Introduction: Sildenafil not only inhibits PDE (phosphodiesterase) 5 in the
corpus cavernosus but also PDE 6 in the eye, which may have ocular side ef
fects.
Case report: We observed improvement of red-green-deficiency in one patient
, which was ophthalmologically verified by different color vision tests. Th
is ocular "erection" is so far unique.
Conclusion: The patients treated with sildenafil should be informed of ocul
ar side effects.