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B. Wimpissinger, F. Berisha, K. Polak, L. Schmetterer; Effects of Sildenafil on Retinal Blood Flow and Flicker-induced Retinal Vasodilation in Healthy Subjects . Invest. Ophthalmol. Vis. Sci. 2003;44(13):341.
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Purpose: Sildenafil is a specific inhibitor of phosphodiesterase V, which is widely used for the treatment of erectile dysfunction. Sildenafil has been shown to induce vasodilation in several vascular beds via the L-arginine/nitric oxide pathway. The present study aimed to investigate whether sildenafil increases blood flow in the human retina. Methods: In a randomized, double-masked, placebo-controlled, two way cross over study in 12 healthy male volunteers the effects of a single dose of 100mg sildenafil were studied. Subjects received sildenafil or placebo on 2 different study days. After administration of sildenafil retinal hemodynamic parameters were measured every 20 minutes. Retinal vessel diameters and retinal blood velocity were assessed with the Zeiss retinal vessel analyzer and bi-directional laser Doppler velocimetry, respectively. Blood pressure and intraocular pressure were measured with non-invasive techniques. Results: Sildenafil had no effect on mean arterial pressure, pulse rate, intraocular pressure retinal blood velocity or retinal arterial diameters. However, a significant increase in retinal venous diameters (4.7 ± 3.2%; p = 0.0028 versus placebo) and retinal blood flow (15.7 ± 18.0%; p = 0.029 versus placebo) was observed. Viagra had no effect on flicker-induced vasodilation in retinal arteries or veins. Conclusions: Our data indicate that sildenafil increases retinal venous diameters and retinal blood flow in healthy subjects. By contrast, sildenafil does not affect intraocular pressure and flicker-induced retinal vasodilation. Further studies are required to elucidate whether this drug may be therapeutically used in retinal ischemic disease.
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