Impact of Continuous Positive Airway Pressure Treatment on Retinal Vasculature in Obstructive Sleep Apnea: A 7-Year Follow-Up

Abstract

Purpose: In previous studies, obstructive sleep apnea (OSA) severity at diagnosis was independently associated with retinal arteriolar narrowing and reduced retinal pulse amplitude. Participants with severe untreated OSA showed progressive retinal arterial narrowing 2 years post diagnosis, while the use of continuous positive airway pressure (CPAP) ventilation appeared to attenuate these changes. This 7-year prospective study examines whether these protective effects of CPAP persist. Methods: We invited 79 participants from the 2-year follow-up cohort for a 7-year review. Of these, 39 completed assessments: medical history, optical coherence tomography, and retinal vessel imaging. The retinal nerve fiber layer (RNFL) thickness, central retinal artery equivalent (CRAE), central retinal vein equivalent (CRVE), and arteriovenous ratio were analyzed. Results: CRAE and CRVE appeared greater in patients with severe OSA + CPAP than untreated OSA. Over 7 years, CRVE observably declined more slowly in severe those with OSA + CPAP than those with untreated severe OSA. Severe OSA + CPAP had a notable smaller decline in CRAE comparison with the control and untreated groups. The RNFL thickness was nonsignificantly reduced in severe OSA + no CPAP compared with those with CPAP in the superotemporal sector. Global RNFL rates of thinning were equivalent across groups. There was a trend for those not on CPAP to have higher rates of hypertension and stroke. Conclusions: In this cohort, the cohort size was too small for robust statistics. It can still be broadly appreciated that CPAP provides long-term protective benefit against retinal arterial narrowing. The protective effect of CPAP on retinal vascular changes seen at the 2-year mark continued to trend in the mean CRAE values and was also potentially demonstrated in preservation of RNFL thickness in this 7-year study.