Choroidal Blood Flow Regulation after Posture Change or Isometric Exercise in Men with Obstructive Sleep Apnea Syndrome

PURPOSE. Obstructive sleep apnea (OSA) syndrome generates hypertension, atherosclerosis, and endothelial and autonomic dysfunction, which may mutually interact with ocular vascular regulation. Exercise and posture changes can be used to manipulate blood pressure, ocular perfusion pressure (OPP), or both. It was hypothesized that choroidal vascular reactivity in response to isometric exercise and posture changes could be altered in OSA patients. METHODS. Healthy men were matched 1: 1 for body mass index, sex, and age with patients with newly diagnosed OSA without cardiovascular comorbidities. All subjects underwent sleep studies and cardiovascular phenotyping (24-hour blood pressure monitoring, arterial stiffness measurements, and cardiac and carotid echography). Choroidal reactivity was assessed by laser Doppler flowmetry, which measured subfoveal choroidal blood flow. RESULTS. During exercise, blood pressure parameters increased significantly within the same range, with a similar profile over time in OSA patients and control subjects. A significant linear relationship (P = 0.0003) was noted between choroidal vascular resistance and the OPP changes during exercise in OSA patients and control subjects. From the sitting to the supine position, a significant decrease in mean arterial pressure occurred in both groups (10.9%-13.4%; P = 0.001). In both populations, no significant change in choroidal blood flow or vascular resistance was found during the posture change. Choroidal blood flow responses to exercise and posture changes were unchanged after 6 to 9 months of continuous positive airway pressure treatment. CONCLUSIONS. This study strongly suggests that the regulation of choroidal blood flow, which depends on the orthosympathetic and parasympathetic systems, is unaltered in men with OSA who have no comorbidities. (ClinicalTrials.gov number, NCT00874913.) (Invest Ophthalmol Vis Sci. 2011; 52:9489-9496) DOI:10.1167/iovs.11-7936