Acanthamoeba keratitis (AK) is a rare and debilitating eye infection that can result in permanent visual impairment or blindness. CDC has been monitoring AK infections since a 2007 AK outbreak investigation that resulted in a recall of a contact lens solution.

As a response to reports of elevated numbers and unusual clusters of AK infections, CDC and other federal, state, and local public health partners started an investigation in March 2011. The purpose of this investigation was to identify common risk factors for AK that could be modified to prevent new AK infections from occurring.

CDC staff, state health officials, and local health officials conducted standardized telephone interviews of 167 people with AK from 36 states and Puerto Rico, their treating ophthalmologists, and their primary eye care providers. Additionally, 163 contact lens users 12 years of age and older who have never had AK were also interviewed to better understand why some people get AK and others do not.

The interviews were finished in June, 2011.  The AK Investigation Team is working to analyze all of the information collected.  Preliminary analyses identified an association with wearing contact lenses and contact lens hygiene practices but did not reveal the need to recall any particular contact lens-associated products.  At this time, CDC has communicated these findings to regulatory agencies (e.g., FDA). Additional analyses are being done to explore whether other activities or products might be associated with a higher risk of infection.  Based on those findings, public health and clinical professionals may take action to prevent new infections and improve the health of those with current infections. Contact lens wearers can reduce their risk for AK by practicing appropriate contact lens hygiene.