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Nonbacterial pathogens increasingly found in contact lens-related ulcers
Historical trends show an increase in the occurrence of fungal pathogens in contact lens wearers, researcher says.
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Over the past 20 years, there has been an increase in the occurrence of nonbacterial pathogens associated with cosmetic soft contact lens corneal ulcers, according to Eduardo C. Alfonso, MD.
“Fungal pathogens were four times more likely than free-living amoebae to be recovered from contact lens keratitis in 2004 and 2005 [than in previous studies], and these results suggest that empiric treatment with an antibiotic will not adequately treat increasing numbers of nonbacterial corneal ulcers in contact lens wearers,” Dr. Alfonso said at the American Academy of Ophthalmology meeting in Las Vegas.
“Bacteria remained the most common pathogens recovered from contact lens wearers in South Florida, but nonbacterial pathogen frequency among contact lens wearers increased from 3.1% in 1986 to 64.7% in 2004 to 2005, and this is approximately a 20 times increase,” he said.
Dr. Alfonso presented data that he and colleagues collected at Bascom Palmer Eye Institute in Florida to document the prevalence of nonbacterial pathogens, including fungi, among cosmetic contact lens users.
“Contact lens-related corneal ulcers, as we know, are commonly associated with bacterial pathogens, and therefore the treatment with broad-spectrum antibiotics has been effective in this disease,” he said. “More recently there has been a low prevalence of fungal and acanthamoebal ulcers associated with contact lens wear.”
Historical data
The purpose of the analysis was to identify historical trends in nonbacterial pathogens in cosmetic contact lens users, Dr. Alfonso said. He and colleagues reviewed microbiology laboratory records from January 2004 to December 2005 and analyzed the rate of culture-positive keratitis and the distribution of microbial pathogens in contact lens wearers and noncontact lens wearers.
Dr. Alfonso and colleagues also compared the 2004-05 data with historical data from three previous studies performed at Bascom Palmer containing data from January 1969 to December 1977, from January 1977 to September 1982, and from January to December 2000.
The age of patients in the records reviewed from 2004 and 2005 ranged from 13 to 95 years; 52% were male patients and 48% were female patients.
The researchers considered fungal growth in multiple media or a positive smear and growth on at least one medium to be a positive fungal culture.
Dr. Alfonso and colleagues identified 147 patients with nonbacterial infections in 2004 and 2005. Of those, 79 were contact lens users, 43 were noncontact lens wearers, and 25 did not have sufficient information to determine the status of their contact lens use.
“We wanted to first make sure our culture positive rate was the same it had been in the previous studies cited,” he said. “In 1986 our culture positive rate was 54.2%. In 2004 it was 47.9%, and in 2005 it was 47.4%. There was no statistical difference between these three.”
There was, however, an increase in nonbacterial culture-positive rates in contact lens wearers, he said. In 1986 the rate was 1.7%, and in 2004-05 it was 12.5%, he said.
The rate of fungal keratitis among contact lens wearers increased from 3.1% in 1986 to 19.6% in 2004-05, Dr. Alfonso said.
For more information:
- Eduardo C. Alfonso, MD, can be reached at Bascom Palmer Eye Institute, 900 NW 17th St., Miami, FL 33136; 305-326-6366; fax: 305-326-6337; e-mail: ealfonso@med.miami.edu.
- Daniele Cruz is an OSN Staff Writer who covers all aspects of ophthalmology, focusing on optics, refraction and contact lenses.