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Optic nerve head circulation after topical calcium channel blocker
P A Netland1, G T Feke, S Konno
1Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston 02114, USA.
Journal of Glaucoma
|June 1, 1996
Summary
Topical verapamil effectively lowers intraocular pressure and enhances optic nerve head blood flow in healthy individuals. These positive effects on ocular circulation were observed even with placebo, suggesting a crossover effect in normal subjects.
Area of Science:
- Ophthalmology
- Pharmacology
- Cardiovascular Science
Background:
- Glaucoma and ocular hypertension are significant concerns, often managed with medications that reduce intraocular pressure (IOP).
- Optic nerve head (ONH) circulation is crucial for maintaining visual function, and impaired blood flow is implicated in various optic neuropathies.
Purpose of the Study:
- To evaluate the impact of topical verapamil, a calcium channel blocker, on IOP and ONH capillary blood speed.
- To determine the dose-dependent effects of verapamil on ocular hemodynamics in healthy subjects.
Main Methods:
- A randomized, double-masked study involving 12 healthy participants.
- Administration of three concentrations of topical verapamil (0.063%, 0.125%, 0.25%) or placebo to fellow eyes.
- Assessment of IOP and ONH capillary blood speed using laser Doppler flowmetry at baseline and 90 minutes post-instillation.
Main Results:
- Topical verapamil significantly reduced IOP compared to baseline, with greater reductions observed than with placebo.
- A dose-dependent increase in ONH capillary blood speed was noted with verapamil, reaching statistical significance at 0.25%.
- No systemic effects on heart rate or blood pressure were detected, and placebo also showed some IOP reduction and blood speed increase, indicating a crossover effect.
Conclusions:
- Topical verapamil demonstrates efficacy in lowering IOP and improving ONH capillary blood speed in normal subjects.
- The observed crossover effect with placebo warrants consideration in future study designs and clinical interpretations.
- Verapamil presents a potential therapeutic option for conditions involving elevated IOP and compromised ONH circulation.