Viagra, surgery and anesthesia: a dangerous cocktail with a risk of blindness.

Since the launch in 1998 of the anti-impotence drug sildenafil (viagra), the American food and drug administration has identified 50 cases of drug-related blindness, the so-called nonarteritic anterior ischemic optic neuropathy. This, very serious, side effect frequently leads to sudden, mostly irreversible loss of vision, and there is no proven effective treatment to cure patients or to prevent recurrence. The mechanism of ischemic optic neuropathy is not clear, but it could be related to the fact that the ophthalmic and central retinal arteries have an autoregulation of their own blood flow without any autonomic nerve supply; vasoreactivity could be lower albeit efficient, and therefore more vulnerable to systemic modifications of the circulation. But decreased visual acuity and loss of visual ability also are, although uncommon, anesthesiological and surgical complications. These data are consistent with the hypothesis that sildenafil, surgery and anesthesia, taken together, could be a potentially dangerous cocktail of risk factors for sudden irreversible loss of vision. To reduce the risk, sildenafil use should be avoided at least one week before surgical operations, since the reported cases of blindness developed 36h after drug ingestion.