Right mix of conditions may be link to Fusarium

Experts now say the very hallmark of the contact lens cleaning solution-designed to offer a greater degree of comfort for contact lens wearers-turned out to be its downfall. The new claim, which represented a bit of a paradigm shift when the solution was introduced in late 2004, was based on a new combination of surfactants, a "polymer package," as the company's chief medical officer calls it.

Although the situation should not occur with proper use and good hygiene, the company's tests determined that this scenario did not occur in similar solutions, such as MultiPlus, that did not contain this "polymer package," Dr. Levy said.

"What was found, in a massive investigation, was that the Fusarium responsible for these infections was genetically diverse and of a strain common to bathroom sinks and drains," Dr. Levy added.

"In the bathroom, where most people carry out lens care procedures, which is generally a humid environment, Fusarium could potentially contaminate the tip of the bottle as well as the storage case when the solution was left to evaporate, or when the used solution in the case was topped off with fresh solution," Dr. Levy said. "Once the storage system becomes contaminated, the Fusarium is protected by the polymer film. The lens itself could then become contaminated and allow for consistent inoculation of the eye."

However, there is another variable which is patient susceptibility: e.g., corneal compromise, use of topical or systemic steroids, and other risk factors that have been shown to make the eye more vulnerable to infection, he said.

"The polymers in the formula of MoistureLoc, under certain conditions of non-compliance along with patient susceptibility, place patients at disproportionate risk for this rare infection with this product, and for this reason, we have withdrawn the formulation globally," Dr. Levy said.

Usage patterns

The test results were supported by Daniel Schultz, MD, FDA director of devices and the Center for Radiological Health. Dr. Schultz said in a May 15 press conference that, although some cases of fungal keratitis are associated with other products, the MoistureLoc product appears responsible for the recent spike in cases.

"The outbreak of Fusarium keratitis appears to be related to the design of this particular solution and the way in which it's used, and some of the use patterns that occur at the user end," Dr. Schultz explained. "It does not appear to be a problem with the manufacturing and the way in which the product leaves the facility."