Trends in prevalence of blindness and distance and near vision impairment over 30 years: an analysis for the Global Burden of Disease Study

Abstract

Summary Background To contribute to the WHO initiative, VISION 2020: The Right to Sight, an assessment of global vision impairment in 2020 and temporal change is needed. We aimed to extensively update estimates of global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990–2020, and forecasts for 2050. Methods We did a systematic review and meta-analysis of population-based surveys of eye disease from January, 1980, to October, 2018. Only studies with samples representative of the population and with clearly defined visual acuity testing protocols were included. We fitted hierarchical models to estimate 2020 prevalence (with 95% uncertainty intervals [UIs]) of mild vision impairment (presenting visual acuity ≥6/18 and <6/12), moderate and severe vision impairment (<6/18 to 3/60), and blindness (<3/60 or less than 10° visual field around central fixation); and vision impairment from uncorrected presbyopia (presenting near vision <N6 or <N8 at 40 cm where best-corrected distance visual acuity is ≥6/12). We forecast estimates of vision loss up to 2050. Findings In 2020, an estimated 43·3 million (95% UI 37·6–48·4) people were blind, of whom 23·9 million (55%; 20·8–26·8) were estimated to be female. We estimated 295 million (267–325) people to have moderate and severe vision impairment, of whom 163 million (55%; 147–179) were female; 258 million (233–285) to have mild vision impairment, of whom 142 million (55%; 128–157) were female; and 510 million (371–667) to have visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205–365) were female. Globally, between 1990 and 2020, among adults aged 50 years or older, age-standardised prevalence of blindness decreased by 28·5% (–29·4 to −27·7) and prevalence of mild vision impairment decreased slightly (–0·3%, −0·8 to −0·2), whereas prevalence of moderate and severe vision impairment increased slightly (2·5%, 1·9 to 3·2; insufficient data were available to calculate this statistic for vision impairment from uncorrected presbyopia). In this period, the number of people who were blind increased by 50·6% (47·8 to 53·4) and the number with moderate and severe vision impairment increased by 91·7% (87·6 to 95·8). By 2050, we predict 61·0 million (52·9 to 69·3) people will be blind, 474 million (428 to 518) will have moderate and severe vision impairment, 360 million (322 to 400) will have mild vision impairment, and 866 million (629 to 1150) will have uncorrected presbyopia. Interpretation Age-adjusted prevalence of blindness has reduced over the past three decades, yet due to population growth, progress is not keeping pace with needs. We face enormous challenges in avoiding vision impairment as the global population grows and ages. Funding Brien Holden Vision Institute, Fondation Thea, Fred Hollows Foundation, Bill & Melinda Gates Foundation, Lions Clubs International Founda...

Causes of blindness and vision impairment in 2020 and trends over 30 years, and prevalence of avoidable blindness in relation to VISION 2020: the Right to Sight: an analysis for the Global Burden of Disease Study

“…230 (61%) of these 376 data sources were RAABs. 16 Many studies incorporated in the 2017 update 1 have since submitted more granular levels of disaggregated data, enabling more precise estimates of the causes of global vision impairment in 2020 and their temporal changes. Data sources for blindness and MSVI caused by myopic macular degeneration were sparse globally with the majority of sources from China.…”

“…We then looked at the contribution of individual causes to global visual impairment in 2020. Among the global 33·6 million adults aged 50 years and older who were blind in 2020 16 the leading causes of blindness ( table 2 ) were cataract (15·2 million cases [95% UI 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 (0·9 million cases [0·6–1·2]). For the estimated 206 million aged 50 years and older adults with MSVI in 2020, 16 the leading causes of MSVI ( table 3 ) were undercorrected refractive error (86·1 million cases [74·2–101·0]), followed by cataract (78·8 million cases [67·2–91·4]), age-related macular degeneration (6·2 million cases [5·0–7·6]), glaucoma (4·1 million cases [3·2–5·2]), and diabetic retinopathy (2·9 million cases [2·1–3·9]).…”

“…The separation of raw data into datasets, including total all-cause moderate vision impairment, severe vision impairment, and blindness, has been explained in detail elsewhere, in addition to a full list of the data sources. 16 Cause-specific analyses are described below.…”

“…Data collected using RAAB methodology were adjusted to comprehensive surveys (reference definition) using the same adjustment factors as for all-cause MSVI and blindness (described in a sister paper on all-cause vision loss). 16 This approach was used because there were many more data available for all-cause moderate vision impairment, severe vision impairment, and blindness than for each specific cause, allowing for more data-rich models.…”

“…We produced location, year, age, and sex-specific estimates of MSVI and blindness using Disease Modelling Meta-Regression (Dismod-MR) 2.1, which is described in detail elsewhere. 16 , 17 , 18 Global estimates are first produced with a mixed effects non-linear model using all available data to produce a global model fit as well as fixed and random effects. These outputs are passed to the GBD super-region level (seven super-regions) as a prior, and super-region fits are generated using super-region input data and the global prior.…”