Topical verapamil and episcleral venous pressure

Objective: To investigate the effect of a single-dose and 2-week administra tion of topical 0.25% verapamil on episcleral venous pressure (EVP) and int raocular pressure (IOP). Design: A prospective, randomized, double-masked, crossover, and placebo-co ntrolled study. Participants: One eye of each of 20 normal subjects received topical verapa mil or placebo. Intervention: The EVP was measured using a pressure chamber episcleral veno manometer, The IOP, EVP, heart rate (HR), and blood pressure (BP) were meas ured at baseline, 1.5 hours after a single drop, and after 2-week, three-ti mes-a-day topical administration of 0.25% verapamil or placebo to one eye. After a 4-week washout period, the treatment to the study eye was reversed, and measurements of EVP, IOP, HR, and BP were repeated. Main Outcome Measures: The EVP, IOP, HR, and BP were measured. Results: Ninety minutes after a single drop, the EVP in the verapamil-treat ed eyes was reduced by 4.8% (P = <0.001) and in the untreated fellow eyes b y 2.4% (P = 0.032), After 2-week topical administration, the EVP was reduce d by 9.5% (P = <0.0001) in the verapamil-treated eyes and by 4.8% (P = 0.00 1) in the fellow eyes. The NP was unchanged in the treated and fellow eyes after a single drop or after a 2-week treatment with placebo. Ninety minute s after topical administration of 0.25% verapamil, the IOP decreased by 7.7 % (P = <0.0001) in the treated eyes and decreased by 3.6% (P = 0.03) in the fellow eyes. After a 2-week administration of topical verapamil, the IOP d ecreased by 12% (P = 0.0001) in the treated eyes and by 7.2% (P = 0.0289) i n the fellow eyes. The changes of IOP in the placebo-treated and fellow eye s were not statistically significant after a single-dose and 2-week adminis tration. After topical administration of verapamil, a contralateral effect on IOP and NP was observed in the fellow, untreated eye. No systemic effect on HR or BP was detected after a single-dose administration of topical ver apamil, There were, however, significant reductions in HR and BP after a 2- week treatment with topical 0.25% verapamil. Conclusion: These results indicate that a single drop and a 2-week administ ration of topical 0.25% verapamil decrease IOP and EVP significantly, with more pronounced reduction after a 2-week treatment than after a single-dose treatment.