The Impact of Surgical Intraocular Pressure Reduction on Visual Function Using Various Criteria to Define Visual Field Progression

Abstract

To examine the impact of surgical intraocular pressure (IOP) reduction on visual function using various methods to define visual field (VF) progression. 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. 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). Despite differences in the criteria used to define VF progression, glaucoma surgical IOP reduction significantly reduces the incidence and rate of VF progression.