Abstract

Contemporary data for causes of vision impairment and blindness form an important basis of recommendations in public health policies. Refreshment of the Global Vision Database with recently published data sources permitted modelling of cause of vision loss data from 1990 to 2015, further disaggregation by cause, and forecasts to 2020. In this systematic review and meta-analysis, we analysed published and unpublished population-based data for the causes of vision impairment and blindness from 1980 to 2014. We identified population-based studies published before July 8, 2014, by searching online databases with no language restrictions (MEDLINE from Jan 1, 1946, and Embase from Jan 1, 1974, and the WHO Library Database). We fitted a series of regression models to estimate the proportion of moderate or severe vision impairment (defined as presenting visual acuity of <6/18 but ≥3/60 in the better eye) and blindness (presenting visual acuity of <3/60 in the better eye) by cause, age, region, and year. We identified 288 studies of 3 983 541 participants contributing data from 98 countries. Among the global population with moderate or severe vision impairment in 2015 (216·6 million [80% uncertainty interval 98·5 million to 359·1 million]), the leading causes were uncorrected refractive error (116·3 million [49·4 million to 202·1 million]), cataract (52·6 million [18·2 million to 109·6 million]), age-related macular degeneration (8·4 million [0·9 million to 29·5 million]), glaucoma (4·0 million [0·6 million to 13·3 million]), and diabetic retinopathy (2·6 million [0·2 million to 9·9 million]). Among the global population who were blind in 2015 (36·0 million [12·9 million to 65·4 million]), the leading causes were cataract (12·6 million [3·4 million to 28·7 million]), uncorrected refractive error (7·4 million [2·4 million to 14·8 million]), and glaucoma (2·9 million [0·4 million to 9·9 million]). By 2020, among the global population with moderate or severe vision impairment (237·1 million [101·5 million to 399·0 million]), the number of people affected by uncorrected refractive error is anticipated to rise to 127·7 million (51·0 million to 225·3 million), by cataract to 57·1 million (17·9 million to 124·1 million), by age-related macular degeneration to 8·8 million (0·8 million to 32·1 million), by glaucoma to 4·5 million (0·5 million to 15·4 million), and by diabetic retinopathy to 3·2 million (0·2 million to 12·9 million). By 2020, among the global population who are blind (38·5 million [13·2 million to 70·9 million]), the number of patients blind because of cataract is anticipated to rise to 13·4 million (3·3 million to 31·6 million), because of uncorrected refractive error to 8·0 million (2·5 million to 16·3 million), and because of glaucoma to 3·2 million (0·4 million to 11·0 million). Cataract and uncorrected refractive error combined contributed to 55% of blindness and 77% of vision impairment in adults aged 50 years and older in 2015. World regions varied markedly in the causes of blindness and vision impairment in this age group, with a low prevalence of cataract (<22% for blindness and 14·1-15·9% for vision impairment) and a high prevalence of age-related macular degeneration (>14% of blindness) as causes in the high-income subregions. Blindness and vision impairment at all ages in 2015 due to diabetic retinopathy (odds ratio 2·52 [1·48-3·73]) and cataract (1·21 [1·17-1·25]) were more common among women than among men, whereas blindness and vision impairment due to glaucoma (0·71 [0·57-0·86]) and corneal opacity (0·54 [0·43-0·66]) were more common among men than among women, with no sex difference related to age-related macular degeneration (0·91 [0·70-1·14]). The number of people affected by the common causes of vision loss has increased substantially as the population increases and ages. Preventable vision loss due to cataract (reversible with surgery) and refractive error (reversible with spectacle correction) continue to cause most cases of blindness and moderate or severe vision impairment in adults aged 50 years and older. A large scale-up of eye care provision to cope with the increasing numbers is needed to address avoidable vision loss. Brien Holden Vision Institute.

Highlights

  • Contemporary and accurate data for the cause-specific prevalence of vision impairment and blindness are a fundamental basis of public health policies, such as allocation of resources and health service planning, and are important for prioritisation of scientific advances and industry research

  • The Vision Loss Expert Group reported estimates of vision impairment resulting from a systematic review of published literature and available unpublished data from population-based studies of the prevalence of blindness and vision impairment dating from 1980 to 2015,1 using a continuously updated database of population-based studies

  • A decrease occurred in the age-standardised prevalence of blindness and moderate or severe vision impairment between 1990 and 2015 (the global age-standardised all-age prevalence of blindness decreased from 0·75% [80% uncertainty interval (80% UI) 0·25–1·41] in 1990 to 0·48% [0·17–0·87] in 2015), and the global age-standardised all-age prevalence of moderate or severe vision impairment decreased from burden and 55% of the blindness burden in adults aged 50 years and older, both of which are completely treatable causes

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Summary

Introduction

Contemporary and accurate data for the cause-specific prevalence of vision impairment and blindness are a fundamental basis of public health policies, such as allocation of resources and health service planning, and are important for prioritisation of scientific advances and industry research. Age-related macular degeneration, corneal opacity, diabetic retinopathy, and trachoma were less frequent causes of blindness and vision impairment than were cataract and uncorrected refractive error, some of which are preventable. Crude global prevalence (all ages) of blindness and vision impairment of each cause decreased markedly between 1990 and 2015, except for diabetic retinopathy, which increased. The number of people affected by blindness and vision impairment is increasing, which is attributable to population growth and ageing. The predicted increase in the number of people with avoidable vision impairment (defined as vision impairment that could be either treated or prevented by known, cost-effective means) to 2020 is mainly driven by south Asia and east Asia

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