Choroidal blood flow regulation after posture change or isometric exercise in men with obstructive sleep apnea syndrome.
OBJECTIVE
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.
Department of Ophthalmology, University Hospital, Université Joseph Fourier, Grenoble, France.
Hafid
H
Khayi
Jean-Louis
JL
Pepin
Martial H
MH
Geiser
Matthieu
M
Tonini
Renaud
R
Tamisier
Elisabeth
E
Renard
Jean-Philippe
JP
Baguet
Patrick
P
Levy
Jean-Paul
JP
Romanet
Christophe
C
Chiquet
D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002829:Choroid / Q000098:blood supply* / Q000503:physiopathology; D045422:Continuous Positive Airway Pressure; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012039:Regional Blood Flow / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000503:physiopathology* / Q000628:therapy; D014655:Vascular Resistance / Q000502:physiology