A Case Report of Cyanopsia after Taking Sildenafil

ABSTRACT

The emergence of phosphodiesterase (PDE) 5 inhibitors gave rise to the solution for erectile dysfunction, starting with the development of sildenafil. Although their efficacy in treating erectile dysfunction has been shown, the side effects of PDE5 inhibitors, especially sildenafil, must be taken into consideration. A 64-year-old man received 100 mg of sildenafil and experienced blue vision in both eyes; however, after a day or so, his symptoms improved. The symptoms disappeared when he stopped administering sildenafil, but reappeared when the medication was re-administered. Therefore, he discontinued sildenafil treatment and was prescribed udenafil instead. After that, visual adverse events no longer occurred. Causality assessment showed that in this case, sildenafil-induced cyanopsia was “certain” under the World Health Organization-Uppsala Monitoring Center (WHO-UMC) criteria and Korean causality assessment algorithm (Ver.2), and was “probable” according to the Naranjo scale. In addition, sildenafil also led to abnormal visual reactions in other cases. Sildenafil can also inhibit PDE6, which is present in retinal cells, unlike other PDE5 inhibitors. Thus, visual adverse reactions, such as blue vision, are the unique results of sildenafil, and other PDE5 inhibitors may be used to prevent them.