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March 2014, Issue 67

Global Burden of Disease Study: Prevalence and Causes of Blindness and Visual Impairment



Jost B. Jonas, MD
Department of Ophthalmology
Medical Faculty Mannheim
Heidelberg University
Mannheim, Germany

The recent Global Burden of Disease Study (GBD 2010) was a systematic scientific effort to quantify the comparative magnitude of various public health burdens in 187 countries from 1990 to 2010. The GBD 2010 included 291 diseases and injuries, 1,160 sequelae of these diseases and injuries, and 67 risk factors or clusters of risk factors. Funded by the Bill and Melinda Gates Foundation, the GBD 2010 was started in 2007. Summary papers were published in a dedicated triple issue of Lancet in December 2012.1-5 A landmark study in the field of epidemiology, the GBD 2010 reported a transition in the causes of death with a shift away from communicable, maternal, neonatal and nutritional causes to non-communicable diseases and injuries. This transition in the causes of death occurred parallel to a demographic transition including increased population size, increased average age in most regions, and decreased mortality rates. Correspondingly, there was an increase in the public health burdens associated with disability with a steady shift of disease causing increased disability and decreased mortality. There was a shift from risks related to poverty to risks related to lifestyle.1-3

The GBD 2010 provides information regarding the epidemiology of eye diseases including age-related macular degeneration. According to the GBD 2010, 32.4 million individuals worldwide were blind (defined as a presenting visual acuity <3/60) in 2010 and 191 million people had moderate or severe vision impairment (defined as a presenting visual acuity <6/18 but >3/60).6 The age-standardized prevalence of blindness in adults aged > 50 years showed profound differences according to geographic region. Prevalence of blindness was highest in Western Sub-Saharan Africa (6.0%), Eastern Sub-Saharan Africa (5.7%), South Asia (4.4%), and North Africa/Middle East (4.6%), and lowest in high income regions (such as USA, Canada, and Western Europe), with blindness prevalences less than 0.6% in high income regions.6 Similarly, the prevalence of moderate or severe vision impairment was highest in South Asia with 23.6% of the population aged >50 years affected, followed by Oceania (18.9%), Eastern and Western Sub-Saharan Africa and North Africa/Middle East (15.9%-16.8%). The prevalence of moderate or severe vision impairment was lowest (<5%) in the high income regions. After controlling for age, the prevalence of blindness was generally higher among women than among men in all world regions.

Comparing the years 1990 and 2010, the overall global age-standardized prevalences of blindness and visual impairment for adults aged >50 years decreased from 3.0% worldwide to 1.9%, and from 14.3% to 10.4%, respectively.6 Despite this decline in the prevalences of blindness and visual impairment, because of the increase in population and lifespan, the number of people who are blind has increased by 0.6 million, and the number of people with moderate or severe visual impairment has increased by 19 million in the last two decades.

The leading causes of blindness in 1990 and in 2010 were cataract and undercorrected refractive error, followed by age-related macular degeneration.7 Leading causes of visual impairment were undercorrected refractive error and cataract followed by age-related macular degeneration, with no change in the frequency-based ranking list from 1990 to 2010. There were large differences in the causes of blindness by region. In 2010, the proportion of blindness caused by cataract ranged from <15% in high income regions to over 40% in South and Southeast Asia and Oceania. The proportion of blindness caused by age-related macular degeneration was higher in regions with older populations: in the high income regions, Southern Latin America, and central and eastern Europe, more than 15% of blindness was caused by age-related macular degeneration. In contrast, 2.6% of blindness in South Asia was caused by macular degeneration. In the high income regions such as the United States, age-related macular degeneration was the leading cause of blindness in adults over 55 years of age.

In summary, the GBD 2010 demonstrates the significant public health burden of blindness and visual impairment. Worldwide, the leading causes of blindness and visual impairment are cataract, undercorrection of refractive error, and age-related macular degeneration.

References
1. Lim SS, Vos T, Flaxman AD, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012;380(9859):2224-60
2. Murray CJ, Vos T, Lozano R, et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 201;380:2197-223
3. Vos T, Flaxman AD, Naghavi M, et al. Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012;380:2163-96
4. Salomon JA, Vos T, Hogan DR, et al. Common values in assessing health outcomes from disease and injury: disability weights measurement study for the Global Burden of Disease Study 2010. Lancet 2012;380:2129-43
5. Lozano R, Naghavi M, Foreman K, et al. Global and regional mortality from 235 causes of death for 20 age groups in 1990 and 2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet. 2012 Dec 15;380(9859):2095-128. doi: 10.1016/S0140-6736(12)61728-0.
6. Stevens G, White R, Flaxman SR, et al. Global prevalence of visual impairment and blindness: magnitude and temporal trends, 1990-2010. Ophthalmology. 2013 Jul 10. doi:pii: S0161-6420(13)00480-6. 10.1016/j.ophtha.2013.05.025. [Epub ahead of print]
7. Bourne R, Stevens GA, White RA, et al. Causes of global visual loss: 1990-2010. The Global Burden of Disease Study. Lancet Global Health2013; http://dx.doi.org/10.1016/S2214-109X(13)70113-X

sponsor

Ingrid U. Scott, MD, MPH,  Editor

Professor of Ophthalmology and
Public Health Sciences,
Penn State College of Medicine

 

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