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

Author: GBD 2019 Blindness and Vision Impairment Collaborators; Vision Loss Expert Group of the Global Burden of Disease Study.

Geographical coverage: Central Sub-Saharan Africa, Central Asia, and Eastern Europe

Sector: Burden of Disease

Sub-sector: Prevalence

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background

Global initiatives like VISION 2020 and the WHO’s eye health action plan have emphasised the importance of updated data on vision impairment. Vision loss continues to be a major public health concern, affecting quality of life, economic potential, and mortality, especially among older adults. Age-related conditions such as cataract, macular degeneration, glaucoma, and diabetic retinopathy are increasingly common due to global ageing and epidemiological transitions. The Vision Loss Expert Group’s Global Vision Database provides crucial epidemiological insights. In this analysis, the earlier estimates from 2015 have been refined with more recent and detailed data, highlighting the need to address both distance vision loss and uncorrected presbyopia.

Objective

To extensively update estimates of the global vision loss burden, presenting estimates for 2020, temporal change over three decades between 1990 and 2020, and forecasts for 2050.

Main findings

The findings revealed that in 2020, an estimated 43.3 million (95% uncertainty interval [UI]: 37.6 to 48.4) people were blind, with 55% (23.9 million, 95% UI: 20.8 to 26.8) being female. An estimated 295 (267 to 325) million had moderate or severe vision impairment, of whom 163 million (55%; 147–179) were female; 258 (233 to 285) million had mild vision impairment, of whom 142 million (55%; 128–157) were female; and 510 million (371–667) had visual impairment from uncorrected presbyopia, of whom 280 million (55%; 205–365) were female. The highest burden was observed in South Asia, followed by East and Southeast Asia, with older adults (50+ years) accounting for the majority of cases.

Between 1990 and 2020, the global age-standardised prevalence of blindness among older adults decreased by 28.5% (95% UI: –29.4 to –27.7), with the decrease being larger among males (–33.2%, –34.0 to –32.3) than among females (–25.0%, –26.0 to –23.9). However, moderate or severe vision impairment increased slightly by 2.5% (1.9 to 3.2), and a more substantial increase was seen among females (4.27%, 1.86 to 3.17) than among males (0.35%, –0.31 to 1.03). Notably, during this period, the number of people who were blind increased by 50.6% (47.8 to 53.4) and the number of people with moderate or severe vision impairment increased by 91.7% (87.6 to 95.8).

By 2050, it is projected that 61 million people will be blind, 474 million will have moderate or severe vision impairment, 360 million will have mild vision impairment, and 866 million will be affected by uncorrected presbyopia. These increases are expected to be driven primarily by demographic shifts, including longer life expectancy and the ageing of populations in both high-income and low- and middle-income countries.

Regional and sex disparities were notable throughout the analysis. Sub-Saharan Africa and South Asia exhibited the highest age-standardised prevalence rates of blindness in older adults. Additionally, females aged 50 years and older consistently exhibited higher prevalence rates across all severity levels of vision impairment, with the greatest difference observed in uncorrected presbyopia.

Methodology

The searches were conducted in Embase, SciELO, MEDLINE, the WHO Library Database, and OpenGrey, alongside additional grey literature sources to identify relevant studies published between 1 January 1980 and 1 October 2018. Studies were included if they assessed visual acuity using a test chart that could be mapped to the Snellen scale and included a sample representative of the general population. Presenting vision loss (measured with the participant’s existing corrective lenses) and best-corrected vision loss (measured after correction with lenses or a pinhole) were also included, but self-reported vision loss was excluded.

The articles were screened against the eligibility criteria. The relevant data were extracted and combined with data from Rapid Assessment of Avoidable Blindness (RAAB) surveys, which sampled individuals aged 50–99 years in low-income and middle-income settings. Hierarchical models were fitted to estimate the 2020 prevalence of mild, moderate, and severe vision impairment, as well as blindness and uncorrected presbyopia, with 95% uncertainty intervals. The analysis also forecasted vision impairment trends up to 2050 using age-specific prevalence rates and population projections.

Applicability/external validity

The review did not explicitly discuss the applicability or external validity of its findings; however, it highlighted sparse data in regions such as Central Sub-Saharan Africa, Central Asia, and Eastern Europe, which required extrapolation from other areas.

Geographic focus

The authors did not apply any geographical limits. The study included data from multiple regions worldwide, including Andean Latin America, Australasia, the Caribbean, Central Asia, Central Europe, Central Latin America, Central Sub-Saharan Africa, East Asia, Eastern Europe, Eastern Sub-Saharan Africa, high-income Asia Pacific, high-income North America, North Africa and the Middle East, Oceania, South Asia, Southeast Asia, Southern Latin America, Southern Sub-Saharan Africa, Tropical Latin America, Western Europe, and Western Sub-Saharan Africa.

Summary of quality assessment

Confidence in the review conclusions is low. Searches covered multiple databases and surveys, with clear inclusion/exclusion criteria and transparent reporting. Hierarchical models estimated the 2020 prevalence of various types of vision impairment and projected trends to 2050. However, the review did not assess study quality, provide lists of included or excluded studies, specify reviewer numbers, mention language restrictions, or report checking reference lists or contacting study authors.