In a prospective, randomized, double-masked study, primary open-angle glaucoma patients were treated twice daily with either betaxolol 0.5% or timolol 0.5%. Patients received a pretreatment baseline examination following a 2 week washout period; they were then examined after 3 and 6 months of treatment. Each examination included visual field measurements with an Octopus automated perimeter and intraocular pressure measurement. The visual fields of the betaxolol group showed on the average a pronounced tendency toward improvement (MD decrease of 2.05 dB); visual fields in the timolol group showed a slight tendency toward improvement (MD decrease of 1.56 dB). The difference between these 2 trends after 6 months was statistically not significant (p greater than or equal to 0.05, U-test). Both drugs lowered intraocular pressure, there was no significant difference between the two drugs (p greater than or equal to 0.05, U-test).