Here's how air pollution is linked to increased risk of irreversible vision loss

Air pollution is associated with an increased risk of progressive and irreversible sight loss, known as age related macular degeneration (AMD), according to a long-term study that could pave the way for new treatment options for the disorder.

The researchers, including those from the University College London, UK, noted that AMD is the leading cause of irreversible blindness among the over 50s in high-income countries, with the numbers of those affected projected to reach 300 million by 2040.

Known risk factors include older age, smoking, and genetic make-up, they said.

Given that ambient air pollution is associated with heightened risks of heart and respiratory diseases, the study, published in the British Journal of Ophthalmology, analysed if it might also be associated with a heightened risk of AMD.

The researchers drew on data from 115,954 UK Biobank (UKBB) study participants aged 40-69 with no eye problems at the start of this study in 2006.

Measures of ambient air pollution included those for particulate matter (PM2.5), nitrogen dioxide (NO2), and nitrogen oxides (NOx).

Of the total number of study participants, 1,286 were diagnosed with AMD, according to the researchers.

Among the 52,602 people whose eyes had been assessed, 75 per cent of those with a clinical diagnosis of AMD had signs of AMD on retinal imaging compared to only 12 per cent of those without a clinical diagnosis of AMD, they said.

Analysis of the data showed that higher fine particulate matter (PM2.5 ) exposure was associated with a higher (8 per cent) risk of AMD, while all other pollutants, except coarse particulate matter, were associated with changes in retinal structure.

The researchers noted that it is an observational study, and as such, can't establish cause., adding the findings, however, echo those found elsewhere in the world.

They suggest ambient air pollution could plausibly be associated with AMD through oxidative stress or inflammation.

"Overall, our findings suggest that ambient air pollution, especially fine particulate matter or those of combustion-related particles, may affect AMD risk," the researchers noted.