EyeWorld India March 2013 Issue

37 EWAP REFRACTIVE March 2013 ACS and the Cornea Society launch CorneaEd IKS is massive undertaking for ACS The Asia Cornea Society’s Infectious Keratitis Study (ACSIKS) is set to be a major game changer for the region. “Corneal blindness is big in Asia,” said Donald Tan, MD , Singapore, current president of the Cornea Society and the Asia Cornea Society (ACS). It’s a fair statement, summarizing the significance of the most important cause of blindness in the region second only to cataract, but it barely scratches the surface, given the full scope and many nuances of the problem. Most corneal disease in the world occurs in Asia, said Prof. Tan. Here, he said, corneal ulceration is a “silent epidemic.” But the challenge of corneal blindness in Asia isn’t confined to magnitude; unsurprisingly for the region, huge variations exist from country to country, such that the problem runs the gamut of the entire spectrum of corneal infections. Epidemiological patterns, for one, differ significantly, said Prashant Garg, MD , Hyderabad, India. For instance, whereas studies have identified contact lens use and ocular surface disease as the major risk factors for microbial keratitis in a developed region like Hong Kong, trauma is the most prevalent cause of infection in India, affecting a correspondingly different age group: Most patients in India, said Dr. Garg, fall in the range of 20-50 years—the economically productive age group. Wide variations also exist from country to country in terms of pathogen, environmental risk factors, the availability of drugs, antibiotic resistance patterns, access to treatment, and any number of other variables that have yet to be adequately quantified. To this end, the ACS has embarked on the ACSIKS, a multicenter, prospective observational study in 11 study centers in eight major locations (China, India, Japan, Korea, Philippines, Taiwan, Thailand, and Singapore). The study is intended to document the clinical management practices of doctors all over the region, while also collecting microbiological samples from recruited cases. To date, said Prof. Tan, the study has recruited 2,118 cases, with preliminary data analysis of 1,544 of these cases. Preliminary analysis, he said, has identified fungal and bacterial pathogens to be the main causes of infectious keratitis in the region. Editors’ note: ACSIKS is made possible by the support of Alcon (Fort Worth, Texas, USA/Hünenberg, Switzerland), Allergan (Irvine, Calif., USA), Bausch + Lomb (Rochester, NY, USA), and Santen (Napa, Calif., USA). The Asia Cornea Society (ACS) and Cornea Society have created an initiative to reach out to young ophthalmologists looking for opportunities to train in the cornea subspecialty. “CorneaEd is, quite simply, ‘cornea education,’” said Donald Tan, MD , Singapore, president of both societies, which, he said, have always had strong missions for education. The website is a joint educational initiative of the sister societies, essentially a registry with links to fellowship programs in the Asia-Pacific and the U.S. The idea, said Michael Belin, MD , vice president for international relations, Cornea Society, is to give young ophthalmologists the opportunity to find programs that will present them with experiences they might not otherwise have. This in mind, the two societies hope to select two young ophthalmologists in the corneal fellowship program of their choice. Applications will be available on the website in the first quarter of 2013. For more information and to access the registry, visit www.CorneaEd.org. the patient enough near vision. Therefore, with Presbyond Laser Blended Vision, we incorporated another natural visual process— filtering of spherical aberration—to increase the depth of field in each eye and achieve good binocular vision at all distances. In an eye with no spherical aberration, light is focused to a point, so any forward or backward movement of the object will make it instantly go out of focus. However, if we introduce some spherical aberration into the system, there is dissemination of the focal point, meaning that there is a wider range of distances where the focus is equivalent, although slightly reduced. This of course applies to the retinal image, but the image is still perceived as sharply as if there were no aberrations due to the natural ability of the visual cortex to “process” spherical aberration. This range is the depth of field and can be demonstrated by the better-than-expected distance vision in the near eye (the mean visual acuity is about 20/45 whereas 20/80 would be expected for a –1.50 D refraction). This concept is simply an extension of the eye’s natural state as everyone has some naturally occurring spherical aberration, and the brain is already preprogrammed to do this filtering. If there is too much spherical aberration, however, the visual cortex is no longer able to fully “process” the spherical aberration and will result in loss of contrast sensitivity and other aberration-related quality of vision symptoms, similar to those seen after multifocal ablations. The ideal depth of field in each eye is 3.00 D, but we have found that the maximum depth of field that can be safely induced is 1.50 D. Therefore, this spherical aberration method cannot be used to correct presbyopia by itself but can be combined with monovision to improve the range of vision in each eye. The increased depth of field in each eye enables good near vision to be achieved with a lower degree of anisometropia than in traditional monovision, which we refer to as micromonovision. With Presbyond Laser Blended Vision, it is possible to displace the foci between the eyes and create continuous vision, from near to intermediate to far. In essence, this strategy creates a blend zone of vision between the two eyes at intermediate distances meaning that much less suppression is required and there is no dissociation between the eyes. In fact, patients even retain a functional level of uncorrected stereoacuity—proving that they have binocular function. In Presbyond Laser Blended Vision, a number of factors are considered including age, accommodative amplitude, pre-op wavefront, tolerance to anisometropia, and the amount of refractive error. The software then combines these factors to generate an ablation profile with the aim of leaving the patient with an appropriate level of spherical aberration in order to maximize the depth of field without compromising contrast sensitivity, stereoacuity, or night vision. At one year after Presbyond Laser Blended Vision, binocular UDVA was 20/20 or better and UNVA was J2 or better in 95% of 136 myopic patients ( ≤ –8.50 D), 77% of 111 hyperopic patients ( ≤ +5.75 D), and 95% of 148 emmetropic patients (within ±0.88 D). The safety in terms of contrast sensitivity was the same as for continued on page 43