EyeWorld Asia-Pacific June 2014 Issue

64 EWAP NEWS & OPINION June 2014 Blindness decreases over 20-year time span by Vanessa Caceres EyeWorld Contributing Writer 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 Global 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 and 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 elderly 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 observed 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 The data review published in November in The Lancet Global Health included published and unpublished data on causes of blindness, defined as a visual acuity of less than 3/60 in the better eye and moderate and severe vision impairment of less than 6/18 but at least 3/60 in the better eye. Investigators estimated the proportions of visual impairment caused by cataract, glaucoma, 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, the 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 degeneration 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 impairment was most often caused by uncorrected refractive error, cataract, and macular degeneration. Impairment from an uncorrected refractive error was especially high in south Asia. Women were more likely to be affected by blindness and moderate to severe vision impairment worldwide. “Worldwide, cataract caused 35.5% of blindness in women, compared with 30.1% in men, and for moderate to severe visual impairment, the values were 20.2% and 15.9%, respectively,” the investigators wrote. They also found macular degeneration was more common in women than men. The age-standardized prevalence of trachoma, cataract, and uncorrected refractive error between 1990 and 2010 around the world decreased. A similar prevalence for glaucoma, macular degeneration, and diabetic retinopathy decreased for blindness but increased slightly for visual impairment. Examining implications The investigators noted that about half of the decline in blindness and moderate to severe visual impairment was due to a decline in cataracts. Proportions also declined due to decreases in uncorrected refractive error. A reduction in corneal scarring from trachoma contributed to some of the decline, particularly in the east sub-Saharan Africa region. The investigators’ results are an extension of work done for VISION 2020: the Right to Sight, a global action plan to eliminate blindness from preventable causes. “The research is a reinforcement for professionals, non-governmental organizations, and governments that we are working correctly,” said Anna Rius, MPH , UNESCO chair for Visual Health and Development, Department of Optometry and Optics, Universitat Politècnica de Catalunya, Barcelona. Ms. Rius has continued on page 66