Sildenafil citrate (Viagra), an oral therapy for erectile dysfunction, is a
selective inhibitor of PDE-5, but also PDE-6, which is found in the retina
. This drug has some ocular side effects which are uncommon, dose-dependent
, and reversible. Reported ocular side effects include changes in color per
ception, blurred vision, changes in light perception, electoretinogram chan
ges, and conjunctival hyperemia.