Worldwide causes of blindness mapped

Major geographical differences exist worldwide in cases of cataracts and macular degeneration, according to the largest-ever analysis of worldwide vision impairment and blindness, which was recently published in The Lancet Global Health journal.

Researchers of this study, led by Dr Rupert Bourne, BSc (Hons), FRCOphth, MD, of the Vision and Eye Research Unit at Anglia Ruskin University, Cambridge, UK, analysed a large range of both published and unpublished data on vision impairment and blindness to produce figures for 1990 and 2010 of the main causes of blindness and vision impairment worldwide and by geographical region.

Some of the important findings of this study, funded by the Bill & Melinda Gates Foundation, Fight for Sight, the Fred Hollows Foundation and the Brien Holden Vision Institute, include the following:

• The number of people affected by blindness caused by cataracts decreased between 1990 and 2010, from 12.3 million to 10.8 million.
• The number of people affected by moderate and severe vision impairment fell from 44 million to 35.2 million.
• The causes of blindness differed substantially by region, with the prevalence of cataracts being lowest and macular degeneration being greatest in the highest-income regions.
• In 2010, the proportion of blindness caused by cataracts ranged from 40% in South and Southeast Asia and Oceania.
• The proportion of blindness caused by macular degeneration was higher in regions with older, higher-income populations including Europe and North America. In these areas, > 15% of blindness was caused by macular degeneration, with the proportion much lower in regions such as South Asia (2.6%).
• In all regions, the proportion of blindness and moderate and severe vision impairment caused by cataract and macular degeneration was higher in women than in men.
• In 2010, cataract or uncorrected refractive error led to 54% of blindness cases and 71% of moderate and severe vision impairment cases.
• Of the 31.8 million people who were blind in 1990, 68% had preventable or treatable causes. By 2010, this proportion had decreased to 65% of the 32.4 million who were blind.

"Being able to study in detail the changes in cause-specific prevalence of blindness and vision impairment is important for the setting of priorities, development of policies and for planning," said Dr Bourne. "Additionally, our data will be a useful tool to help mobilize eye care services from governments, donors and civil society," he concluded.

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