The findings, published in the RANZCO Journal of Clinical and Experimental Ophthalmology, suggest obstructive sleep apnoea (OSA) could be a modifiable risk factor associated with the 'wet' form of late-stage age-related macular degeneration (AMD).
University of Melbourne Master's student Attiqa Chaudhary along with members of the CERA's Macular Research unit, led by Professor Robyn Guymer AM, conducted the study. They also worked with sleep disorder expert Professor Matthew Naughton from Monash University to analyse the results.
The team conducted a sleep study involving 225 participants aged over 50 with different stages of AMD and measured their oxygen levels over three nights with a home-based finger oximeter. Their level of OSA was calculated based on the oxygen levels in their blood overnight.
The results showed that moderate-to-severe OSA, which results in lower levels of oxygen in the blood overnight, was associated with an increased risk of having wet AMD compared to those without OSA.
Study co-supervisor Dr Carla Abbott says the findings are something clinicians should be aware of.
"Like AMD, sleep apnoea mainly affects people over the age of 50 and many people don't realise they have it," Dr Abbott says.
"If this association is validated it may well be worth asking people with high-risk early stages of AMD if they have any symptoms suggestive of OSA, as treating OSA might reduce the risk of developing wet AMD."
Nocturnal hypoxia and wet AMD
Nocturnal hypoxia often occurs as a result of OSA, where a person's airway becomes blocked or narrowed overnight, reducing their oxygen intake.
A lack of oxygen overnight can cause various health issues over time, but the light-sensitive retina in the eye may be particularly sensitive to small drops in oxygen levels.
"The retina is very active at night - it has its highest need for energy while it recovers from the day," says Dr Abbott.
Many people diagnosed with sleep apnoea use a CPAP device at night, which helps them breathe easier by providing a constant flow of air through a mask.
"If people aren't currently getting treatment, it's putting them at risk over years of not sleeping properly and having low oxygen at night, which could be contributing factor to AMD, in particular wet AMD," says Dr Abbott.
Currently known risk factors for AMD include smoking status, diet, age and genetics.
Dr Abbott says the team will need to conduct larger studies to better understand this association and, if validated, will explore whether treating sleep apnoea has a clinically meaningful impact on reducing progression to wet AMD.
The work is part of the wider Synergy High Risk AMD Study, which is investigating AMD and the potential underlying causes that make some people more likely to lose their vision.
Read the research
Attiqa Chaudhary, Carla J Abbott, Zhichao Wu, Wendy Y Fang, Palaniraj R Raj, Matthew Naughton, Wilson J Heriot, Robyn H Guymer. Nocturnal hypoxia and age-related macular degeneration, Clinical and Experimental Ophthalmology, doi.org/10.1111/ceo.14428
A world-leading multidisciplinary research project, investigating age-related macular degeneration and the factors that make some people more likely to lose their vision.
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