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Clinical Characteristics of Acanthamoeba Keratitis Infections in 28 States, 2008 to 2011

Ross, Jonathan MD; Roy, Sharon L. MD, MPH; Mathers, William D. MD; Ritterband, David C. MD; Yoder, Jonathan S. MPH; Ayers, Tracy MS; Shah, Rupa D. MD; Samper, Monika E. RN; Shih, Carolyn Y. MD, MBA; Schmitz, Ann DVM, AM; Brown, Allison C. PHD, MPH

doi: 10.1097/ICO.0000000000000014
Clinical Science

Purpose: The aim was to describe a geographically and clinically diverse sample of cases of Acanthamoeba keratitis (AK) and establish the risk factors for poor outcomes among patients with this disease.

Methods: We conducted a retrospective, population-based case series of 116 patients with AK identified through a national surveillance network. Data were collected via a medical record review by diagnosing ophthalmologists and by phone interviews with patients. Exact logistic regression modeling was used to determine risk factors for poor visual outcomes.

Results: Among patients with data available on contact lens use, it was found that 93.3% wore contact lenses. The median time from symptom onset to care seeking was 2 days, whereas the median time from symptom onset to diagnosis was 27 days. Keratoplasty was performed in 27 of 81 patients with available outcome data and was more likely in patients >40 years old [odds ratio (OR) 5.25, 95% confidence interval (CI) 1.49–21.92]. When adjusted for age, the risk factors for keratoplasty included the presence of a ring infiltrate (OR 40.00, 95% CI 3.58–447.0) or any sign of stromal invasion (OR 10.48, 95% CI 2.56–55.09). One-third of patients with available data on best-corrected visual acuity had a best-corrected visual acuity <20/200, with the presence of a ring infiltrate as the only significant predictor of this outcome when adjusted for age (aOR 3.45, 95% CI 1.01–12.31).

Conclusions: AK remains challenging to diagnose. Consequently, patients with advanced disease are more likely to have poor outcomes, particularly if they are older. The increasing awareness of AK among general eye care providers may shorten referral times and potentially improve outcomes.

Supplemental Digital Content is Available in the Text.

*Division of Foodborne, Waterborne and Environmental Disease, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA;

Casey Eye Institute, Oregon Health and Science University, Portland, OR;

Department of Ophthalmology, New York Eye and Ear Infirmary, New York, NY;

§Department of Ophthalmology, Case Western Reserve University, Cleveland, OH;

Acute and Communicable Disease Prevention Section, Oregon Public Health Division, Portland, OR;

Department of Ophthalmology, North Shore University Hospital, Great Neck, NY; and

**Bureau of Epidemiology, Florida Department of Health, Tallahassee, FL.

Reprints: Jonathan Ross, Centers for Disease Control and Prevention, 3300 Netherland Avenue #5B, Bronx, NY 10463 (e-mail:

J. Ross conducted work on this project with support from a fellowship funded by a grant from Pfizer, Inc. D. C. Ritterband has worked as a consultant for Bausch and Lomb. The other authors have no funding or conflicts of interest to disclose.

Note: The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

Received June 25, 2013

Accepted September 18, 2013

Copyright © 2014 Wolters Kluwer Health, Inc. All rights reserved.