ROBERT SIEGEL, host:
This is ALL THINGS CONSIDERED from NPR News. I'm Robert Siegel.
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And I'm Michele Norris.
The Food and Drug Administration is studying reports that Viagra and similar drugs for treating impotence may cause a serious vision problem. Determining whether there is a link will be difficult. The eye condition is rare, and many men taking the drugs also have high blood pressure or other health problems that already make them prone to the disorder. NPR's Joanne Silberner has more.
JOANNE SILBERNER reporting:
Doctors call the condition non-arteritic anterior ischemic optic neuropathy. Think of it as a stroke in the lining of the back of the eye. Something suddenly shuts down blood flow, and in up to 25 percent of cases, that eye loses sight. People who have high blood pressure, diabetes or high cholesterol are at risk. There are no effective treatments. The March issue of the Journal of Neuro-ophthalmology described seven Viagra takers who developed visual problems in one or both eyes. None went fully blind. For six of the seven, the problem occurred within a day of taking Viagra. Jonathan Trobe of the University of Michigan is the editor of the journal that published the report.
Mr. JONATHAN TROBE (Editor, Journal of Neuro-ophthalmology; University of Michigan): It brings up the question of whether the Viagra is acting as a precipitant. In other words, you wouldn't have had this happen had you not taken the Viagra, and the Viagra kind of tips you over.
SILBERNER: A connection is plausible.
Mr. TROBE: It's plausible because Viagra has an effect on blood flow, and the problem that these patients have run into with loss of sight and stroke, that's an issue of blood flow, not enough blood flow.
SILBERNER: But the plausibility isn't perfect. Trobe explains that in the penis, the drug works mainly on veins that carry blood to the heart. In the eyes, the problem is in tiny arteries that carry blood the other way. Recognizing a link is difficult.
Mr. TROBE: These were all patients who had the kinds of risk factors that make you prone to having this sort of stroke in the eye happen even if you're not taking Viagra.
SILBERNER: An FDA spokesman says the agency has so far received reports of 38 cases of the neuropathy associated with Viagra, four with Cialis, and one with Levitra. Meanwhile, Pfizer, the manufacturer of Viagra, estimates that 23 million men worldwide have used its product, and the condition did not show up in premarket testing in 13,000 men. Neuro-ophthalmologist Norman Schatz of the Bascom Palmer Eye Institute in Miami says ophthalmologists can do a simple eye exam to see whether someone's internal eye structure makes them prone to the disease. And any man who's had the neuropathy in one eye will certainly want to avoid erectile dysfunction drugs. But is Schatz certain of the connection between the neuropathy and erectile dysfunction drugs?
Dr. NORMAN SCHATZ (Bascom Palmer Eye Institute): No. No. You know, we're at seven patients and anecdotal stories, and nothing that--nobody's done controlled studies, nobody's looked at this in a scientific fashion to say, `We know the final answer.'
Determining the answer will require a large-scale study. Joanne Silberner, NPR News.
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