A prospective study of reversal of glaucomatous optic disc cupping was performed by topographic optic disc analysis using the optic nerve head analyzer (Rodenstock analyzer, G. Rodenstock Instrumente GMBH, Munich, West Germany) in 13 adults with chronic open angle glaucoma. Intraocular pressure decreased from the mean (+/- SD) initial intraocular pressure of 33.2 +/- 8.2 mm Hg to the final intraocular pressure of 16.9 +/- 6.1 mm Hg over 13.6 +/- 10.4 weeks. Mean (+/- SD) cup-disc ratio decreased significantly, from 0.573 +/- 0.207 to 0.499 +/- 0.198, and mean (+/- SD) neuroretinal rim area increased significantly, from 0.913 +/- 0.341 to 1.042 +/- 0.284 mm2. The decrease of mean (+/- SD) cup volume from 0.592 +/- 0.966 to 0.451 +/- 0.703 mm3 was only marginally significant. However, more meaningful was a finding that reversal of cup volume, like reversals of cup-disc ratio and rim area, was directly proportional to the percent IOP reduction (r = .669 for cup volume reversal; r = .626 for cup-disc ratio reversal; and r = .675 for rim area reversal).