Previous studies of dark adaptation in glaucoma have been hampered by lack of standardization and poor definition of clinical categories. A new method of testing has been used on ocular hypertensives. A modified Goldmann/Weekers adaptometer and an 11 degree centrally fixated test patch were used to obtain two dark adaptation threshold curves for each subject -- one for blue-green and one for yellow. Results indicate that ocular hypertensives with no field loss and normal fundi have impaired normal subjects. The differences in the thresholds for blue-green were especially noticeable with the blue-green showing the greater difference. The 2.8 minute difference in mean curve cross-over time between normal and ocular hypertensive was also found to be significant. It appears that ocular hypertensives have impaired rod and cone functions, as well as deficient rod-cone interaction.