"Bausch & Lomb's top priority is the safety of our customers, and we want them to have complete confidence in our products," said the eye-care product maker's chief executive, Ronald Zarrella.
The Food and Drug Administration said Bausch & Lomb suspects that ReNu with MoistureLoc solution's unique disinfecting and moisturizing agents "in certain unusual circumstances can increase the risk of Fusarium infection."
"While FDA is still concluding its scientific evaluations ... at this time we recognize that Bausch & Lomb has proposed the formulation as the potential root cause of the increased relative risk of Fusarium keratitis associated with use of the ReNu with MoistureLoc product," the agency said in a statement.
"There does appear to be an association between the formulation itself as well as certain use patterns in creating this higher-than-normal incidence of these particular infections," Dr. Daniel Schultz, director of the FDA's Center for Devices and Radiological Health, said in a conference call with reporters.
Schultz did not elaborate on "use patterns" other than to say they combined "somewhat unique circumstances."
"At this point, our scientific conclusion is pretty clear, that the association is in fact just with the MoistureLoc solution," Schultz said.
The Centers for Disease Control and Prevention said Friday that the number of confirmed cases of Fusarium keratitis in the United States has climbed to 122, most of them contact-lens wearers who reported using Bausch & Lomb's newest cleaner, which was introduced in late 2004
The company halted U.S. sales of MoistureLoc on April 13 after the CDC said it was investigating an unusual spike in infections in Americans using the product. The outbreak first surfaced in the Far East in the fall and infections have showed up most recently among contact-lens wearers in Europe.
The fungus is commonly found in plant material and soil in tropical and subtropical areas. Without eye-drop treatment, which can last two to three months, the infection can scar the cornea and blind its victims. At least eight U.S. patients have required cornea transplants.
Extensive federal inspections of its factory in Greenville, S.C., where MoistureLoc was made for U.S. and several Asian markets, have not turned up evidence of "contamination, tampering, counterfeiting or sterility failure," Zarrella said in a statement.
"That leads us to conclude that some aspect of the MoistureLoc formula may be increasing the relative risk of Fusarium infection in unusual circumstances," he said. "We are continuing to investigate this link, but in the meantime, we're taking the most responsible action in the interests of our customers by discontinuing the MoistureLoc formula."
The FDA plans to release the results of its investigation of the factory in the next few days. Schultz said the inspection would likely find some manufacturing issues but downplayed their significance in explaining the outbreak.
The company said the recall is limited to MoistureLoc and does not involve other solutions in its ReNu line, including the older and more widely used MultiPlus brand, which some victims reported using.
Of the more than 30 million Americans who wear contact lenses, about 2.3 million use MoistureLoc, which accounted for $100 million in global sales last year. Another 11 million people use the MultiPlus solution.
Some eye specialists theorized last week that MoistureLoc's new disinfectant, Alexidine, in combination with novel moisturizing agents, could have played a role in the outbreak.
"The general thinking now is we're seeing a loss of disinfecting capability as this solution absorbs into the lens," said Dr. Arthur Epstein, chairman of the American Optometric Association's contact lens and cornea section. "Somehow the disinfectant in the real world isn't doing what it's supposed to do."
Bausch & Lomb also makes contact lenses, ophthalmic drugs and vision-correction surgical instruments and generates more than $2 billion in annual revenues. The company has not issued guidance for 2006 and said it cannot estimate how the recall will affect results this year.
The fallout has helped to undermine its stock, which peaked at $87.89 in July after more than two years of robust growth. Its shares, which have sunk 35 percent this year, rose $3.91, or 8.8 percent, to $48.35 in late morning trading on the New York Stock Exchange. The company employs 12,400 people worldwide.