Fifty-six patients with either open-angle or low-tension glaucoma who were concurrently taking calcium channel blockers were compared to similar groups not taking such medications for a mean follow-up period of 3.4 years. Serial stereoscopic optic nerve photographs and visual fields of all patients were evaluated for evidence of glaucomatous progression. In patients with low-tension glaucoma, there was a significant difference in the progression of visual field defects, with only two of 18 eyes (11%) of patients taking calcium channel blockers, compared to ten of 18 eyes (56%) of controls showing new visual field defects. Similarly, low-tension glaucoma patients taking calcium channel blocker therapy demonstrated no evidence of progressive optic nerve damage, compared to eight of 18 control eyes (44%). In contrast, patients with open-angle glaucoma taking calcium channel blockers showed no marked difference in the progression of glaucoma, compared to controls. These findings suggest that calcium channel blockers may be useful in the management of low-tension glaucoma.