The authors investigated visual field changes in 28 eyes of 28 adult patients with early-to-moderate chronic open-angle glaucoma (COAG) in whom reversal of glaucomatous disc cupping was documented by computerized image analysis (Rodenstock Optic Nerve Head Analyzer) after intraocular pressure (IOP) reduction from 29.3 (+/- 5.9) to 19.4 (+/- 4.3) mmHg over 34.8 (+/- 24.8) weeks. Humphrey Statpac global indices (mean deviation and pattern standard deviation) improved in direct proportion to the magnitude of IOP reduction even after controlling for the possible influences of learning effect, short-term fluctuation, reliability, duration of IOP reduction, age, and pupil size. The mean visual field global indices (mean deviation and pattern standard deviation) improved in patients with IOP reduction of 40% or greater, in statistically significant contrast to no improvement of mean global indices with IOP reduction less than 35%. The beneficial effect of IOP reduction is apparent in COAG patients with topographical evidence of reversal of cupping.