Abstract
Abstract: :
Purpose: To evaluate the effect of sildenafil citrate (VIAGRA®, Pfizer Inc, New York, NY) on retinal blood vessel diameter. Methods: This was a double-blind, randomized, crossover study performed in 15 healthy male volunteers with a mean age of 39±8 years (± 1SD) who received a 100-mg dose of sildenafil or matching placebo on 2 separate days. Monochromatic fundus photography was obtained in 1 eye and brachial artery blood pressure and intraocular pressure were measured at baseline, 1 hour, and 5 hours after dosing. The diameters of two major temporal veins and 1 artery were measured in a masked fashion from digitized photographic negatives. Results: Average superior retinal vein diameter at baseline, 1 hour, and 5 hours after sildenafil treatment was 19.4±2.6 arbitrary units (AU), 19.6±2.1 AU, and 18.9±2.6 AU; it was 19.2±2.4 AU, 19.3±2.7 AU, and 18.7±2.1 AU after placebo treatment, respectively. Average inferior retinal vein diameter at baseline, 1 hour, and 5 hours after sildenafil was 19.9±2.5 AU, 19.8±2.1 AU, and 19.3±1.8 AU; it was 19.7±2.3 AU, 19.8±1.9 AU, and 19.4±2.0AU after placebo, respectively. Average retinal artery diameter at baseline, 1 hour, and 5 hours after sildenafil was 15.1±2.0 AU, 15.1±1.7 AU, and 14.7±1.7 AU; it was 14.9±1.8 AU, 14.8±1.8 AU, and 14.8±2.0 AU after placebo, respectively. In comparison with placebo, no statistically significant change in average venous diameter was observed for the superior (ANOVA, P=0.97) or inferior retinal temporal vein (ANOVA, P=0.73), or the retinal temporal artery (ANOVA, P=0.89) after sildenafil treatment. For each of the three vessels measured, the power was 80% to detect a mean difference of 6.5% or more between the two treatment groups. Conclusion: These data suggest that at the maximum therapeutic dose that is used clinically (100 mg), sildenafil does not have a significant large effect on retinal vascular caliber.
Keywords: 554 retina • 390 drug toxicity/drug effects • 514 pharmacology