The effect of nipradilol, an a-ß blocker, on retinal blood flow in healthy volunteers

Abstract

Purpose. To study the effects of topically applied nipradilol, an a-ß blocker recently developed in Japan as an ocular hypotensive drug, on retinal blood flow (RBF) in healthy volunteers. Methods. Seven healthy volunteers (mean age, 33 years) underwent measurement of RBF using a newly developed stabilized laser Doppler velocimetry system. In a double-blind trial, retinal arterial blood flow, intraocular pressure (IOP), and blood pressure (BP) were measured before and after the instillation of nipradilol or saline every hour for 5 hours. Results. Retinal arterial blood flow and the diameter of the retinal artery significantly (p < 0.05) increased at 4 hours after instillation in nipradilol-treated eyes. Retinal blood velocity did not change significantly. Nipradilol evoked a significant (p < 0.05) bilateral decrease in IOP. Mean BP decreased significantly (p < 0.05) 3 hours after instillation. Ocular perfusion pressure (OPP), calculated from the mean BP and IOP, did not change significantly during the study. Conclusion. Topical nipradilol significantly increased retinal arterial blood flow in healthy volunteers, not through a secondary effect dependent on a change in OPP, but likely through the vasodilatory action of the drug.