Sikkerheden af sildenafil er ikke undersøgt hos patienter med kendte arvelige degenerative sygdomme i retina, som Retinitis pigmentosa (et mindretal af disse patienter har arvelige sygdomme i retinas fosfodiesteraser), og dets anvendelse kan derfor ikke anbefales.
The safety of sildenafil has not been studied in patients with known hereditary degenerative retinal disorders such as Retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases) and therefore its use is not recommended.