Dear Doctor Column, February 20, 2006

Erectile Dysfunction Medications and Vision Loss

Question:

I take Viagra and have read about a possible link between this medication and blindness. Does taking this medication put me at risk for vision loss?

Although the link between Viagra (sildenafil) and other erectile dysfunction medications has gotten a lot of media attention, the risk for permanent vision loss is probably very low for most men. Physicians have written more than 23 million prescriptions for Viagra since the medication was first approved in 1998 for treatment of erectile dysfunction (impotence), the drug’s manufacturer says. Since then, a very small number of men — about 40 — have noted some degree of sudden vision loss in one eye, including rare reports of blindness, after taking erectile dysfunction medication, the Food and Drug Administration (FDA) says. Most of these men (38) were taking Viagra; four were using Cialis (tadalafil); and one was taking (Levitra) vardenafil. In 19 of the men using Viagra, vision loss occurred within 36 hours of taking the drug. Vision loss was permanent or ongoing in 31 men taking Viagra, FDA says.

Most men experienced vision loss due to a condition called nonarteritic anterior ischemic optic neuropathy (NAION), which occurs when blood flow to the optic nerve is blocked. Doctors have known for years that erectile dysfunction medications can temporarily affect the retina and cause short-term vision changes, such as seeing a bluish tinge around objects or having trouble distinguishing between blue and green. NAION, however, is a far more serious problem that can cause permanent vision loss. The optic nerve connects the eyes to the brain, allowing us to see. When blood flow to tiny ocular nerve vessels is blocked, even temporarily, permanent visual damage can result. NAION affects people differently; some may lose a degree of vision and then improve, while others may find vision loss after an episode of NAION remains the same or grows worse. About 15% of people who experience NAION in one eye will develop the condition in the other eye within 5 years.

NAION strikes between 1000 and 6000 Americans a year and is one of the most common causes of sudden vision loss among older adults. Conditions that increase risk for NAION include:

• heart disease
• high blood pressure
• being older than 50 years
• diabetes
• high cholesterol
• smoking
• small optic disc size

NAION and erectile dysfunction share many of the same risk factors, and it is not clear whether medications such as Viagra can actually lead to NAION, or if an underlying medical cause of impotence — heart disease or high blood pressure, for example — contributes to vision loss. Men with erectile dysfunction often have decreased blood flow to the genitals and other areas, such as the heart and brain, which makes them vulnerable to stroke and heart attack. Most of the men who reported vision loss after taking erectile dysfunction drugs had other health problems that increase risk for NAION, including a particular optic nerve structure that can lead to this type of eye damage.

A recent small study conducted by researchers at the University of Alabama at Birmingham, the first investigating the association between erectile dysfunction drugs and NAION, found a link between use of Viagra and Cialis and an increased risk of NAION in men with a history of heart attack or high blood pressure. The association was strongest among men who had suffered a previous heart attack.

FDA notes that it is currently not known whether Viagra, Cialis, or Levitra cause NAION. In 2005, the government agency ordered that labels for erectile dysfunction drugs include warnings about the potential link between sudden vision loss and these medications. FDA recommends that men who develop vision problems in one or both eyes while using erectile dysfunction medications immediately stop taking the drugs and seek medical help right away. Visit the FDA Web site for a list of Viagra’s risks and side effects, as well as more information about the drug’s link to NAION.

If you have a condition such as heart disease or high blood pressure that puts you at risk for NAION, or have ever had vision loss in one or both eyes, you should inform your physician, so he or she can further evaluate your risk for eye damage.