Atypical presentation of Acanthamoeba keratitis

Purpose. To present two cases of minimal pain Acanthamoeba keratitis to ale rt clinicians to remember Acanthamoeba when evaluating atypical cases of ke ratitis. Methods. The histories of two cases were reviewed with attention t o clinical presentation subjective complaints, treatment, and long-term out come. Results. In case 1, a 24-year-old man presented with decreased vision and an irritated feeling in his eye. He did not wear contact lenses. His i nitial diagnosis was adenoviral conjunctivitis. One month later, he was dia gnosed with atypical herpes simplex keratitis and started on acyclovir. Two weeks later, he was referred to the Cornea Service. Further history reveal ed the patient to be a professional triathlete who trained by swimming in a fresh water pond. He was found to have an unusually high pain tolerance. B iopsy revealed Acanthamoeba. He was admitted for intensive therapy with neo mycin, propamidine isethionate, and polyhexamethylene biguanide. Two years after diagnosis, he has best-corrected visual acuity of 20/100. In case 2, a 28-year-old man with known herpes simplex keratitis presented with decrea sed vision. He was started on topical trifluridine. After 6 weeks without i mprovement, he was referred for corneal evaluation. His eye always remained comfortable. Corneal sensation was markedly decreased. Further history rev ealed. that he swam in fresh water. Biopsy was positive for Acanthamoeba. A fter I year of therapy with polyhexamethylene biguanide and neomycin, visua l acuity was 20/200, and the patient underwent a corneal transplant. Conclu sion. Acanthamoeba keratitis must be considered in the differential diagnos is of keratitis, even without the classic presentation of severe pain and p redisposing corneal trauma, including contact lens wear.