COLOR DOPPLER ULTRASOUND ANALYSIS OF OCULAR CIRCULATION AFTER TOPICALCALCIUM-CHANNEL BLOCKER

PURPOSE: To investigate the effect of topical administration of the ca lcium channel blocker verapamil on intraocular pressure and retrobulba r hemodynamics. METHODS: Tn this randomized, prospective, double-maske d study, we examined the effects of single-dose topical administration of verapamil in ten normal human volunteers by using color Doppler ul trasound imaging to measure hemodynamic parameters. Limitations of thi s study in elude single-dose application of verapamil and relatively s mall sample size. RESULTS: No systemic effect on heart rate or blood p ressure was detected after administration of topical verapamil. The in traocular pressure significantly decreased compared with baseline two hours after topical 0.125% and 0.25% verapamil (P = .015 and .040, res pectively). Pourcelot's ratio, an index of vascular resistance, measur ed in the central retinal artery was significantly reduced after topic al application of 0.125% verapamil (P = .008). The change in Pourcelot 's ratio primarily resulted from an increased end diastolic velocity i n the central retinal artery. No significant difference es compared wi th baseline values were detected in the color Doppler ultrasound measu rements of the posterior ciliary arteries and the central retinal vein two hours after topically administered verapamil. CONCLUSIONS: Topica l administration of verapamil decreases intraocular pressure and alter s ocular hemodynamics, reducing the vascular resistance index in the c entral retinal artery.