Effects of trabeculectomy on the postoperative central visual field as revealed by refraction values

Purpose: To evaluate the effects of trabeculectomy on the rate of deterioration of the central visual field (VF) in patients with normal-tension glaucoma (NTG), as revealed by refraction values.

Study design: Retrospective case series.

Methods: We retrospectively analyzed 28 eyes, including 12 high myopic (spherical equivalent [SE] < - 6 diopters without pathological myopia) and 16 non-high myopic (SE ≥ - 6 diopters) eyes. The rate of VF deterioration (dB/year) was determined using linear regression analysis of 30 -2 and 10 -2 VF tests. The Wilcoxon signed-rank test was used to compare deterioration rates between groups. To assess the influence of initial post-surgery effects, statistical analyses were conducted with and without data from the initial postoperative VF exam.

Results: Trabeculectomy significantly reduced intraocular pressure (IOP) in myopic (14.1 to 9.0 mmHg, P ≤ 0.01) and non-myopic (13.4 to 9.5 mmHg, P ≤ 0.01) eyes. Postoperatively, the 10-2 VF deterioration rate significantly decreased in myopic (- 1.31 to - 0.55 dB/year, P = 0.01) and non-myopic (- 0.80 to - 0.30 dB/year, P = 0.03) eyes. Excluding the first postoperative VF exam, the deterioration rates were - 0.51 ± 0.24 dB/year and - 0.54 ± 0.89 dB/year, respectively, indicating a minor impact on progression assessment.

Conclusions: Trabeculectomy may mitigate central VF deterioration in myopic NTG patients, emphasizing the potential benefits of timely surgical intervention. Further studies are needed to determine the optimal timing for surgery.