Effect of topical carteolol on the normal human retinal circulation

The effect of topical carteolol 1%, a beta-adrenergic blocker with intrinsic sympathomimetic activity, on the retinal circulation was investigated in 15 normal subjects using laser Doppler velocimetry and monochromatic fundus photography. In a double-masked randomized design, one eye received one drop of carteolol 1% and the fellow eye one drop of placebo. Vessel diameter, maximum erythrocyte velocity, and volumetric blood flow rate were determined in a major temporal vein of each eye just before instillation of the drops and then 120 min later. No significant changes in heart rate or mean brachial artery blood pressure were detected after treatment. Intraocular pressure decreased by 28% in the carteolol-treated eye (P less than 0.0001) and by 15% in the placebo-treated eye (P less than 0.001). No significant changes in vessel diameter, maximum erythrocyte velocity, and volumetric blood flow rate were observed in the carteolol-treated eyes (0.3%, 4.3%, and 3.6%, respectively) or the placebo-treated eyes (0.5%, 5.8%, and 6.7%, respectively).