Separate and combined effects of timolol maleate and acetazolamide in open-angle glaucoma.

We compared the intraocular pressure-decreasing effect of timolol maleate alone, acetazolamide alone, and combined timolol and acetazolamide therapy in nine patients with bilateral chronic open-angle glaucoma. Timolol decreased intraocular pressure at least as effectively as acetazolamide. The two medications together were more effective than either medication alone, but they did not have a fully additive effect. Episcleral venous pressures and outflow facilities did not vary significantly with any of the three treatment regimens.