People With Blindness From Cataract Are Poorer Than Those With Normal Sight

Blindness affects about 45 million people worldwide, and more than a third is caused by cataract. Although cataract can be treated with an inexpensive, simple operation, some evidence suggests that lack of money is a major barrier to uptake of cataract surgery by individuals in poor countries.

In the new study, Hannah Kuper (International Centre for Eye Health, London School of Hygiene and Tropical Medicine) and colleagues identified 596 people aged 50 y or more with severe cataract-induced visual impairment, mainly through a survey of the population in these three countries. They matched each case to a normally sighted person (a "control") of similar age and sex living nearby. Poverty was measured through monthly per capita expenditure (PCE), as well as self-rated wealth and ownership of assets.

In all three countries, cases were more likely than controls to be in the lowest quarter (quartile) of the range of PCEs for that country. In the Philippines, for example, people with cataract-induced visual impairment were three times more likely than controls to have a PCE in the lowest quartile than in the highest quartile.

The risk of cataract-related visual impairment increased as PCE decreased in all three countries. Similarly, severe cataract-induced visual impairment was more common in those who owned fewer assets and those with lower self-rated wealth. However, there was no consistent association between PCE and the level of cataract-induced visual impairment.

"This study confirms an association between poverty and blindness," say the authors, "and highlights the need for increased provision of cataract surgery to poor people, particularly since cataract surgery is a highly cost-effective intervention in these settings."

In an expert commentary on the study, Susan Lewallen (Kilimanjaro Centre for Community Ophthalmology, Moshi, Tanzania), who was uninvolved in the research, says it is useful to "unravel the complex web of poverty and blindness."

There are many factors involved, says Lewallen, in whether an individual's cataract blindness is cured, of which the economic status of the household is only one. "Focusing too narrowly on the monetary costs (direct or indirect) of cataract surgery may lead us to miss other critical social determinants that keep people blind."