PURPOSE: Sildenafil citrate (Viagra(R)) acts as a relatively specific inhibitor of the type 5 phosphodiesterase isoenzyme (PDE5) in the corpus cavernosum. But, it also has a mild inhibitory effect on PDE6 in the retinal photoreceptor. Therefore, we studied the ocular side effects of sildenafil. METHODS: We tested the visual acuity, intraocular pressure, color vision, visual evoked potential (VEP), electroretinogram (ERG), anterior segment and fundus appearance. All tests were done before and after medication of 50 mg and 100 mg sildenafil, respectively. RESULTS: There was no significant effect of sildenafil on visual acuity, intraocular pressure, color vision, VEP, anterior segment and fundus appearance. ERG changes after 50 mg sildenafil were not significant. The a-wave amplitude of the maximal combined response after 100 mg sildenafil showed significant changes (p=0.021). The b-wave amplitude of the maximal combined response after 100 mg sildenafil showed changes with borderline significance (p=0.059). CONCLUSIONS: In considering the fact that even single dose of 100 mg sildenafil showed changes on ERG, it seems that retinal function in patients receiving sildenafil for a longer period, especially in patients with underlying vascular abnormalities should be monitored by clinical and electrophysiologic tests.
Citric Acid ; Color Vision ; Eating* ; Evoked Potentials, Visual ; Humans ; Intraocular Pressure ; Photoreceptor Cells, Vertebrate ; Retinaldehyde ; Visual Acuity ; Sildenafil Citrate