A combination of oral and topical beta-blockers with additive effects on intraocular pressure

In a double-masked randomised cross-over study the effect of adding oral propranolol (40 mg X 2) to topical timolol-treatment (0.5% X 2) was evaluated. Ten patients with glaucoma or ocular hypertension (totally 15 pathological eyes and 5 healthy) who had had topical timolol for at least 2 months received the coded oral treatment. A significant decrease of the intraocular pressure (3.68 +/- 0.72 SD, P less than 0.01) was observed in the timolol-treated eyes after the addition of the masked treatment with placebo/propranolol. Also the non-timolol-treated fellow eyes had a significant decrease of the intraocular pressure. It is suggested that this additive effects depends on a loss of efficacy of the topical beta-blocker caused by an increase in the number of beta-receptors and that the oral beta-blocker restores the degree of blocking to a more efficient level.