC achieved lower IOP with use of fewer glaucoma medications compared with tube shunt surgery after 3 years of follow-up in the PTVT Study. Serious complications producing vision loss or requiring reoperation occurred with similar frequency after both surgical procedures.