Objective: To examine the impact of surgical intraocular pressure (IOP) reduction on visual function using various methods to define visual field (VF) progression.

Methods: A retrospective chart review was conducted on consecutive glaucoma patients who underwent surgical IOP reduction between January 1, 2002 and December 31, 2007. All subjects had glaucomatous optic neuropathy, a minimum of 5 preoperative and 5 postoperative VFs, and were followed for a minimum of 2 years both before and after surgery. VF progression was determined using guided progression analysis, linear regression analysis of the visual field index, and individual sensitivity values using Progressor software.

Results: Seventeen eyes of 17 patients (mean age 77.9±9.9 y) were enrolled. Subjects were followed for a mean 5.8±2.4 years before surgery and 4.5±1.5 years after surgery. The mean postoperative IOP (11.3±4.2 mm Hg) and medications (1.3±1.3) were significantly (P<0.001 and P=0.01) reduced compared with before surgery (18.0±3.9 mm Hg, 2.4±0.9, respectively). The number of eyes judged to have VF progression using any method during the postoperative period (3 of 17, 17.6%) was significantly (P=0.03) reduced compared with the preoperative period (9 of 17 eyes, 52.9%). Using visual field index criteria, 8 eyes were judged to have preoperative VF progression and 1 eye had persistent VF progression during the postoperative period. None of the eyes judged to have preoperative VF progression using Early Manifest Glaucoma Trial (n=4) and Progressor criteria (n=1) demonstrated persistent VF progression during the postoperative period. Among eyes with preoperative VF progression, the postoperative slope of mean deviation (-0.21±0.23 dB/y) was significantly (P=0.03) reduced compared with before surgery (-1.01±0.23 dB/y).

Conclusions: Despite differences in the criteria used to define VF progression, glaucoma surgical IOP reduction significantly reduces the incidence and rate of VF progression.