[Painless acanthamoeba keratitis].

A 37-year-old contact lens wearer was treated for herpes simplex keratitis. After an initial improvement the keratitis became much worse. An annular infiltrate gave rise to the suspicion of acanthamoeba keratitis even though the patient was not in pain. This diagnosis was confirmed by histological and microbiological examination of the corneal disc after keratoplasty. Acanthamoeba keratitis should be considered even in the absence of pain, especially when the patients are contact lens wearers.