Effect of timolol therapy on outflow facility.

A 14-week course of timolol therapy in 38 eyes with open-angle glaucoma produced a statistically significant drop (6 mm Hg) in their mean intraocular pressure but had no effect on the mean coefficient of aqueous outflow. These data are compatible with those of Zimmerman et al. obtained after a single drop of treatment and suggest that timolol reduces intraocular pressure by inhibiting aqueous production.