The impact of continuous positive airway pressure treatment on retinal vascular changes in obstructive sleep apnea

Abstract

Obstructive sleep apnea (OSA) was recently shown to be associated with quantifiable retinal vascular changes, which correlate with disease severity. This follow-up study examines the response of retinal vascular changes in patients with OSA receiving continuous positive airway pressure (CPAP) treatment. This prospective cohort study recruited adult patients undergoing diagnostic polysomnography at a tertiary sleep clinic in Sydney, Australia, stratified into 4 groups by the apnea-hypopnea index; control patients and patients with mild, moderate, and severe OSA. At baseline and follow-up approximately 24 months later, static retinal vascular calibers were derived from fundus photographs, and dynamic vascular pulsation amplitudes were measured on video fundoscopy. A proportion of patients started CPAP therapy after baseline assessment. Seventy-nine patients participated in this follow-up study: 9 control patients and 18 patients with mild OSA, 21 patients with moderate OSA, and 31 patients with severe OSA. Twenty-five patients started CPAP after baseline. In the severe group, patients not on treatment showed progressive narrowing of retinal arteries from baseline, whereas those on CPAP showed a slight improvement (mean, 171.3-165.1 and 171.2-174.0 μm, respectively; P = .012). Arterio-venous ratio was also significantly reduced in the nontreatment group compared to the treatment group in those with severe OSA (0.836-0.821 and 0.837-0.855, respectively; P = .031). CPAP did not seem to have a significant impact on venous caliber or vascular pulsatility. This study shows that patients with severe untreated OSA demonstrate progressive retinal arterial narrowing, whereas CPAP treatment may be protective.