Reduced Retinal Vessel Density in Obstructive Sleep Apnea Syndrome Patients: An Optical Coherence Tomography Angiography Study

PURPOSE. To examine the retinal vasculature in patients with obstructive sleep apneahypopnea syndrome ( OSAS) and to determine the correlation between retinal vascularity and the severity of OSAS. DESIGN. Prospective, cross-sectional study. METHODS. Sixty-nine consecutive subjects who underwent polysomnography were enrolled. Patients were divided into three groups according to the severity of OSAS, which was defined using the apnea-hypopnea index (AHI) as normal-to-mild (AHI < 15), moderate (< 15 to < 30), or severe (>= 30). The vessel densities, and macular and retinal nerve fiber layer thicknesses were compared among the three groups. The correlations between clinical variables (age, heart rate, body mass index, ocular perfusion pressure, spherical equivalence, IOP, inner retinal thickness, and AHI) and vessel densities were also determined. RESULTS. The full and inner parafoveal retinal thickness and the retinal nerve fiber layer thickness were similar in all three groups. The retinal vessel density decreased with greater severity of OSAS. The decrease in vessel density differed between the peripapillary and parafoveal areas. The moderate group had a significantly lower vessel density than the normalto- mild group in the peripapillary area (P < 0.05), but similar vessel density as the normal-tomild group in the parafoveal area (P > 0.05). The vessel densities in the parafoveal and peripapillary areas were significantly and negatively correlated with AHI (both P < 0.05); the relative reduction in vessel density was greater in the peripapillary area than in the parafoveal area. CONCLUSIONS. In OSAS patients, the vessel densities in the peripapillary and parafoveal areas decreased with greater disease severity, and the decrease was more prominent in the peripapillary area.