tokens: METHODS : Forty - three Caucasian patients with primary open-angle glaucoma or ocular hypertension with a mean (+/- SD ) age of 63 (+/- 8 ) years were randomized and crossed over in a double - masked manner to 14 days of treatment with placebo ( morning and evening in both eyes ), timolol solution ( morning and evening in both eyes ), or timolol gellan ( morning in both eyes with placebo in the evening ). On the 13th day of each period , heart rate was recorded continuously during a typical , ambulant 24 - hour period .