Effect of sildenafil citrate (Viagra) on retinal blood vessel diameter.
OBJECTIVE
The present investigation was conducted to evaluate the effect of sildenafil citrate (Viagra, Pfizer Inc., New York, NY) on retinal blood vessel diameter.


METHODS
Double-blind randomized, placebo-controlled, cross-over study.


METHODS
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.


RESULTS
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).


CONCLUSIONS
These data suggest that at the maximum therapeutic dose used clinically (100 mg), sildenafil does not have a significant effect on retinal vascular caliber.
Grunwald
Juan E
JE
Scheie Eye Institute, Department of Ophthalmology, University of Pennsylvania, Philadelphia, 19104, USA. juangrun@mail.med.upenn.edu
Metelitsina
Tatyana
T
Grunwald
Lili
L
D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000328:Adult; D001783:Blood Flow Velocity / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure / Q000187:drug effects; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology*; D010781:Photography; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines; D012039:Regional Blood Flow; D012171:Retinal Vessels / Q000187:drug effects*; D000068677:Sildenafil Citrate; D013450:Sulfones; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology*
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases