Computerized image analysis was performed in 46 normals subjects and in 47 cases of ocular hypertension and 48 cases of early glaucoma for optic disc cup depth and optic disc parameters (rim area, cup area, cup volume and cup/disc ratio). The optic disc cup depth was 369.6 +/- 18.2 microns (M +/- SEM) in normal subject, 538.3 +/- 24.0 microns in ocular hypertension cases, 675.0 +/- 24.7 microns in glaucoma cases. The cup depth was significantly different among the three groups. The quotient of horizontal to vertical cup/disc ratio was also significantly different among the groups (1.84 +/- 0.17 in normal subjects, 1.28 +/- 0.05 in ocular hypertension cases, and 1.120 +/- 0.03 in glaucoma cases.) These results demonstrate that the optic disc cup enlarges three-dimensionally in early glaucoma.