Living in an area with high levels of air pollution can increase your risk of developing macular degeneration and going BLIND, study warns

This is a typical rubbishy study of PM2.5 air pollution. It relies on the area a person lives in to describe anything about him/her. That quite different people might be living in the same area is not acounted for. We might, for instance, ask whrether or not it is mostly poor people who get AMD. No answer to that is available. All we are told is whether the sufferer lived in a poor area, which could mean many things. Their measure of pollution exposure was similarly inexact. They examined only whether a person lived in a polluted area. They had no estimate of how much pollution each person actually experienced.

There is however one thing unusual about this study. They found that many things -- such as living in a poor area -- DID affect the incidence of AMD but I can find no mention of the authors controlling for all such extraneous influences on the correlation between a polluted area and AMD incidence. We are thus left with the possible conclusion that it was other factors -- not pollution -- that increased levels of AMD. Poverty is one of the most common predictors of disease so we are quite at liberty to conclude from their report that it was poverty that caused poor eye function, not pollution. What a useless study!

Your risk of developing macular degeneration and going blind is increased by living in an area with a high level of air pollution, a study has warned.

Age-related macular degeneration (AMD) is a progressive form of vision loss that is the leading cause of blindness among UK adults aged 50 and over.

Known risk factors for AMD — alongside increasing age — include certain genetic factors and being a smoker.

Researchers from the UK studied data on 15,954 people — each of whom was aged 40–69 at the start of the study and initially reported no vision issues.

They monitored them for the development of AMD — and compared outcomes with the average level of air pollution where they lived.

They found that greater concentrations of air pollution were associated with up to an 8 per cent increase in the likelihood of developing macular degeneration.

Data for the study was collected by the UK Biobank, a large-scale database containing detailed genetic and health information on half-a-million participants.

Of the participants, 52,602 had their eyes examined and assessed for the structural changes in the thickness and numbers of receptors in the retina which are indicative of age-related macular degeneration.

The study used estimates of the average annual levels of air pollution at each subject's home address, considering pollutants such as fine particles (or PM2.5), nitrogen dioxide and nitrogen oxides which mainly come from vehicle exhausts.

The researchers found that just over 1 per cent of the study cohort — 1,286 people — ended up being diagnosed with age-related macular degeneration.

Once factors such as lifestyle and underlying health conditions were taken into account, the team found that participants exposed to higher concentrations of PM2.5 were 8 per cent more likely to develop AMD.

Exposure to PM2.5 and other pollutants was also found to be associated with changes in the structure of the subjects' retinas.

However, the team noted, 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 previous findings, they said, which have suggested that higher exposure to air pollution may make retinal cells more vulnerable and thereby increase one's 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.'

Molecular ophthalmologist Chris Inglehearn of the University of Leeds, who was not involved in the present study, said that the paper — and another from Taiwan — have both shown a link between air pollution and age-related macular degeneration.

While the studies have not proven that pollution is causing AMD, he said, 'the fact that these two independent studies reach similar conclusions gives greater confidence that the link they make is real.'

'These studies provide further evidence that links air pollution with detrimental impacts on human health,' he concluded.

'Age-related macular degeneration is the most common cause of sight loss in the developed world and so this finding is significant,' added Robert MacLaren, an ophthalmology expert from the University of Oxford.

'Participants in the study had an average age of around 60 and this small increase risk of 8 per cent is likely to be compounded further over ensuing decades.'

The full findings of the study were published in the British Journal of Ophthalmology.

The journal Abstract:

Association of ambient air pollution with age-related macular degeneration and retinal thickness in UK Biobank

By Uncle Tom Cobleigh and all


Aim: To examine the associations of air pollution with both self-reported age-related macular degeneration (AMD), and in vivo measures of retinal sublayer thicknesses.

Methods: We included 115 954 UK Biobank participants aged 40–69 years old in this cross-sectional study. Ambient air pollution measures included particulate matter, nitrogen dioxide (NO2) and nitrogen oxides (NOx). Participants with self-reported ocular conditions, high refractive error (< −6 or > +6 diopters) and poor spectral-domain optical coherence tomography (SD-OCT) image were excluded. Self-reported AMD was used to identify overt disease. SD-OCT imaging derived photoreceptor sublayer thickness and retinal pigment epithelium (RPE) layer thickness were used as structural biomarkers of AMD for 52 602 participants. We examined the associations of ambient air pollution with self-reported AMD and both photoreceptor sublayers and RPE layer thicknesses.

Results: After adjusting for covariates, people who were exposed to higher fine ambient particulate matter with an aerodynamic diameter <2.5 µm (PM2.5, per IQR increase) had higher odds of self-reported AMD (OR=1.08, p=0.036), thinner photoreceptor synaptic region (β=−0.16 µm, p=2.0 × 10−5), thicker photoreceptor inner segment layer (β=0.04 µm, p=0.001) and thinner RPE (β=−0.13 µm, p=0.002). Higher levels of PM2.5 absorbance and NO2 were associated with thicker photoreceptor inner and outer segment layers, and a thinner RPE layer. Higher levels of PM10 (PM with an aerodynamic diameter <10 µm) was associated with thicker photoreceptor outer segment and thinner RPE, while higher exposure to NOx was associated with thinner photoreceptor synaptic region.

Conclusion: Greater exposure to PM2.5 was associated with self-reported AMD, while PM2.5, PM2.5 absorbance, PM10, NO2 and NOx were all associated with differences in retinal layer thickness.

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