Abstract
SummaryBackgroundMany causes of vision impairment can be prevented or treated. With an ageing global population, the demands for eye health services are increasing. We estimated the prevalence and relative contribution of avoidable causes of blindness and vision impairment globally from 1990 to 2020. We aimed to compare the results with the World Health Assembly Global Action Plan (WHA GAP) target of a 25% global reduction from 2010 to 2019 in avoidable vision impairment, defined as cataract and undercorrected refractive error.MethodsWe did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. We fitted hierarchical models to estimate prevalence (with 95% uncertainty intervals [UIs]) of moderate and severe vision impairment (MSVI; presenting visual acuity from <6/18 to 3/60) and blindness (<3/60 or less than 10° visual field around central fixation) by cause, age, region, and year. Because of data sparsity at younger ages, our analysis focused on adults aged 50 years and older.FindingsGlobal crude prevalence of avoidable vision impairment and blindness in adults aged 50 years and older did not change between 2010 and 2019 (percentage change −0·2% [95% UI −1·5 to 1·0]; 2019 prevalence 9·58 cases per 1000 people [95% IU 8·51 to 10·8], 2010 prevalence 96·0 cases per 1000 people [86·0 to 107·0]). Age-standardised prevalence of avoidable blindness decreased by −15·4% [–16·8 to −14·3], while avoidable MSVI showed no change (0·5% [–0·8 to 1·6]). However, the number of cases increased for both avoidable blindness (10·8% [8·9 to 12·4]) and MSVI (31·5% [30·0 to 33·1]). The leading global causes of blindness in those aged 50 years and older in 2020 were cataract (15·2 million cases [9% IU 12·7–18·0]), followed by glaucoma (3·6 million cases [2·8–4·4]), undercorrected refractive error (2·3 million cases [1·8–2·8]), age-related macular degeneration (1·8 million cases [1·3–2·4]), and diabetic retinopathy (0·86 million cases [0·59–1·23]). Leading causes of MSVI were undercorrected refractive error (86·1 million cases [74·2–101·0]) and cataract (78·8 million cases [67·2–91·4]).InterpretationResults suggest eye care services contributed to the observed reduction of age-standardised rates of avoidable blindness but not of MSVI, and that the target in an ageing global population was not reached.FundingBrien Holden Vision Institute, Fondation Théa, The Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Foundation, Sightsavers International, and University of Heidelberg.
Highlights
With rising sociodemographic status and life expectancy, many countries around the world are seeing more people live into adulthood, increases in the average age of the population, and a shift in the disease burden towards non-communicable diseases and disabilities
We report global and regional estimates of the burden of moderate and severe vision impairment (MSVI) and blindness due to cataract, undercorrected refractive error, glaucoma, age-related macular degeneration, and diabetic retinopathy
We report a composite term of MSVI that comprises people meeting either moderate or severe visual acuity definitions
Summary
With rising sociodemographic status and life expectancy, many countries around the world are seeing more people live into adulthood, increases in the average age of the population, and a shift in the disease burden towards non-communicable diseases and disabilities. Most of the principal causes of vision impairment, including cataract and undercorrected refractive error,[1] are subject to this epidemiological transition[2] and carry significant indi vidual and societal costs.[3,4] Cataract surgery and the dispensing of spectacles are among the most costeffective health-care interventions currently available.[5,6,7] Addressing these reversible conditions by scaling up existing health-care systems to provide access to cataract surgery and spectacles is an important opportunity. It set a global target: to achieve by 2019 a 25% reduction from the baseline of 2010 in prevalence of “avoidable”[8] visual impairment, defined as the aggregated crude prevalence of cataract and underc orrected refractive error (presenting visual acuity
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