Short-term changes in the optic nerve head and visual field after trabeculectomy

AIMS OR PURPOSE: To evaluate short-term changes in optic nerve head topography and visual field induced by surgical reduction of intraocular pressure.

A prospective study was performed on 56 eyes of 56 patients with uncontrolled primary open-angle glaucoma despite maximum medical therapy, which underwent trabeculectomy. Optic nerve head evaluations by means of Heidelberg Retina Tomograph, and visual field tests were performed pre-operatively, and at 3 and 6 months after surgery. Differences in intraocular pressure, visual field indices, and Heidelberg Retina Tomograph parameters were evaluated with the t-test for paired data. A linear regression model was calculated to analyze the relationship between intraocular pressure reduction and visual field changes, and optic nerve head changes.

Mean intraocular pressure decreased from 24.4 ± 5.0 mm Hg to 12.1 ± 3.1 mm Hg (month 3, P<0.001), and 10.6 ± 2.8 mm Hg (month 6, P<0.001) after trabeculectomy. Mean retinal nerve fiber layer thickness (baseline, 0.19 ± 0.034; month 3, 0.24 ± 0.039, P=0.05; month 6, 0.21 ± 0.037, P=0.05) showed a statistical significant change compared with baseline values.

In this 6-months study, a significant increase in retinal nerve fiber layer thickness was detected after glaucoma filtration surgery.