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Mathilde Gallice, Thierry Zhou, Florent Aptel, Samuel Verges, Martial Henry Geiser, Jean Paul Romanet, Christophe Chiquet; OPTIC NERVE HEAD AND CHOROIDAL VASOREACTIVITY TO HYPOXIA IN HEALTHY HUMANS. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4858.
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© ARVO (1962-2015); The Authors (2016-present)
Optic nerve head (ONH) and choroidal (Ch) vasoreactivity to hypoxia is not clearly defined, although it is a common pathological situation in diabetic retinopathy, retinopathy of prematurity, open-angle glaucoma or in systemic diseases. We measured ocular blood flow changes in response to acute hypoxia in healthy humans.
Using confocal laser Doppler flowmetry, ONH and Ch blood flow were measured under hypoxia condition during 15 minutes (FiO2 10,5%) in order to reach a stable 85% SpO2. PetCO2, blood pressure, and respiratory rate were monitored during the experiment.
Fourteen young (28±6 years ) healthy subjects were included. In response to 85% hypoxia, ONH blood flow increased of +11% [−2.4; 34] (median and interquartiles interval, p=0.08) mainly due to an increase in ONH velocity +18% [6; 27] (p=0.004). Choroidal LDF parameters did not significantly differ during hypoxia (p=0.2 for Ch flow, p=0.3 for Ch volume, and p=0.12 for Ch velocity). Respiratory rate or arterial pressure did not significantly change during experiment.
The response of ONH to hypoxia is close to that described for the retina. The absence of choriocapillaris vasoreactivity to hypoxia, despite a significant decrease in tissue oxygen partial pressure, could be explained by the conterbalanced vasoconstriction associated with the activation of the autonomic nervous system during hypoxia.
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