Prevalence and Causes of Vision Loss in East Asia: 2015: Magnitude, Temporal Trends, and Projections

Author: Cheng CY, Wang N, Wong TY, Congdon N, He M, Wang YX, Braithwaite T, Casson RJ, Cicinelli MV, Das A, Flaxman SR, Jonas JB, Keeffe JE, Kempen JH, Leasher J, Limburg H, Naidoo K, Pesudovs K, Resnikoff S, Silvester AJ, Tahhan N, Taylor HR, Bourne RRA; Vision Loss Expert Group of the Global Burden of Disease Study.

Geographical coverage: China and Taiwan

Sector: Burden of Disease

Sub-sector: Epidemiology

Equity focus: Not reported

Study population: Patients with cataract

Review type: Effectiveness review

Quantitative synthesis method: Meta-analysis

Qualitative synthesis method: Not applicable

Background

East Asia, home to nearly one-fifth of the global population, is experiencing rapid growth in its elderly demographic, with a projected 22% increase every five years from 2015 onward. This demographic shift is contributing to a rise in age-related eye diseases and vision impairment. Vision loss ranks among the top three causes of years lived with disability (YLD), significantly affecting mobility, independence, and quality of life. In 2010, an estimated 33.3 million people in East Asia had moderate to severe vision impairment (MSVI) and 5.2 million were blind. The major causes identified were cataract (28.1%) and uncorrected refractive error (13.7%). In light of ongoing socio-economic changes and new data, an updated assessment of the burden and causes of vision loss is essential for public health planning and resource allocation.

Objective

To update the epidemiological data by analysing the prevalence and causes of vision loss in East Asia for 2015, provide projections for 2020, and compare these findings globally.

Main findings

A total of 44 studies met the inclusion criteria for the Global Burden of Disease Study super-region of East Asia. Seventeen studies were conducted in both rural and urban settings, 13 in urban areas only, and 14 in rural areas only.

In 2015, East Asia had an estimated 6.19 million blind individuals, 52.88 million with MSVI, and 265.34 million with uncorrected presbyopia. The age-standardised prevalence was 0.37% for blindness, 3.06% for MSVI, and 32.91% for uncorrected presbyopia. Women were generally more affected (2.74%) than men (2.56%), and this burden was projected to rise by 2020. Specifically, blindness was expected to increase to 6.70 million and MSVI to 58.48 million cases by 2020.

Cataract and uncorrected refractive error were the leading causes of vision loss. In 2015, cataract accounted for 43.6% of blindness and uncorrected refractive error for 12.9%. Other causes included glaucoma (7.1%), age-related macular degeneration (5.3%), corneal diseases (4.3%), and diabetic retinopathy (0.5%). For MSVI, uncorrected refractive error was the primary cause (47.1%), followed by cataract (32.5%), with smaller contributions from AMD, glaucoma, and others.

From 1990 to 2015, the burden of vision impairment due to uncorrected refractive error, cataract, glaucoma, and diabetic retinopathy increased. In contrast, vision loss from trachoma and corneal diseases declined, particularly due to effective public health measures in China.

The study highlighted the need for public health interventions to improve access to cataract surgery, raise awareness about refractive error correction, and implement screening programmes for glaucoma and diabetic retinopathy.

Methodology

The review included population-based studies published between 1980 and 2014. Prevalence estimates were based on presenting visual acuity thresholds: blindness (<3/60 in the better eye), MSVI (3/60 to <6/18), mild vision impairment (6/18 to <6/12), and uncorrected presbyopia. Search terms were drawn from previous GBD-related systematic reviews. A hierarchical Bayesian model meta-analysis was used to estimate prevalence and causes of vision loss specific to East Asia. Detailed methods were reported elsewhere.

Applicability/external validity

The review included only studies from China and Taiwan, excluding Japan and South Korea, which may limit regional generalisability. Differences in diagnostic criteria, use of rapid assessment methods focusing mainly on cataract and refractive error, and a high number of cases grouped under “other causes” reduced the precision of cause-specific estimates. Caution is advised when extrapolating the findings across the broader East Asian population.

Geographic focus

The review focused on East Asia but included only studies from China and Taiwan.

Summary of quality assessment

Overall, there is low confidence in the conclusions. The review clearly defined inclusion criteria and spanned a wide timeframe (1980–2014). It employed robust Bayesian hierarchical models and stratified results by age, sex, and geography. However, it lacked details regarding study screening, data extraction, and quality appraisal processes.