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.