Earlier this year, the 34 million people in the U.S. who wear contact lenses got a scare when a cleaning solution was linked to potentially serious eye infections.

Government researchers investigated Bausch and Lomb's ReNu with MoistureLoc and its connection to Fusarium keratits problems. The product was pulled from shelves after the outbreak in May.

Since then, there have been far fewer infections reported. An authorities did not tie the problem to other brands or products.

A team lead by Dr. Benjamin Park of the Centers for Disease Control and Prevention worked with health officials from 33 states and the U.S. Food and Drug Administration. They confirmed the link to the cleaning product, according to a report in the Journal of the American Medical Association.

"There were 164 confirmed cases of Fusarium keratitis, and we found that users of Bausch and Lomb's MoistureLoc solution were over 20 times more likely to get this infection than people who didn't use this solution," Park said.

He also said the fungus is common in the environment and is often found in bathrooms, sinks and other water sources. In fact, investigators could not find contamination in the manufacturing process or any of the products tested.

But in about one-third of the cases, the infection was so severe that patients needed a cornea transplant to prevent blindness. So Park said it is important that people properly clean and care for their lenses.

Michael Ward of the Emory Eye Center agreed.

"Infections are rare, and they're usually caused by a breakdown in hygienic practice. Of course, the No. 1 thing everyone needs to do is wash their hands prior to ever touching the contact lens," he said.