AUG 2014

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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59 EW INTERNATIONAL Risk factors and causes of infectious keratitis vary by region and demographics I n Asia, infectious keratitis is a significant cause of corneal morbidity and blindness. "Most corneal disease in the world occurs in Asia," said Donald T.H. Tan, FRCS, Singapore National Eye Centre, Singapore. "Here, corneal ulceration is a silent epidemic." A preliminary analysis in one of the largest studies of its kind to date, the Asia Cornea Society Infectious Keratitis Study (ACSIKS), identified fungal and bacterial pathogens to be the main causes of infectious keratitis in the region. Why focus this study in Asia? "There is a vast spectrum of in- fectious organisms in Asia," said Dr. Tan, ACSIKS principal investigator and current president of the Cornea Society and the Asia Cornea Society. "There are emerging new threats on infection in this part of the world." ACSIKS intends to develop im- proved strategies for prevention and treatment, with the ultimate goal of reducing ocular morbidity and Infectious keratitis: The Asian scenario by Matt Young and Gloria D. Gamat EyeWorld Contributing Writers August 2014 I nfectious keratitis is a significant cause of vision loss around the world, but it is especially prevalent in Asia. While fungal keratitis is relatively uncommon in North America, it comprises almost half the cases diagnosed in the Far East. Variation in the risk factors and causative organisms is not surprising, but it is now more fully under- stood as the result of a large epidemiologic study. In this article, EyeWorld features the preliminary findings of the landmark Asia Cornea Society study of infectious keratitis as presented by Donald T.H. Tan, FRCS, and Prashant Garg, MD. A better under- standing of the problem is the first step to finding a solution for this regional epidemic. John A. Vukich, MD international editor corneal blindness related to infectious keratitis in Asia. Risk factors Since commencing in April 2012, the study recruited 6,569 cases of infectious keratitis from 12 study centers in 8 major Asian countries (India, China, Thailand, Japan, Korea, Taiwan, Philippines, and Singapore). From these participants, 2,657 isolates have been archived. Reporting results of the phase 1 study at the recent Cornea Day in Boston, Dr. Tan stated that local risk factors vary with region and demo- graphics. Specifically, a significant variation in risk factors can be seen when data from developing coun- tries (India, China, Philippines, and Thailand) are compared to the results in the more developed countries (Singapore, Taiwan, Japan, and Korea). "Corneal trauma is the main risk factor for developing coun- tries," he said. "But in developed East Asian countries, it is clear that contact lens wear is the important risk factor." Phase 1 data further showed that overall, trauma was the risk factor occurring with greatest frequency (52.7%), followed by contact lens wear in 17.7% of cases. Other risk factors identified for infectious keratitis were prior ocular surgery (9.5%), ocular surface dis- ease (6.2%), topical steroids (3.1%), bullous keratopathy (1.5%), tradi- tional medical treatments (0.8%), and other causes (8.4%). Phase 2 study Based on the 2,657 isolates archived, investigators identified the infec- tious keratitis-related organisms. The results showed the causes to be 46% fungi, 20% gram-positive bacteria, and 15% gram-negative bacteria. While fungi and bacteria topped the infection-causing organisms, the data showed wide variations when broken down by country. "For example, India, China, and Philippines have more fungi cases, while Singapore and Japan have more bacteria," Dr. Tan said. As ACSIKS is entering into phase 2, further study of fungal and bacte- rial isolates will be incorporated. Identify infection-causing organisms As a co-investigator in ACSIKS, Prashant Garg, MD, LV Prasad Eye Institute, Hyderabad, India, who has been working on nontuberculous mycobacterium causing infectious keratitis, enumerated the challenges that these organisms pose to physi- cians. A challenge is difficulty in diagnosis as this is a relatively rare organism and requires acid-fast staining for microscopic identifi- cation. Fortunately, most atypical mycobacteria grow easily on blood or chocolate agar. The medical management is also challenging. "Drugs that are highly effective against these organisms are not available for ophthalmic use and need to be administered in much higher doses; the duration of treat- ment is usually longer and that re- sults in drug toxicity," Dr. Garg said. "Further, several patients would not respond to medical management despite being administered adequate therapy." Nontuberculous mycobacterium is just one example. As the ACSIKS delves into phase 2, better under- standing of these infection-causing organisms will enable doctors in Asia to adjust their clinical manage- ment practices in treating infectious keratitis. "Fungal and bacterial infections remain the main causes of infectious keratitis. More knowledge regarding risk factors, organisms, and anti- microbial resistance patterns is needed," Dr. Tan said. EW Editors' note: The Asia Cornea Society Infectious Keratitis Study (ACSIKS), a supranational, 3-year, multicenter study on infectious keratitis involving 12 clinical sites from major ophthalmic institutions in 8 Asian countries, was conducted under the auspices of the Asia Cornea Society and made possible by the support of Alcon (Fort Worth, Texas), Allergan (Irvine, Calif.), Bausch + Lomb (Bridgewater, N.J.), Santen (Napa, Calif.), and Orbis International (New York). Contact information Garg: prashant@lvpei.org Tan: donald.tan.t.h@snec.com.sg International outlook Infectious keratitis Source: Neil Sher, MD

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