In this paper, researchers report the 1-year outcomes of patients enrolled in the Primary Tube Versus Trabeculectomy (PTVT) study.
Study design
The PTVT study is a multicenter, randomized clinical trial that included 125 eyes in the tube group (350-mm2 Baerveldt) and 117 eyes in the trabeculectomy (trab) with adjunctive mitomycin C group (0.4 mg/ml for 2 min).
The study included patients with an IOP between 18 and 40 mm Hg who were on medical therapy and had no history of incisional ocular surgery. The main outcome measures included IOP, glaucoma medical therapy, visual acuity, visual fields, surgical complications and failure (IOP>21 mm Hg or reduced <20% from baseline, IOP≤5 mm Hg, reoperation for glaucoma, loss of LP vision).
Outcomes
The cumulative probability of failure was higher in the tube group than the trab group (17.3% vs. 7.9%) and remained higher with more stringent IOP criteria. Both groups experienced a significant reduction in IOP, though the trab group had a lower IOP (mean 12.4 mm Hg; 46.0% reduction) than the tube group (mean 13.8 mm Hg; 37.5% reduction).
The use of glaucoma medications decreased significantly in both groups, though the tube group had a significantly greater use of therapy compared with the trab group (2.1 vs. 0.9; P<0.001).
Early postop complications were more frequent in the trab group, while late postop complications were comparable between groups. Serious complications requiring reoperation or producing a 2-line or more loss in vision were significantly more common in the trab group (7% vs. 1%; P=0.03).
Limitations
The study population was restricted to patients with no prior incisional surgery, and several patient groups were ineligible for enrollment; therefore, the results are not generalizable. Additionally, the results cannot be applied to patients who receive a different type of tube shunt. Investigators and patients were not masked to the treatment assignment, adding another potential source of bias.
Clinical significance
This study demonstrates that both tube shunt and trab were effective at lowering IOP in patients with no previous ocular surgery. Trabeculectomy had a higher surgical success rate and lower IOP with fewer adjunctive medications, compared with the tube group. However, the tube group demonstrated a more favorable safety profile. Longer follow-up, which is planned by the investigators after 3 and 5 years, is necessary to evaluate relative safety and efficacy between these 2 commonly performed glaucoma procedures.