Recent outbreaks of atypical contact lens-related keratitis: what have we learned?

PURPOSE: To examine the public health implications of 2 recent outbreaks of atypical contact lens-related infectious keratitis.
DESIGN: Perspective based on the literature and authors' experience.
RESULTS: The contact lens-related Fusarium and Acanthamoeba keratitis outbreaks were each detected by dramatic rises seen in tertiary care centers in Singapore and the United States, respectively. Case-control studies of both outbreaks were able to identify a strong association with the use of different contact lens disinfection solutions. Their respective recalls resulted in a steep decline of Fusarium keratitis, but not of Acanthamoeba keratitis. Early investigations into each solution association implicated components not directly related to their primary disinfectant, but the true pathogenesis remains unknown. However, the number of Acanthamoeba cases individually attributed to each of almost all available disinfection systems exceeds the previously understood total United States incidence, suggesting other risk factors. Current standards do not require demonstration of anti-acanthamoebal activity. Yet, despite the inclusion of Fusarium in mandatory testing for solutions, current premarket testing was not predictive of the outbreak.
CONCLUSIONS: The 2 recent outbreaks of atypical contact lens-related keratitis have reinforced the value of tertiary care eye care centers in detecting early rises in rare infections and the power of adaptable, well-designed epidemiologic investigations. Although Fusarium keratitis has declined significantly with the recall of Renu with MoistureLoc (Bausch & Lomb Inc.), the persistence of Acanthamoeba keratitis demands fundamental changes in contact lens hygiene practices, inclusion of Acanthamoeba as a test organism, and contact lens disinfectant test regimens for all contact lens-related pathogens that are verifiably reflective of end user contact lens wear complications.