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Health Canada investigates reports of blindness in Viagra users Last Updated Tue,
26 Jul 2005 16:09:08 EDT
The erectile dysfunction drug Viagra is linked to blindness and vision problems, the department said. INDEPTH: Faint warning: How Canada tracks dangerous drugs "There are two cases that have some commonality but we are still pursuing further information," said Barbara Raymond of Health Canada's Marketed Health Products Directorate. "In fact, we may ultimately find that neither of those cases truly represent the condition that we're concerned about." FROM MAY 27, 2005: Viagra and blindness connection investigated In May, the U.S Food and Drug Administration issued a similar warning for users of Viagra, Cialis and Levitra, which are used to treat impotence and erectile dysfunction. The vision loss, called nonarteritic anterior ischemic optic neuropathy (NAION), occurs when blood flow to the optic nerve is blocked. The condition can cause sudden and painless loss of some or all vision in one or both eyes. Those who experience one episode are at a greater risk of experiencing a second episode affecting the other eye, the Health Canada warning said. While in some cases the condition may improve over time, it can also be irreversible. Howard Pomeranz , a professor of ophthalmology at the University of Minnesota, first sounded the alarm about the possible link in March. He researched cases of 27 men who reported sudden loss of vision after using impotence drugs. "Most of these patients really made emphasis on the fact that they noticed the short period of time of onset of the visual symptoms after they had last used the drug," said Pomeranz, who called the risk minimal considering millions of men use impotence drugs every day with no side-effects. It is difficult to determine if erectile dysfunction drugs cause NAION, since men taking the drugs often have high blood pressure, diabetes or other conditions that put them at increased risk, Health Canada said. Other risk factors for NAION include: Age greater than 50 years.
Last week, the FDA ordered new labelling rules for the erectile dysfunction drugs, advising of the risk of vision loss. Raymond said Health Canada
expects to order similar changes within a few months. The department has requested
more safety data from drug makers.
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Men who take drugs for erectile dysfunction should see a doctor immediately
if they experience sudden vision loss or problems, Health Canada warned Tuesday.
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