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The colon cancer drug Avastin is becoming a preferred treatment for wet AMD. ((CBC))

A drug meant to treat cancer is helping to restore sight in people with macular degeneration, say ophthalmologists who are using it without the blessing of the drug's manufacturer.

Age-related macular degeneration (AMD) is the leading cause of blindness in people over age 50.

There are two types of AMD, wet and dry. Wet is the more severe form and last year close to10,000 Canadians were diagnosed with it, said ophthalmologist Michael Potter at the University of British Columbia.

Thanks to word of mouth between ophthalmologists, the colon cancer drug Avastin isbecoming a preferred treatment for wetAMD. Just as Avastin stops the blood supply to cancerous tumours, it stops blood vessels from leaking into the retina and causing blindness.

In some cases, the treatment not only stops the disease but may even reverse the damage to the eyes, said Potter.

"I've seen a lot of people come back and tell me that they see better, often after one or two treatments," said Potter. "Some people tell me they can read a newspaper again."

Avastin costs tens of thousands of dollars when used as a cancer treatment, but the tiny amount injected into the retina for AMD treatment costs a few hundred dollars per shot. At least three injections are needed.

Although Avastin is not licensed for use in eyes and hasn't undergone extensive testing for that purpose, it wasinjected into more than 7,000 eyes around the world last year.

"That's all based on observational data, all based on anecdotal data," said Dr. Alan Cruess, who heads theophthalmology departments at Dalhousie University and the largest hospital in Halifax. "In other words, doctors' impressions, so I'm just sort of inserting a note of caution."

Drug used prematurely, company says

The manufacturer of both drugs, Roche and Genetech, wants doctors to stop using Avastin and wait for the new version, Lucentis, to come on the market.

"Since Avastin was designed for … the treatment of cancer and was not designed for the eye, no ocular safety testing has been done with Avastin," Roche Canadawrote in response to questions from CBC News. "We are concerned about potential safety issues associated with the potential off-label use of Avastin to treat AMD."

Chemically, the two versions of the drug are almost identical. It's expected that U.S. regulators will approve Lucentisnext week, but it won't be available in Canada until at least 2007.

Once Lucentis arrives in Canada, it will cost as much as $2,000 a dose. It's not known if ophthalmologists will continue to offer the cheaper choice of Avastin, or if either drug will be covered by provincial drug plans.

In the meantime, patients in Canada who want the treatment will need to find an ophthalmologist willing to give them the injections, and pay for it out-of-pocket.

"It's cheap at any price because I want to save my vision," Janet Rowles, a patient from Vancouverwho has receivedfourinjections.

So far, it seems to be working for her. "I wantat least to be able to take care of myself, and get around by myself."