NEW YORK (CNN/Money) - Pfizer is in talks with the Food and Drug Administration to update the label on Viagra, its blockbuster treatment for sexual dysfunction, to reflect cases of vision loss in a small number of patients, the company said Friday.

"Pfizer is in discussions with the Food and Drug Administration to update the Viagra label to reflect these rare ocular occurrences," the company said. "Viagra has a strong safety profile and remains an effective medication that benefits millions of people."

The FDA said it is investigating reports that Viagra and erectile dysfunction drugs from two other companies may cause vision loss especially in people over 50. An FDA spokeswoman said that a connection between between the drugs and blindness has not been proven and the administration has no plans to pull any of the drugs from the market.

The blindness, known as non-arteritic anterior ischemic optic neuropathy or, NAION, "Is a condition that occurs in patients with diabetes and cholesterol." Said FDA spokeswoman Susan Cruzan. "There is a very small number of reports and we definitely can't say that this is a cause and effect."

In addition to the 38 Viagra reports, Cruzan said the administration is also investigating four reports regarding Cialis, the erectile dysfunction drug by Eli Lilly & Co., and one report about Levitra, the ED drug by Schering-Plough. Cruzan said that Lilly voluntarily updated its Cialis label.

Pfizer said that its 103 clinical trials with 13,000 Viagra patients found no reports of NAION. Outside of clinical trials, Pfizer said, reports of visual loss from NAION were "extremely rare" among users of Viagra, which was approved in 1998.

"There is no evidence showing that NAION occurred more frequently in men taking Viagra than men of similar age and health who did not take Viagra," the company added.

Analysts downplayed the news. Barbara Ryan, analyst for Deutsche Bank North America, said today's sell-off of Pfizer stock was an overreaction.

"I just don't think it's a big deal," said Ryan. "There certainly isn't any evidence linking Viagra with these reports. There is a risk with this form of blindness from diabetes and cardiovascular disease, and those are also risks for erectile dysfunction or impotence, which is also why people take Viagra."

Al Rauch, analyst for A.G. Edwards & Sons, said the reports are no cause for alarm.

"It seems like it's not really a major association," said Rauch, adding the FDA is investigating less than 50 reports of blindness out of 20 million Viagra patients worldwide, while 6,000 people suffer from the condition each year.

Pfizer (down $0.65 to $28.25, Research) stock fell about 2 percent in morning trading.

A family member of Rauch owns Pfizer stock and A.G. Edwards owns Pfizer securities. Ryan does not own Pfizer stock, but Deutsche Bank North America does.