Do Drugs for Impotence Cause Blindness
The FDA said that it was looking into cases of impaired vision among men with erectile dysfunction who took sildenafil (Viagra generic, Pfizer). Other cases have been reported in men taking tadalafil (Cialis drug, Eli Lilly ICOS) and vardenafil (Levitra medication, GlaxoSmithKline/Schering-Plough/Bayer AG).
The warning labels for these drugs already mention the possibility of temporary changes in color vision (such as trouble distinguishing blue from green or seeing blue-tinged objects), sensitivity to light, and blurred vision. At issue is the sudden loss of vision when blood flow to the optic nerve is blocked. This condition is called non-arteritic anterior ischemic optic neuropathy (“Naion”). (The blue vision is caused by a reaction in the retina and is not related to Naion.)
The FDA has received 43 reports of Naion: 38 for drug sildenafil, four for tablet tadalafil, and one for generic vardenafil.
Naion is considered a common cause of sudden vision loss in older Americans. Risk factors include diabetes and heart disease, two of the leading causes of impotence.
Naion is sometimes referred to as a stroke of the eye. The optic nerve is a conduit for blood and oxygen to the eye and visual signals to the brain. In Naion patients, the optic nerve narrows suddenly, which cuts off blood and oxygen flow, usually resulting in impaired vision and in rare cases, permanent blindness.
These drugs dilate the arteries, causing increased blood flow in the penis. It isn’t clear whether this action affects blood flow to the eye.
Earlier this year, a report in an ophthalmology journal mentioned seven patients who experienced Naion vision loss within 36 hours of a generic sildenafil dose.
Despite the reports, the link between the drugs and Naion is not clear. There appears to be little evidence that the drugs increase the risk of blindness.
