Wong B, Tong JY, Schulz AM, et al. - Researchers conducted this prospective cohort study for analyzing the impact of continuous positive airway pressure (CPAP) treatment on retinal vascular changes in patients with obstructive sleep apnea (OSA). Participants in the study were adult patients undergoing diagnostic polysomnography at a tertiary sleep clinic in Sydney, Australia. Seventy-nine patients partook in this follow-up study, with 9 controls, 18 mild, 21 moderate, and 31 severe OSA patients. Twenty-five patients had started CPAP after baseline. It did not appear that CPAP had a major effect on venous calibre or vascular pulsatility. This investigation shows that progressive retinal arterial narrowing is demonstrated in patients with severe untreated OSA, and CPAP treatment may be protective.