Effect of sildenafil citrate (Viagra) on retinal blood vessel diameter.

Abstract

The present investigation was conducted to evaluate the effect of sildenafil citrate (Viagra, Pfizer Inc., New York, NY) on retinal blood vessel diameter. Double-blind randomized, placebo-controlled, cross-over study. Fifteen healthy male volunteers (mean age 39 years) received 100-mg doses of sildenafil or matching placebo on 2 separate days. Monochromatic fundus photography was obtained in one 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 one artery were measured in a masked fashion from digitized photographic negatives. In comparison with placebo, no statistically significant change in average venous diameter was observed for the superior (analysis of variance [ANOVA], P =.97), inferior retinal temporal vein (ANOVA, P =.73), or the retinal temporal artery (ANOVA, P =.89) after sildenafil treatment. In comparison to placebo, there was no significant difference in the percentage change from baseline in venous or arterial diameter at 1 or 5 hours after sildenafil. The power to detect a 6.5% change in retinal vascular diameter following sildenafil was approximately 80% (P =.05). These data suggest that at the maximum therapeutic dose used clinically (100 mg), sildenafil does not have a significant effect on retinal vascular caliber.