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Air pollution link to heightened risk of age-related sight loss: study

By Emily Beament, PA Environment Correspondent

Exposure to air pollution could increase the risk of developing a form of irreversible sight loss, a large-scale study suggests.

Air pollutants, which are already known to cause a range of harmful health impacts on people, are linked to a heightened risk of age related macular degeneration (AMD), the long-term research shows.

AMD is a progressive form of sight loss which forms the leading cause of irreversible blindness in the over-50s in wealthy countries such as the UK, and known risk factors include older age, smoking and genetic factors.

The research, to examine if air pollution affects the condition drew on data from 115,954 participants of the large scale community-based UK Biobank study which involves more than half a million people.

All the participants were aged 40-69 at the start of the study and had no eye problems, and were asked to report any subsequent diagnosis of AMD by a doctor.

And 52,602 people whose eyes were examined with retinal imaging were assessed for structural changes in the thickness and numbers of receptors in the retina which are indicative of AMD.

The study also drew on estimates for pollutants including fine particles known as PM2.5, nitrogen dioxide and nitrogen oxides, which largely come from combustion in sources such as vehicle engines, to calculate average annual air pollution at people’s home addresses.

Just over 1% of the overall group, 1,286 people, were diagnosed with AMD, the study published in the British Journal of Ophthalmology found.

Analysis found that, once other factors such as lifestyle and underlying health conditions were taken into account, participants exposed to higher levels of concentrations of PM2.5 were 8% more likely to report they had been diagnosed with AMD.

PM2.5 and other pollutants were also associated with changes in the structure of people’s retinas.

The researchers said the study was an observational one, which did not intervene with people’s lives, and could not prove that pollution caused sight loss.

But it echoes findings elsewhere in the world, they said, and suggested higher exposure to air pollution may make the cells in the eye’s retina more vulnerable and increase the risk of AMD.

“Overall, our findings suggest that ambient air pollution, especially fine (particulate matter) or those of combustion-related particles, may affect AMD risk,” the researchers said.

“Our findings add to the growing evidence of the damaging effects of ambient air pollution, even in the setting of relative low exposure.”

Lead author of the study Professor Paul Foster, from University College London’s Institute of Ophthalmology, said: “Here we have identified yet another health risk posed by air pollution, strengthening the evidence that improving the air we breathe should be a key public health priority.

“Our findings suggest that living in an area with polluted air, particularly fine particulate matter or combustion-related particles that come from road traffic, could contribute to eye disease.

“Even relatively low exposure to air pollution appears to impact the risk of AMD, suggesting that air pollution is an important modifiable risk factor affecting risk of eye disease for a very large number of people.”

Commenting on the study, Chris Inglehearn, professor of molecular ophthalmology at the University of Leeds, said it and another from Taiwan both showed a link between air pollution and age-related macular degeneration.

While the links did not prove pollution was causing AMD, “the fact that these two independent studies reach similar conclusions gives greater confidence that the link they make is real”, he said.

“These studies provide further evidence that links air pollution with detrimental impacts on human health.”

Prof Robert MacLaren, professor of ophthalmology at the University of Oxford said: “Age-related macular degeneration is the most common cause of sight loss in the developed world and so this finding is significant.

“Furthermore, participants in the study had an average age of around 60 and this small increase risk of 8% is likely to be compounded further over ensuing decades.”

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