Acanthamoeba keratitis: Epidemiology, detection and treatment results of a large series

Purpose: To evaluate patients with keratitis for Acanthamoeba using confocal microscopy. Methods: We examined over 300 patients with epitheliopathy and keratitis using tandem scanning confocal microscopy. We identified 99 patients with confocal evidence of acanthamoeba and confirmed the diagnosis with epithelial scrape biopsy and histologic examination. Eight patients had bilateral disease. Results: The most frequent risk factors included contact lens use 39%, exposure to contaminated water 17% Ten patients used hard or RGP lenses, only 5 wore EWSCL. Twenty-three patients had no identifiable risk factors. The most common presenting symptoms were pain 40%, redness 63%, blurred vision 48% and photophobia 50%. The most common preliminary diagnosis was herpes simplex keratitis, 31 patients. Nine patients required corneal transplantation during their course of treatment. Three of these had residual organisms in the corneal button. Most patients were treated with chlorhexidine 0.02%, brolene, or PHMB 0.02%. Treatment was based on the number of organisms seen with confocal microscopy and the number of orgarisms appeared to respond to the intensity of treatment. Almost all patients showed improvement with this therapy. Conclusion: Acanthamoeba appears to be an opportunistic organism which may be frequently overlooked but which can readily be identified with confocal microscopy and epithelial biopsy and histologic examination.