The purpose of this systematic review was to estimate worldwide the number of people with moderate and severe visual impairment (MSVI; presenting visual acuity <6/18, ≥3/60) or blindness (presenting visual acuity <3/60) due to uncorrected refractive error (URE), to estimate trends in prevalence from 1990 to 2010, and to analyze regional differences. The review focuses on uncorrected refractive error which is now the most common cause of avoidable visual impairment globally.
The systematic review of 14,908 relevant manuscripts from 1990 to 2010 using Medline, Embase, and WHOLIS yielded 243 high-quality, population-based cross-sectional studies which informed a meta-analysis of trends by region. The results showed that in 2010, 6.8 million (95% confidence interval [CI]: 4.7–8.8 million) people were blind (7.9% increase from 1990) and 101.2 million (95% CI: 87.88–125.5 million) vision impaired due to URE (15% increase since 1990), while the global population increased by 30% (1990–2010). The all-age age-standardized prevalence of URE blindness decreased 33% from 0.2% (95% CI: 0.1–0.2%) in 1990 to 0.1% (95% CI: 0.1–0.1%) in 2010, whereas the prevalence of URE MSVI decreased 25% from 2.1% (95% CI: 1.6–2.4%) in 1990 to 1.5% (95% CI: 1.3–1.9%) in 2010. In 2010, URE contributed 20.9% (95% CI: 15.2–25.9%) of all blindness and 52.9% (95% CI: 47.2–57.3%) of all MSVI worldwide. The contribution of URE to all MSVI ranged from 44.2 to 48.1% in all regions except in South Asia which was at 65.4% (95% CI: 62–72%).
We conclude that in 2010, uncorrected refractive error continues as the leading cause of vision impairment and the second leading cause of blindness worldwide, affecting a total of 108 million people or 1 in 90 persons.
African Vision Research Institute, University of KwaZulu-Natal, South Africa (KSN); Brien Holden Vision Institute, Sydney, Australia (KSN, SR); School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia (KSN, SR); Nova Southeastern University, Ft. Lauderdale, Florida (JL); Vision & Eye Research Unit, Anglia Ruskin University, Cambridge, United Kingdom (RRB, HP); School of Computer Science & Heinz College, Carnegie Mellon University, Pittsburgh, Pennsylvania (SRF); Department of Ophthalmology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany (JBJ); L. V. Prasad Eye Institute, Hyderabad, India (JK); Health Information Services, Grootebroek, Netherlands (HL); NHMRC Centre for Clinical Eye Research, Flinders University, Adelaide, South Australia, Australia (KP); Department of Genes and Environment, Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway (RAW); Singapore Eye Research Institute, Singapore (TYW); and Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia (HRT).
aA list of the Vision Loss Expert Group members appears at http://www.anglia.ac.uk/ruskin/en/home/microsites/veru/other_research_areas/global_burden_of_diseases.html.
Kovin S. Naidoo African Vision Research Institute 172 Umbilo Road, Durban 4000 South Africa e-mail: firstname.lastname@example.org