BIRMINGHAM, AL — A new study from UAB (University of Alabama at Birmingham) indicates that men with a history of heart attack who use the popular erectile dysfunction medications Viagra (sildenafil) or Cialis (tadalafil) may be at increased risk for vision loss.
The findings, published in the British Journal of Ophthalmology, draw a link between use of the medications and non-arteritic anterior ischaemic optic neuropathy (NAION). NAION, which effects up to 6,000 people annually in the United States, can cause vision loss in one or both eyes.
“We found a strong link between use of Viagra and/or Cialis and the incidence of NAION in men with a history of myocardial infarction, or heart attack,” said Gerald McGwin, Ph.D., associate professor of epidemiology and ophthalmology at UAB and the lead author of the study. “We found similar results in men with hypertension which, while not as dramatic, are substantial enough to indicate that men with a history of either heart attack or hypertension should be warned of the risks of NAION before use of these medications.”
In the summer of 2005, the U.S. Food and Drug Administration (FDA) reported that a small number of men had lost eyesight in one eye after taking Viagra, Cialis or Levitra. At that time, the FDA suggested that men taking the drugs should stop if they experienced a loss of eyesight.
This is the first study to investigate the association between Viagra/Cialis and NAION, according to McGwin. Levitra was not included in the study because it did not appear on the market until after data collection had begun.
Along with his colleagues in the UAB Department of Ophthalmology, McGwin studied 38 men with a diagnosis of NAION and 38 age-matched controls. Men with a history of myocardial infarction who used Viagra/Cialis were ten times more likely to have a diagnosis of NAION than the control group.
NAION has been described as a “stroke of the eye”, caused by insufficient blood flow to the optic nerve head, damaging the nerve and leading to permanent vision loss. McGwin says there is evidence that Viagra and Cialis increase nitric oxide levels at the optic nerve head, which can further diminish blood flow, exacerbating the effects of NAION.
McGwin says that while NAION is relatively rare, the current findings suggest that the large number of men using erectile dysfunction medications could lead to a dramatic increase in the incidence of the condition.
The study was funded by Research to Prevent Blindness, Inc., and the Eyesight Foundation of Alabama. One of the researchers, Cynthia Owsley, Ph.D., is a Research to Prevent Blindness senior scientific investigator.