A Centre for Eye Research Australia (CERA) study has linked low levels of oxygen in the blood overnight – a common sign of obstructive sleep apnoea – with wet age-related macular degeneration.
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).
A CERA media release said University of Melbourne Master’s student MrAttiqa 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 release said 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 obstructive sleep apnoea was calculated based on the oxygen levels in their blood overnight.
The results showed that moderate-to-severe obstructure sleep apnoea, 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 the condition.
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 said in the release.
“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 sleep apnoea, as treating it might reduce the risk of developing wet macular degeneration.”
Nocturnal hypoxia often occurs as a result of obstructive sleep apnoea, 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.
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 macular degeneration and the potential underlying causes that make some people more likely to lose their vision.
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