Global estimates on the number of people blind or visually impaired by glaucoma: A meta-analysis from 2000 to 2020

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

Geographical coverage: Southeast Asia, East Asia, Central Asia, Oceania, Central Europe, Eastern Europe, Latin America, the Caribbean, North Africa, the Middle East, South Asia, Sub-Saharan Africa

Sector: Burden of disease

Sub–sector: Prevalence

Equity focus: Not reported

Study population: People with glaucoma

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background

Glaucoma is a leading cause of irreversible blindness, and its burden is projected to increase as the global population ages. Primary open‑angle glaucoma (POAG) is the most common form, with risk factors that include older age, genetic susceptibility and raised intra‑ocular pressure (IOP). Whereas previous projections estimated rising prevalence, the impact of glaucoma encompasses rates of vision loss as well. This meta‑analysis updates global estimates of glaucoma‑related blindness and vision impairment over the past two decades, taking regional and sex‑based differences into account.

Objectives

To estimate global and regional trends from 2000 to 2020 in the number of people visually impaired by glaucoma and their share of the total population with vision impairment.

Main findings

In 2020 glaucoma caused blindness in 3.61 million people (8.39 % of all blindness) and moderate or severe vision impairment (MSVI) in 4.14 million people (1.41 % of all MSVI). High‑income regions had the largest proportion of glaucoma‑related blindness (26.12 %), whereas Sub‑Saharan Africa recorded the highest age‑standardised prevalence (0.66 %). Between 2000 and 2020 the global age‑standardised prevalence of glaucoma‑related blindness fell by 26.06 % in males and 21.75 % in females, while MSVI rose by 3.7 % and 7.3 % respectively. Pronounced reductions were observed in Southeast Asia, East Asia and Oceania; smaller declines occurred in Sub‑Saharan Africa and Latin America. Glaucoma thus remains a leading cause of irreversible blindness worldwide, highlighting the need for earlier detection and equitable access to treatment, particularly in low‑ and middle‑income countries.

Methodology

Population‑based studies reporting visual acuity that could be mapped to the Snellen scale were eligible. A systematic search of published literature and grey sources from 1 January 1980 to 1 October 2018 identified 137 studies; data were extracted from 117. These were combined with results from Rapid Assessment of Avoidable Blindness (RAAB) surveys, the US National Health and Nutrition Examination Survey, and the World Health Organization (WHO) Study on Global Ageing and Adult Health. Prevalence data were entered into a mixed‑effects meta‑regression model for distance vision impairment and blindness by cause. Estimates were produced by age, sex, year and location, then age‑standardised using the GBD standard population.

Applicability / external validity

The use of a large, global dataset supports broad applicability; however, gaps persist for some countries and for distinguishing glaucoma subtypes. Local variations in disease detection, treatment access and data quality may limit direct transferability.

Geographic focus

Included studies spanned Southeast Asia, East Asia, Central Asia, Oceania, Central Europe, Eastern Europe, Latin America, the Caribbean, North Africa, the Middle East, South Asia and Sub‑Saharan Africa.

Summary of quality assessment

Overall we attributed low confidence because of methodological shortcomings: duplicate screening and data extraction were not clearly reported, no formal risk‑of‑bias assessment was undertaken, and a list of excluded studies was not provided. Potential publication bias was not examined. These limitations introduce uncertainty and reduce the certainty of the pooled estimates.