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Cataracts remain leading cause of blindness W orldwide blindness decreased between 1990 and 2010, according to a study published in the December 2013 issue of The Lancet G lobal Health. 1 Although the number of blind people globally remained the same in 2010 compared with 1990—close to 32 million—the percentage of people blind from a preventable or treatable cause decreased from 68% to 65%, said lead study investigator Rupert R.A. Bourne, MD, Vision a nd Eye Research Unit, Postgraduate Medical Institute, Anglia Ruskin University, Cambridge, U.K. That 3% change is significant because of the worldwide aging population, Dr. Bourne said. "With an aging and more eld- erly global population, one would have anticipated that the numbers would have increased significantly during this period," Dr. Bourne said. "The absolute numbers mask an impressive decline in the percentage of the population that is blind—the age-standardized prevalence for all ages has declined in all regions and globally from 0.6% to 0.47% in 2010." The decline may be due to a decline in poverty levels, improved public health measures, and eye health service development, Dr. Bourne said. "The latter appears most likely when considering the burden of cataract, uncorrected refractive error, and trachoma, in which marked reductions in age- standardized prevalence were ob- served between 1990 and 2010," he said. Investigating the stats The study is the first comprehensive review of all blindness and vision impairment data since 1980 and includes the review of 2.9 million vision exams from 243 studies. Dr. Bourne and co-investigators are part of the Vision Loss Expert Group, a worldwide collaboration of 79 ophthalmologists and optometrists who joined together in 2007 for the Global Burden of Disease study. The data review published in November in The Lancet Global H ealth included published and un- published data on causes of blind- ness, defined as a visual acuity of less than 3/60 in the better eye and moderate and severe vision impair- ment of less than 6/18 but at least 3/60 in the better eye. Investigators estimated the proportions of visual impairment caused by cataract, g laucoma, macular degeneration, diabetic retinopathy, trachoma, and uncorrected refractive error and analyzed results according to age, geographical region, and year. Although other studies have analyzed blindness, such studies usually focus on a certain region of the world or a specific ethnic group, t he study reported. Investigators divided the regions of the world into 21 areas, and they identified at least two studies for 18 of the 21 regions. However, they did not find studies with cause-specific data for central Africa or eastern Europe. They only found one study for central Europe. Tracking the results The study investigators found that in both 1990 and 2010, the leading causes of blindness were cataract, uncorrected refractive error, and macular degeneration. There was a large difference in blindness according to world region. Blindness from cataracts ranged from less than 15% in the world's high-income regions to 40% or more in southeast Asia and Oceania. Blindness from macular degenera- tion was higher in more affluent regions with older populations, including southern Latin America and central and western Europe. The proportion of macular degeneration blindness in these regions was 15% or more; in contrast, it was a lower range of 2% to 6% in south Asia. Blindness from glaucoma was lowest in south Asia, east and west sub-Saharan Africa, and Oceania—all around 4%—while the highest value was in tropical Latin America, where the proportion was 15.5%. Investigators did not identify any trachoma-related blindness in 13 of the 21 regions, although the disease affected 3.6% of those blind in west sub-Saharan Africa and 8.1% in east sub-Saharan Africa. Moderate to severe vision im- pairment was most often caused by uncorrected refractive error, cataract, by Vanessa Caceres EyeWorld Contributing Writer Blindness decreases over 20-year time span 18-47 News_EW March 2014-DL2 copy_Layout 1 3/6/14 2:46 PM Page 26