Discriminant analysis of quantifiable optic nerve, nerve fiber layer, and visual field measurements were used to assign eye to normal or glaucomatous groups. A database of 185 glaucoma patient with early visual field loss and 54 normal controls was used to develop and test the discriminant function. Parameters that discriminated best between normal and glaucoma were relative nerve fiber layer height and visual field mean defect. Cup-disc ratio, an estimate of optic nerve structure most commonly used by practitioners, was the weakest of the structural parameters to discriminate between normal and glaucoma. The combination of structural and functional measurements performed better than structural or functional measurements alone. When the discriminant function was applied to a group of 124 age-matched ocular hypertensives, 20% were assigned to the glaucoma group. Discriminant analysis of structural and functional measurements increases precision in identification of early glaucomatous damage, provides a probability that glaucomatous damage is present, and may help identify those ocular hypertensives who actually may have early damage.