The prevalence of cataracts is lowest and macular degeneration is greatest in the highest-income regions, according to the largest ever analysis of worldwide vision impairment and blindness data. The study also found that more women have vision impairment as a result of cataract and macular degeneration than men.
The study, published in The Lancet Global Health journal, was led by Professor Rupert Bourne of the Vision and Eye Research Unit at Anglia Ruskin University. It examined the main causes of blindness and vision impairment worldwide and by geographical region, including analysis of trends over time.
The study used a vast range of published and unpublished data on vision impairment and blindness to produce figures for 1990 and 2010. Professor Bourne said the results will help inform the setting of priorities, development of policies, and for planning. “Additionally, our data will be a useful tool to help mobilise eye-care services from governments, donors and civil society,” he said.
Decreasing Impact of Cataracts
The number of people affected by blindness caused by cataracts decreased between 1990 and 2010 from 12.3 million to 10.8 million, and for moderate and severe vision impairment (MSVI) it fell from 44 million to 35.2 million
In 2010, the proportion of blindness caused by cataracts ranged from less than 15 per cent in high-income regions, to more than 40 per cent in south and southeast Asia, and Oceania.
Macular Degeneration Hits High Income Groups
The proportion of blindness caused by macular degeneration (the loss of central vision) was higher in regions with older, higher-income populations, such as Europe and North America. In these areas more than 15 per cent of blindness was caused by macular degeneration, whereas the proportion was much lower in regions such as south Asia (2.6 per cent).
In all regions, the proportion of blindness and MSVI caused by cataract and macular degeneration was higher in women than in men.
Cataract or uncorrected refractive error, both easily treatable, led to 54 per cent of blindness cases and 71 per cent of MSVI cases in 2010. Of the 31.8 million people who were blind in 1990, 68 per cent had preventable or treatable causes. By 2010, the proportion had decreased to 65 per cent of the 32.4 million who were blind.
Consistent Results
Julie Heraghty, chief executive officer of the Macular Disease Foundation Australia said the results from the study are consistent with other research, which shows macular degeneration remains the major cause of major vision loss and legal blindness in the developed world.
“While cataracts remain the main cause of blindness globally, cataracts are now a much less common cause of blindness in the developed world due to the greater affordability and accessibility of cataract surgery,” said Ms. Heraghty.
“The slightly higher rates of macular degeneration in women are also consistent with large population based studies including the Blue Mountains Eye Study.
“Moreover as women tend to live somewhat longer than men, it is not surprising that more cases of macular degeneration are seen in women.
“Several of these points are discussed in the report from a recent Ageing and Low Vision Summit, held in Barcelona, which was co-organised by the Macular Disease Foundation Australia,” added Ms. Heraghty.
The study was funded by the Bill & Melinda Gates Foundation, Fight for Sight, the Fred Hollows Foundation, and the Brien Holden Vision Institute.
