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Anna Britton, Angela Schulz, Georgina Luscombe, Jessica Tong, Brendon Wong, Claude Farah, Stuart L Graham, Clare Fraser; Retinal vessel density changes in treated and untreated obstructive sleep apnoea. Invest. Ophthalmol. Vis. Sci. 2021;62(8):2476.
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Obstructive sleep apnoea (OSA) is a risk factor for vascular disease including stroke. Studies have shown OSA alters the retinal arterioles and veins, however studies on the microvasculature have yielded conflicting results and none have assessed the effect of continuous positive airways pressure (CPAP) on retinal vessel density. This prospective cohort study sought to examine the impact of varying severities of OSA on retinal vessel density using optical coherence tomography angiography (OCT-A) and whether CPAP treatment attenuates this change.
67 adult patients underwent diagnostic polysomnography and retinal vessel imaging between April 2015 – December 2016. Patients were stratified into four clinical severity groups based on their apnoea-hypopnoea index (AHI, events/hour): controls (<5), mild (≥5 to <15), moderate (≥15 to <30), and severe OSA (≥30). Following their sleep study a subset of patients were offered CPAP at the discretion of a sleep physician. At a 24-month follow up, patients had OCT-A scans taken on Spectralis OCT-A (Heidelberg Engineering, Germany). Vessel density was analysed on images of the macula and optic nerve head (ONH) using ImageJ software. Exclusion criteria included the presence of glaucoma, prior optic neuropathy or retinopathy and media opacities.
Of the 67 participants (45 males; mean age 62.3), there were 9 controls, 16 mild, 18 moderate and 24 severe OSA participants. Vessel density was negatively correlated with clinical severity by AHI but this did not reach statistical significance at the superficial vascular complex (SVC), deep vascular complex (DVC) or optic nerve head (ONH) (p = 0.072, 0.206, 0.294, respectively). However, for those not using CPAP, vessel density was significantly and negatively correlated by AHI at the macula (SVC p = 0.010, DVC p = 0.049). Compliant CPAP use abolishes this trend. Vessel density was also significantly and negatively correlated by AHI for diabetic patients in the cohort (SVC p = 0.013, DVC p = 0.042).
Our results show that retinal vessel density is negatively correlated with AHI in untreated individuals and that adequate use of CPAP abolishes this trend. Untreated OSA in combination with diabetes has the propensity to significantly worsen vascular outcomes.
This is a 2021 ARVO Annual Meeting abstract.
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