Topical verapamil and episcleral venous pressure

To investigate the effect of a single-dose and 2-week administration of topical 0.25% verapamil on episcleral venous pressure (EVP) and intraocular pressure (IOP).

A prospective, randomized, double-masked, crossover, and placebo-controlled study.

One eye of each of 20 normal subjects received topical verapamil or placebo.

The EVP was measured using a pressure chamber episcleral venomanometer. The IOP, EVP, heart rate (HR), and blood pressure (BP) were measured at baseline, 1.5 hours after a single drop, and after 2-week, three-times-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.

The EVP, IOP, HR, and BP were measured.

Ninety minutes after a single drop, the EVP in the verapamil-treated eyes was reduced by 4.8% (P = <0.001) and in the untreated fellow eyes by 2.4% (P = 0.032). After 2-week topical administration, the EVP was reduced by 9.5% (P = <0.0001) in the verapamil-treated eyes and by 4.8% (P = 0.001) in the fellow eyes. The EVP was unchanged in the treated and fellow eyes after a single drop or after a 2-week treatment with placebo. Ninety minutes 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 decreased by 12% (P = 0.0001) in the treated eyes and by 7.2% (P = 0.0289) in the fellow eyes. The changes of IOP in the placebo-treated and fellow eyes were not statistically significant after a single-dose and 2-week administration. After topical administration of verapamil, a contralateral effect on IOP and EVP was observed in the fellow, untreated eye. No systemic effect on HR or BP was detected after a single-dose administration of topical verapamil. There were, however, significant reductions in HR and BP after a 2-week treatment with topical 0.25% verapamil.

These results indicate that a single drop and a 2-week administration 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.