Treatment Outcomes in the Primary Tube Versus Trabeculectomy Study after 5 Years of Follow-up

Abstract

Purpose: To report 5-year treatment outcomes in the Primary Tube Versus Trabeculectomy (PTVT) Study.

Design: Multicenter randomized clinical trial.

Participants: A total of 242 eyes of 242 patients with medically uncontrolled glaucoma and no previous incisional ocular surgery, including 125 patients in the tube group and 117 patients in the trabeculectomy group.

Methods: Patients were enrolled at 16 clinical centers and randomly assigned 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) > 21 mmHg or reduced < 20% from baseline, IOP ≤ 5 mmHg, reoperation for glaucoma, or loss of light perception. Secondary outcome measures included IOP, glaucoma medical therapy, and visual acuity.

Results: The cumulative probability of failure after 5 years of follow-up was 42% in the tube group and 35% in the trabeculectomy group (P = 0.21; hazard ratio = 1.31; 95% confidence interval = 0.86-2.01). At 5 years, IOP (mean ± standard deviation) was 13.4 ± 3.5 mmHg in the tube group and 13.0 ± 5.2 mmHg in the trabeculectomy group (P = 0.52), and the number of glaucoma medications (mean ± standard deviation) was 2.2 ± 1.3 in the tube group and 1.3 ± 1.4 in the trabeculectomy group (P < 0.001).

Conclusions: Trabeculectomy with MMC and tube shunt surgery produced similar IOPs after 5 years of follow-up in the PTVT Study, but fewer glaucoma medications were required after trabeculectomy. No significant difference in the rate of surgical failure was observed between the 2 surgical procedures at 5 years.

Keywords: Glaucoma surgery; Randomized clinical trial; Trabeculectomy; Tube shunt.

Figure 1.

Flowchart of patient progress in the PTVT Study.

Figure 2.

Kaplan-Meier plots showing the cumulative probability of failure in the PTVT Study. The number of patients at risk at each follow-up visit is shown at the bottom.

Figure 3.

Kaplan-Meier plots showing the cumulative probability of failure in the PTVT Study defining inadequate intraocular pressure (IOP) reduction as IOP > 17 mmHg or reduced < 20% below baseline (A) or IOP > 14 mmHg (B). Inadequate IOP reduction criteria must have been present on 2 consecutive visits after 3 months to qualify as failure. Patients with persistent hypotony, reoperation for glaucoma, and loss of light perception vision are classified as failures. The number of patients at risk at each follow-up visit is shown at the bottom.

Figure 4.

Kaplan-Meier plots showing the cumulative probability of failure in the PTVT Study among patients with preoperative intraocular pressure < 21 mmHg (A), 21–25 mmHg (B), and > 25 mmHg (C). The number of patients at risk at each follow-up visit is shown at the bottom.

Figure 5.

IOP at baseline and follow-up in the PTVT Study. Data are presented as mean ± standard error of the mean. Patients were censored after a reoperation for glaucoma.

Figure 6.

Scatter plot of IOP data in the PTVT Study. Each point represents a patient in the tube group (circle) or trabeculectomy group (diamond) showing the IOP at baseline and 5 years postoperatively. The oblique line indicates no change. Patients were censored after a reoperation for glaucoma.