A retrospective study was made of persons with ocular hypertension and normal initial visual fields. Seventy eyes were followed, and glaucomatous visual field defects developed in 25 of these eyes. In eyes with ocular hypertensio, the area enclosed by the central visual field isopter (I2e) was significantly smaller than that previously reported for an age-corrected group of eyes with normal intraocular pressure. In the absence of glaucomatous visual field defects, isopter areas were not releated to cup-disc ratios. Coincident with visual field loss, reductions in both peripheral (I4e) and central (I2e) isopter areas correlated linearly with increases in the cup-disc ratio. Prior to visual field loss, the I4e isopter area wassignificantly smaller among those eyes destined to lose visual field.