Keratitis, an inflammation of the cornea, is a potentially blinding infection and is one of the most severe complications associated with contact lens use. However, outbreaks of fungal keratitis are rare in contact lens wearers. Since March 1, 2005, Singapore has seen a sharp increase in the number of keratitis cases caused by the Fusarium fungus species. Recent reports have also confirmed that 122 patients in the U.S. and 33 in Hong Kong have developed Fusarium keratitis, suggesting that this outbreak may be part of a global problem for contact lens wearers, according to information in the article.
Wei-Boon Khor, M.B.B.S., of the Singapore Eye Research Institute, and colleagues examined the Fusarium keratitis outbreak in Singapore. All cases of fungal keratitis among contact lens wearers from March 2005 through May 2006 were included in the study. Researchers collected corneal samples and patients' contact lenses, lens cases and current bottle of contact lens solution for testing. Telephone interviews were also conducted.
During the 15-month period, 66 contact lens wearers (68 affected eyes) were diagnosed with Fusarium keratitis. From this, the researchers estimated that the annual national incidence of Fusarium keratitis was 2.35 cases for every 10,000 contact lens wearers in Singapore. Nearly all patients wore soft, disposable contact lenses (98.5 percent) and a high proportion (93.9 percent) reported using ReNu brand cleaning solution, including 42 patients (63.6 percent) who reported using ReNu with MoistureLoc. Most patients (81.8 percent) had poor lens hygiene habits, including wearing daily contacts overnight, wearing expired lenses and wearing contacts while swimming. The authors suggest that these habits, however, cannot fully account for the outbreak. Two-thirds of patients (n = 44) had severe, sight-threatening lesions requiring an average first-visit hospital stay of 6.5 days, and five patients required corneal transplantation.
"We believe that Singapore is facing a new and unprecedented outbreak of Fusarium keratitis and that this is the first time that such an outbreak has been reported among contact lens wearers anywhere in the world," the authors write. "A national case-control study currently under way will shed further light on the probable risk factors for this outbreak, including the role of contact lens solutions." The authors conclude by encouraging physicians and clinicians to "maintain a high index of suspicion for fungal infection when evaluating and treating patients with contact lens-associated microbial keratitis."
(JAMA. 2006; 295: 2867 – 2873. Available pre-embargo to media at www.jamamedia.org.)
Editor's Note: The funding and administrative support for this study was provided by the Singapore Eye Research Institute.
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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