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.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of population-based prevalence surveys
PubMed 33275949 · doi:10.1016/S2214-109X(20)30489-7
What was done
A systematic review and meta-analysis of population-based eye disease surveys published between January 1980 and October 2018. Hierarchical models were used to estimate prevalence and 30-year trends (1990–2020) of moderate and severe vision impairment (MSVI; visual acuity <6/18 to 3/60) and blindness (<3/60 or visual field <10°) by cause, age, region, and year. The analysis focused on adults aged 50 years and older due to data sparsity at younger ages, assessing progress toward the World Health Assembly target of a 25% reduction in avoidable vision impairment (cataract and undercorrected refractive error) between 2010 and 2019.
What was found
Crude prevalence of avoidable vision impairment and blindness in adults aged 50 and older was essentially unchanged between 2010 and 2019 (percentage change -0.2% [95% UI -1.5 to 1.0]; 2019 prevalence 9.58 cases per 1,000 [95% UI 8.51 to 10.8]; 2010 prevalence 96.0 cases per 1,000 [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]). Total cases grew for both avoidable blindness (10.8% [8.9 to 12.4]) and MSVI (31.5% [30.0 to 33.1]). In 2020, the leading causes of blindness in this age group were cataract (15.2 million cases) and glaucoma (3.6 million); leading causes of MSVI were undercorrected refractive error (86.1 million cases) and cataract (78.8 million cases).
Why it matters
The global target of a 25% reduction in avoidable vision impairment was not met. Although age-standardised avoidable blindness rates decreased, population growth and ageing increased the absolute number of people affected by avoidable blindness and vision impairment.
Limits
The study was restricted to adults aged 50 years and older due to sparse data in younger groups. The abstract does not disclose the exact number of included surveys or participants, and global estimates rely on hierarchical statistical modeling to interpolate data for regions with limited direct surveillance.
Cited by
- supports Glaucoma is the second leading cause of blindness worldwide after cataracts.
- supports Cataracts are the most common cause of blindness.
- contradicts Macular degeneration is the largest cause of blindness besides glaucoma.