national outbreak of acanthamoeba keratitis associated with use of a contact lens solution united states an outbreak of acanthamoeba keratitis a rare potentially blinding corneal infection was detected in the united states in 2007 cases had been increasing since 2004 a casecontrol study was conducted to investigate the outbreak we interviewed 105 casepatients from 30 states and 184 controls matched geographically and by contact lens use available contact lenses cases solutions and corneal specimens from casepatients were cultured and tested by molecular methods in multivariate analyses casepatients had significantly greater odds of having used advanced medical optics complete moisture plus amocmp solution odds ratio 169 95 confidence interval 48595 amocmp manufacturing lot information was available for 22 casepatients but none of the lots were identical three unopened bottles of amocmp tested negative for acanthamoeba spp our findings suggest that the solution was not intrinsically contaminated and that its antiacanthamoeba efficacy was likely insufficient premarket standardized testing of contact lens solutions for activity against acanthamoeba spp is warranted