Prevalence and causes of vision loss in North Africa and Middle East in 2015: magnitude, temporal trends and projections

Authors: Kahloun R, Khairallah M, Resnikoff S, Cicinelli MV, Flaxman SR, Das A, Jonas JB, Keeffe JE, Kempen JH, Leasher J, Limburg H, Naidoo K, Pesudovs K, Silvester AJ, Tahhan N, Taylor HR, Wong TY, Bourne RRA; Vision Loss Expert Group of the Global Burden of Disease Study.

Geographical coverage: North Africa and Middle East

Sector: Burden of Disease

Sub-sector: Prevalence

Equity focus: Not reported

Study population: People with vision loss

Review type: Effectiveness review

Quantitative synthesis method: Not applicable (hierarchical Bayesian logistic regression)

Qualitative synthesis method: Not applicable

Background

Over the past two decades the age-standardised prevalence of blindness and vision impairment in North Africa and the Middle East (NAME) has fallen, yet regional conflict, displacement and socioeconomic instability continue to challenge public health. Conversely, countries with greater stability have implemented action plans aligned with global initiatives such as VISION 2020. Robust estimates of the burden and its causes are essential for planning and prioritising eye-health services in the region.

Objective

To estimate the prevalence and causes of blindness and vision impairment in North Africa and the Middle East from 1990 to 2015 and to project trends to 2020.

Main findings

• Declining prevalence but growing numbers – Between 1990 and 2015 the age-standardised prevalence of blindness fell from 1.72 % to 0.95 %, and moderate-to-severe vision impairment (MSVI) from 6.66 % to 4.62 %. Population growth and ageing nevertheless increased the absolute numbers affected to an estimated 3.47 million blind and 18.26 million with MSVI in 2015, with further rises projected by 2020.
• Leading causes – Cataract and uncorrected refractive error were the principal causes of blindness in 2015; uncorrected refractive error remained the chief cause of MSVI, followed by cataract.
• Changing aetiological profile – From 1990 to 2015 the proportion of vision loss attributable to cataract, corneal opacity and trachoma declined, whereas shares due to uncorrected refractive error, glaucoma, age-related macular degeneration and diabetic retinopathy rose and were expected to keep increasing to 2020.
• Sex and country differentials – Vision impairment was consistently more common in women, particularly those aged ≥ 50 years. Prevalence varied markedly between countries, with Afghanistan and Yemen highest and the United Arab Emirates lowest, reflecting disparities in health infrastructure, socioeconomic status and political stability.

Methodology

Data were drawn from a Global Burden of Disease–related systematic review of population-based studies (1980 – July 2014) plus unpublished sources identified by the Vision Loss Expert Group. Hierarchical Bayesian logistic regression produced age- and sex-specific prevalence estimates of blindness (presenting visual acuity < 3/60 in the better eye) and MSVI (3/60 ≤ VA < 6/18) for 1990, 2015 and 2020. United Nations demographic forecasts underpinned projections, and cause-specific proportions were modelled geographically and temporally. Results were expressed as posterior means with 80 % uncertainty intervals; analyses followed PRISMA standards.

Applicability / external validity

Marked heterogeneity across the countries—owing to differences in population size, economic development and data availability—limits direct generalisability to every setting. Variations in disease definitions and potential under-reporting of certain causes may also affect comparability.

Geographic focus

North Africa and the Middle East.

Summary of quality assessment

Overall confidence in the review’s conclusions is low. Although inclusion criteria and time frame were clear and sophisticated Bayesian methods applied, the review did not report screening, data-extraction or quality-appraisal procedures.