More Viagra, Blindness Questions

For weeks the FDA and Pfizer have been negotiating exactly how to change the Viagra label to mention rare, serious cases of eye problems, and even blindness. Now that the maker has agreed to put a new warning on the label, some are concerned about other types of blindness and Viagra, and the problem might be broader than anyone knows, reports CBS News Correspondent Sharyl Attkisson.

"I'm completely blind in one eye and have about 60 percent vision in the other," says one man, who took Viagra twice. The man, who doesn't want to be identified, had a type of stroke in the eye that doctors call "NAION" for nonarteritic anterior ischemic optic neuropathy.

"My eye was having a problem seeing ... like someone pulling a shade down on it," he said.

The FDA is looking into several dozen cases of eye stroke and it's the subject of an unknown number of lawsuits. But a CBS News investigation finds more potential links between Viagra and all kinds of blindness.

CBS analyzed four years of Viagra adverse events reported to the FDA. There were eye problems in more than 800 patients with more than 140 cases of partial or total blindness. These reports alone aren't proof of a direct link, but experts look to them for patterns.

Dr. Alessandra Bertolucci of the New York Eye and Ear Infirmary, treated a 51-year-old patient who permanently lost some eyesight four hours after taking Viagra. She published the case two years ago, while other doctors were writing up their own cases.

"I thought it was important to make the public aware, and the agency in charge of checking of the side effect, aware of this event," says Bertolucci.

Here's where it gets tricky. Many men using Viagra are prone to eye damage to begin with because they have circulation problems. That's why they need Viagra. So the argument is you can't necessarily blame the drug if they go blind.

But Dr. Howard Pomeranz, a neuro-ophthalmologist at the University of Minnesota, wonders if blindness has been written off to diabetes or other factors. When Viagra did play a role? He started investigating eye stroke in Viagra patients seven years ago, and has been a paid expert for both Pfizer and patients suing Pfizer.

"Viagra may be an additional risk factor that is over and above the risk factors they may already have," says Pomeranz.

Most compelling, say some: men with no risk factors at all have gone blind. British doctors published a case five years ago and said back then the potential for blindness should be discussed with all Viagra patients, especially since men using the drug are at high risk.

Pfizer wouldn't comment on that case. They will be changing the Viagra label to mention eye stroke, but insist "no scientific evidence suggests" Viagra causes eye stroke or any other severe vision problems. Pfizer also says: huge clinical studies reveal no serious eye issues, and the FDA is aware of the blindness reports but does not think Viagra caused them.

But one patient is not convinced.

"I don't think I would've taken the medicine at all because I don't think it would be worth taking a chance," he said.

He wishes he'd been warned that improving his sex life might jeopardize his eyesight.

Pfizer insists men reporting blindness would have gone blind anyway — without Viagra.