Moderate to severe obstructive sleep apnea tied to higher odds for neovascular AMD
Key takeaways:
- Individuals with moderate to severe obstructive sleep apnea had increased odds of having neovascular AMD.
- Nocturnal hypoxia may be a modifiable risk factor for neovascular AMD.
Moderate to severe obstructive sleep apnea was associated with significantly higher odds of having neovascular age-related macular degeneration, according to a study published in Clinical & Experimental Ophthalmology.
Given that nocturnal hypoxia is common in the same demographic as those at risk for AMD, previous studies have evaluated the association between obstructive sleep apnea (OSA) and AMD.
“We recently conducted a case-control study to investigate these associations, using sleep questionnaires, where we found that being on assisted breathing treatment for diagnosed OSA was significantly associated with a higher likelihood of having AMD with the RPD phenotype,” Attiqa Chaudhary, MBBS, of the Centre for Eye Research Australia at Royal Victorian Eye and Ear Hospital in East Melbourne and the department of surgery (ophthalmology) at the University of Melbourne in Victoria, and colleagues wrote.
“Sleep questionnaires are useful screening tools but are subjective in nature [and] have significant limitations and variability,” they added. “We therefore wished to further explore the relationship between OSA and AMD using more objective methods.”
To investigate the association between nocturnal hypoxia and AMD, AMD severity and the high-risk subphenotype of reticular pseudodrusen (RPD), Chaudhary and colleagues conducted a prospective, observational case-control study of 225 participants aged 50 years or older from natural history studies at the Centre for Eye Research Australia.
The researchers used multimodal imaging — including spectral domain-OCT, near-infrared reflectance, fundus autofluorescence and foveal-centered color fundus photography — to assess AMD status and severity.
To obtain nocturnal measurements of oxygen saturation, participants wore a wrist pulse oximeter on the same finger for 7 hours over 3 consecutive nights. The researchers classified OSA based on oxygen desaturation index, with values of 5 to 15 indicating mild OSA and values higher than 15 indicating moderate to severe OSA.
Overall, 76% (n = 171; mean age, 74 ± 8 years; 67% women) of participants had AMD, of whom 42% (n = 72) had coexistent RPD, and 24% (n = 54; mean age, 72 ± 9 years; 59% women) served as controls.
Among participants with AMD, 53% (n = 90) had early or intermediate AMD, 30% (n = 51) had geographic atrophy, and 17% (n = 30) had exudative neovascular AMD (nAMD).
According to the researchers, mild or moderate to severe OSA was not associated with increased odds of having AMD or AMD with RPD.
However, they did observe that moderate to severe OSA was associated with significantly higher odds of having nAMD (OR = 6.35; P = .032), but not early or intermediate disease or GA. Mild OSA was not associated with increased odds of having AMD of any severity.
“These findings may assist in providing much needed additional strategies to mitigate the risk of developing the severe vision-threatening late form of nAMD,” the researchers wrote. “Larger studies, including longitudinal studies, as well as studies with formal polysomnography, would further explore this association of nocturnal hypoxia with AMD.”
Chaudhary and colleagues acknowledged that one study limitation was the exclusion of people already on treatment for diagnosed OSA.
Perspective
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Research has shown that nocturnal retinal oxygen supply is particularly critical for optimal retinal health. It is hypothesized that decreased nocturnal oxygen levels could lead to retinal abnormalities like AMD. This study aimed to observe potential correlations between nocturnal hypoxia and varying severities of AMD with co-existent RPD phenotype. Nocturnal oxygen desaturation levels were measured by pulse oximetry over 3 nights to characterize sleep apnea severity. Moderate-to-severe sleep apnea was associated with increased risk of nAMD, but less severe sleep apnea was not associated with dry AMD nor RPD.This study provides researchers and clinicians with modifiable risk factors (eg, smoking history, BMI) when evaluating patients for AMD, especially those at higher risk of nAMD. A shortcoming is the exclusion of those with sleep apnea treated with CPAP machines, as this would confound pulse oximetry readings. This possibly under-represented concurrent sleep apnea and AMD. These results are less impactful, as it is unclear whether nocturnal hypoxia or sleep apnea is a risk factor for AMD. There was also significant variability in the data collected over the 3 nights. A longer study investigating patients diagnosed with formal polysomnography for sleep apnea could more accurately substantiate a correlation.
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