Retinal vessel oxygen saturation in patients with unilateral internal carotid artery stenosis: a pilot study.

PURPOSE To investigate the retinal vessel oxygen saturation in patients with internal carotid artery stenosis (ICAS). METHODS This is a cross-sectional study. Sixteen patients with unilateral moderate or worse ICAS (≥50%) and no fundus diseases were included in the study. Sixteen gender- and age-matched healthy subjects were selected as controls. The mean oxygen saturation and vessel diameters of the retinal arterioles and venules were obtained using a dual-wavelength spectrophotometric retinal oximeter. RESULTS In the eye of the stenotic side, the retinal vessel oxygen saturation was 100.14 ± 10.27% in the arterioles and 56.50 ± 10.79% in the venules, and the arteriovenous (A-V) difference was 43.63 ± 7.71%. In the eye of the contralateral side, the oxygen saturation was 96.55 ± 7.50% in the arterioles and 57.42 ± 9.84% in the venules, and the A-V difference was 39.39 ± 6.33%. In healthy subjects, the oxygen saturation was 93.22 ± 5.98% in the arterioles and 56.57 ± 7.05% in the venules, and the A-V difference was 36.65 ± 7.33%. The arteriolar oxygen saturation in the stenotic side was higher than that in the contralateral side (p = 0.025) and that in the healthy subjects (p = 0.027), and the A-V difference in the stenotic side was significantly higher than that in the contralateral side (p = 0.009) and that in the healthy subjects (p = 0.013). The diameters of the arterioles in the stenotic side were smaller than those in the healthy subjects (p = 0.030). CONCLUSIONS Patients with ICAS had decreased retinal arteriole diameters and increased retinal vessel oxygen saturation in the arterioles and A-V differences, suggesting the presence of microcirculation disorder and hyperoxia in the retina.