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74 EW CORNEA March 2012 Increasing awareness of Acanthamoeba by Vanessa Caceres EyeWorld Contributing Editor ary care eye hospital" in the Septem- ber 2010 issue of Cornea. Drs. Colby and Tanhehco investigated the number of Acanthamoeba cases at the Massachusetts Eye and Ear Infir- mary between 2000 and 2008 and found an increase in its incidence. Another study published in the same issue of Cornea tracked Acanthamoeba keratitis at the Cole A patient with Acanthamoeba keratitis Source: Anna S. Kitzmann, M.D. Two recent reports outline incidence, treatment challenges I f you're treating a corneal ulcer as bacterial in nature and it's not getting better, consider Acanthamoeba keratitis, recom- mends Kathryn Colby, M.D., Cornea Service, Massachusetts Eye and Ear Infirmary, and ophthalmol- ogy department, Harvard Medical School, Boston. Although Acanthamoeba keratitis is not that common, its incidence has increased in recent years, and aiming for an early diagnosis can help prevent more serious problems, Dr. Colby said. "It's very important to consider these atypical agents when seeing a patient," she said. Dr. Colby and co-investigator Tasha Tanhehco, M.D., published the article "The clinical experience of Acanthamoeba keratitis at a terti- Eye Institute, Cleveland, between 1999 and 2008. Although study in- vestigators did not find an increase in the number of cases seen each year, they did conclude that early and intense treatment can best help outcomes in these patients, said study co-investigator Bennie H. Jeng, M.D., associate professor of clinical ophthalmology; co-director, University of California San Fran- cisco Cornea Service; and chief, ophthalmology department, San Francisco General Hospital. Here's a summary of what the two studies found, followed by some practical implications. The Massachusetts study Dr. Colby's study retrospectively re- viewed Acanthamoeba cases that had a positive culture from a corneal specimen, clinical evidence of Acan- thamoeba, and follow-up data for more than 6 months. Only four cases were found between 2000 and 2003—for some of those years, there were no identified cases, Dr. Colby said. However, 26 cases were identi- fied between January 2004 and December 2008. Eleven cases did not have sufficient follow-up infor- mation, so investigators only re- viewed the remaining 15 cases. The average patient age in the Are you a fan of EyeWorld? Like us on Facebook at Find us on social media facebook.com/EyeWorldMagazine positive cases was 40.9 years, and most patients were males. The cases were twice as likely to present in the fall and winter than other seasons. Almost all patients had been referred to the Cornea Service from another eyecare provider. "The most com- mon misdiagnoses at initial presen- tation were viral (4 cases), fungal (3 cases), bacterial (1 case), and un- known (3 cases)," the investigators wrote. Three patients (4 eyes) had been accurately diagnosed upon ini- tial presentation. The best corrected visual acuity (BCVA) at initial pres- entation was 20/400 or less in 7 of 15 cases. Investigators tracked common risk factors. "Possible risk factors for these cases included soft contact lens wear (12 of 15 cases), exposure to freshwater or saltwater sources (8 of 15 cases), chronic ocular surface disease (6 of 15 cases), ocular trauma (3 of 15 cases), and concomitant infectious keratitis (2 of 15 cases)," investigators wrote. They defined exposure to water sources as rinsing or storing contacts in tap water or swimming or bathing while wearing contacts. Three patients had used Complete MoisturePlus Multi- Purpose Solution (Advanced Medical Optics, AMO, Santa Ana, Calif.), which was associated with a nation- wide Acanthamoeba outbreak and voluntarily recalled in May 2007. The most common treatment was hourly topical anti-amoebic agents, topical broad-spectrum antibiotics, and commonly, an oral antifungal agent. However, penetrat- ing keratoplasty (PK) was necessary in 8 of 15 eyes, including six of the cases that had an initial BCVA of less than 20/400. "Of the 8 eyes that had corneal transplants, the final BCVA was im- proved in 5 cases and worse in 3 cases compared with the BCVA at initial presentation. However, only 3 of 8 cases achieved a final BCVA better than 20/200," investigators wrote. In the 15 total cases, final BCVA ranged from 20/20 to hand motions. The number of Acanthamoeba cases peaked in 2006 and then slightly decreased, investigators wrote. This may be due to the recall of MoisturePlus and an increased awareness of Acanthamoeba among eyecare providers along with better patient education since the recall, they added. Cole Eye Institute cases The study at Cole Eye Institute was also retrospective and identified 29 eyes of 26 patients who had either culture- or tissue-proven Acanthamoeba keratitis. A diagnosis was made based on one or more of the following factors: positive cul- ture on corneal scraping, cysts or trophozoites identified on biopsy specimens, positive confocal mi- croscopy, or characteristic clinical presentation with complete response continued on page 76