Trabeculectomy Can Improve Long-Term Visual Function in Glaucoma.

Purpose To measure the magnitude and direction of visual field (VF) rates of change in glaucoma patients after intraocular pressure (IOP) reduction with trabeculectomy. Design Retrospective, comparative, longitudinal cohort study. Participants Patients with open-angle glaucoma. Methods Patients who underwent trabeculectomy (Trab) with mitomycin-C (74 eyes of 64 patients) with ≥4 reliable VF measurements before and after trabeculectomy and at least 4 years of follow-up before and after surgery were included. Decay or improvement exponential models were used to calculate pointwise rates of perimetric change before and after surgery. A separate comparison (Comp) group with unoperated glaucoma (71 eyes of 65 patients) with similar baseline damage, number of VF tests, and follow-up was used to address possible regression to the mean. Proportions of VF locations decaying or improving before and after surgery in the Trab group, and during the first and second halves of follow-up in the Comp group, were calculated. A multivariate analysis was used to explore variables associated with VF improvement. Main Outcome Measures The rate of pointwise VF change before and after surgery in the Trab group and Comp group. Results Patients in the Trab group were followed for 5.1±2.1 years (mean ± standard deviation) before and 5.4±2.3 years after surgery, with 8.9±4.7 VF tests before and 9.0±4.4 VF tests after surgery. The mean rate of change for all VF locations slowed from −2.5±9.3%/year before surgery to −0.10±13.1%/year after surgery ( P P P  = 0.009). In the Trab group, 57% of eyes had ≥10 improving VF locations postoperatively. Conclusions The results show that trabeculectomy slows the rate of perimetric decay and provide evidence of sustained, long-term improvement of visual function in glaucoma. These findings suggest the possibility of reversal of glaucomatous dysfunction of retinal ganglion cells and their central projections.