• An irritated left eye followed by a geographic epithelial corneal defect developed in a 42-year-old man. Disciform edema developed in the cornea, and the lesion progressed to a ring-shaped abscess. The lesion failed to respond to medical therapy. After two penetrating keratoplasties, histopathologic examination and electron microscopic studies established the diagnosis of Acanthamoeba keratitis. Subsequent cultures and immunofluorescent studies identified the organism as Acanthamoeba castellani. Following treatment with antibiotics and corneal cryotherapy, there has been no evidence of recurrence. Morphologically and immunologically identical amebae were also cultured from the patient's hot tub and surrounding garden.