Timolol and Epinephrine

• Solutions of 0.1%, 0.25%, and 0.5% timolol maleate were compared with 0.5%, 1.0%, and 2.0% epinephrine hydrochloride in a 17-week, randomized, double-masked study involving 80 patients with primary open-angle glaucoma. Intraocular pressure was lowered to 21 mm Hg or less in 28 of 42 patients treated with timolol but in only 14 of 38 patients treated with epinephrine. Mean intraocular pressure reduction was significantly greater with timolol than with epinephrine. The pressure reduction caused by either drug was maintained during the four months of the study. Tonographic data suggest that timolol lowers intraocular pressure by reducing aqueous formation. Intolerable side effects developed in two patients receiving epinephrine. Timolol was well tolerated by all patients.