Choroidal Blood Flow Response to Isometric Exercise in Patients With Obstructive Sleep Apnea Syndrome

Abstract

Purpose: : Obstructive sleep apnea syndrome (OSA) has been recently reported as associated with ischemic and glaucomatous optic neuropathy. The common underlying mechanism of these diseases is an abnormal regulation in the optic nerve head vasculature. The aim of our study was to characterize the choroidal vascular reactivity to acute increases in ocular perfusion pressures (OPP) induced by squatting exercise in OSA patients.

Methods: : Fifteen newly diagnosed OSA patients were prospectively included as well as control subjects matched for body mass index (BMI), gender and age. At baseline, each subject underwent general, cardiovascular, neurologic and ophthalmological examinations, and were assessed by complete overnight polysomnography. The LDF instrument used in this study to measure subfoveal choroidal blood flow (ChBF) measured the following parameters: velocity, ChBVel (kHz); volume, ChBVol (in arbitrary units, AU) and the relative flow, ChBF = ChBVel × ChBVol (in AU). Vascular choroidal reactivity was tested during squatting.

Results: : OSA patients exhibited a similar choroidal reactivity during increase in OPP (i.e. stability of choroidal blood flow) than controls until an increase of OPP about 145%. For an increase in OPP higher than 145%, OSA patients did not exhibit an increase in blood flow in contrast to healthy subjects.

Conclusions: : This prospective comparative study explored for the first time the choroidal blood flow of OSA patients and showed that subfoveal ChBF reactivity to exercise in OSA patients differed from healthy subjects for the highest OPP elevations. These preliminary results suggest an impaired relaxation of choroidal vasculature in OSA patients possibly explained by the chronic sympathetic activation characteristic of the disease.

Clinical Trial: : www.clinicaltrials.gov NCT00874913

Keywords: blood supply • choroid • pathology: human