Possible Increase in Nonbacterial Infections in Corneal Ulcers Among Contact Lens Users

November 16, 2006

November 16, 2006 — A marked increase in incidence of fungal and amoeba infections cultured in corneal ulcers of soft contact lens users has been noted in surveillance data, researchers reported at the 2006 joint meeting of the American Academy of Ophthalmology and Asia Pacific Academy of Ophthalmology in Las Vegas, Nevada.

According to lead investigator Eduardo C. Alfonso, MD, professor of ophthalmology at the University of Miami in Florida, the data reflect infections that are referred for clinical studies to the ocular microbiology laboratory at the Bascom-Palmer Eye Institute.

"Compared to the previous studies that we reported in 1978, 1980, 1986, and 2000, the current study shows a marked increase in the number of nonbacterial pathogens that we have been culturing in soft contact lens users," Dr. Alfonso said.

The retrospective review, which included data from 1459 cultures collected during 2004 and 2005, showed a 140% increase in the recovery of Acanthamoeba (from 5 to 12 cases/year), and a 500% increase in recovery of fungal pathogens (from 2 to 12 cases/year).

An outbreak of fusarium keratitis cases among contact lens users was reported by Dr. Alfoso as well as by other researchers earlier this year. On April 10, 2006, Bausch and Lomb reported in a news release that a majority of the cases investigated to date had occurred in contact lens wearers using ReNu with MoistureLoc lens care solutions. The company voluntarily initiated a global recall of that product on May 15, 2006.

"The only caveat is that we don't know what the total denominator is for patients who wear contact lenses," Dr. Alfonso told Medscape. "If we assume there has been no difference in that number and we have this increase in the number of patients with amoeba and fungal infections, then this is a significant public health issue."

In current clinical practice, corneal ulcers associated with contact lens use are commonly treated with broad-spectrum antibiotics, often without first performing a culture. "Between 97% and 99% of corneal ulcers have been associated with bacterial infections in this population," said Oliver D. Schein, MD, MPH, professor of ophthalmology at the Wilmer Eye Institute at Johns Hopkins University in Baltimore, Maryland. "According to conventional wisdom, any lesion that does not improve within 2 days of treatment warrants additional attention."

However, this clinical behavior may no longer be acceptable if a higher incidence of amoebae and fungi in corneal ulcers is confirmed by broader studies, which Dr. Alfonso hopes to encourage other organizations to perform.

"We're presenting at the Academy to raise a red flag," Dr. Alfonso said. "Our current practice will not treat these types of infections. If the pathogens are allowed to grow, there may be detrimental effects to the patient's vision by the time the clinician realizes that the infection is not responding appropriately."

Dr. Alfonso's past research on fusarium keratitis was funded by a grant from Research to Prevent Blindness.

2006 Joint Meeting of the AAO and APAO: Abstract PA062. Presented November 13, 2006.

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