Two-Year Visual Field Outcomes of the Treatment of Advanced Glaucoma Study (TAGS)

Purpose: to compare visual field (VF) progression between the 2 arms of the Treatment of Advanced Glaucoma Study (TAGS).

Design: Post hoc analysis of VF data from a 2-arm, multicenter, randomized controlled clinical trial.

Methods: A total of 453 patients with newly diagnosed advanced open-angle glaucoma in at least 1 eye from 27 centers in the United Kingdom were randomized to either trabeculectomy (n = 227) or medication in their index eye (n = 226) and followed-up for 2 years with 2 24-2 VF tests at baseline, 4, 12, and 24 months. Data were analyzed for participants with a reliable VF (false positive rate < 15%) at baseline and at least 2 other time points. Average difference in rate of progression (RoP) was analyzed using a hierarchical Bayesian model. Time for each eye to progress from baseline beyond specific cut-offs (0.5, 1, 1.5, and 2 dB) was compared using survival analysis.

Results: This study analyzed 211 eyes in the trabeculectomy first arm and 203 eyes in the medication first arm. The average RoP (estimate [95% credible intervals]) was -0.59 [-0.88, -0.31] dB/year in the medication first arm and -0.40 [-0.67, -0.13] dB/year in the trabeculectomy first arm. The difference was not significant (Bayesian P-value = .353). More eyes progressed in the medication first arm, but this difference was not significant.

Conclusions: There was no significant difference in the average RoP at 2 years.