By Ben Dobbin The Associated Press

ROCHESTER, N.Y. – Bausch ‘ Lomb Inc. scrambled to reassure investors yesterday as federal health officials try to unravel the mystery of whether its newest contact lens solution is to blame for a flurry of potentially severe eye infections.

The source of an apparent spike in Fusarium keratitis infections linked to the ReNu with MoistureLoc contact-lens solution remains unknown, and it could be weeks before an explanation is found, its chief executive, Ron Zarrella, said yesterday.

The eye-care products maker halted U.S. shipments of the cleaning solution Monday while the Centers for Disease Control and Prevention investigates 109 reports of infection in patients in 17 states dating to June 2005. The company had already cut off shipments from its Greenville, S.C., plant to the Far East in February after dozens of reported infections surfaced in Singapore, Hong Kong and Malaysia.

Company and government scientists have looked at more than 100 possible factors, from chemical ingredients, batch tanks and production lines to packaging and shipping procedures, and “through all of that analysis, we haven’t found a correlation with anything,” Zarrella told analysts during a conference call.

“There’s been theories all the way from, ‘Has the tsunami … hurricanes and the effect of environmental factors created mold levels that are unprecedented?'” Zarrella said. “Right now, we’re trying to deal with the close-in factors of ensuring we don’t have a formula problem or a contamination problem in our manufacturing facilities. And nothing indicates that we do.”

Fusarium is commonly found in plant material and soil in tropical and subtropical regions. Without eye-drop treatment, which can last two to three months, the infection can scar the cornea and blind its victims. Symptoms can include blurry vision, pain or redness, excessive discharge and increased sensitivity to light.

Federal health officials have made no direct link between ReNu and the infections.