AIM: To assess the effect of a single dose of Sildenafil citrate on the visual function in men with early-stage age-related macular degeneration(AMD).METHODS: Forty men (mean age 71, range from 55-86 years)with early-stage AMD were prospectively randomized to receive either placebo or Sildenafil citrate (Viagra; Pfizer Inc, New York, NY) 100mg as a single oral dose. Subjects underwent visual acuity, Amsler grid and color discrimination in each eye before and at specific intervals within 9 hours after dosing.RESULTS: Compared with placebo, no pattern of errors were evident in any visual function test following Sildenafil administration. No statistically or clinically relevant changes from baseline were observed in visual acuity or color discrimination. No clinically relevant changes were observed in the Amsler grid. Sildenafil treatment was associated with transient mild or moderate headache and flushing. CONCLUSION: A single 100mg dose of Sildenafil was well tolerated and produced no significant acute visual effects in a sample of men with early-stage AMD.