Histopathologic effect of chronic use of sildenafil citrate on the choroid & retina in male rats.

BACKGROUND & OBJECTIVES Sildenafil citrate is an oral medication used to treat male impotence by the inhibition of phosphodiesterase-5 in the corpus cavernosum and subsequent facilitation of penile erection. Though the ocular side effects of sildenafil have been reported, no information is available on the histopathologic effects of chronic use of sildenafil citrate on the ocular vasculature. The present study was undertaken to study the histopathologic effects of chronic use of sildenafil on the retina and choroid of male rats. METHODS Twelve adult male Wistar rats were used in the study. Six of them were given 8 mg/kg/day sildenafil citrate orally on alternate days, the other six rats were used as control. The animals were sacrificed after 4 wk of treatment, and the eyes were fixed in 10 per cent formalin solution and sectioned after embedding in paraffin. Sections were cut, stained with haematoxylin-eosin (HE) or periodic acid Schiff (PAS) and examined under light microscope. The choroidal capillary diameter was also measured. RESULTS The choroidal capillaries were more dilated in the sildenafil citrate treated group (mean capillary diameter 3.44 +/- 1.68 microm versus the control of 1.78 +/- 1.36 microm, P < 0.001). The retinal layers and their configuration were unchanged in both the groups. INTERPRETATION & CONCLUSION Chronic use of sildenafil citrate can cause dilatation and congestion in the choroidal vasculature of male rats.