Functional optical coherence tomography at altitude: retinal microvascular perfusion and retinal thickness at 3,800 meters

Cerebral hypoxia is a serious consequence of several cardiorespiratory illnesses. Measuring the retinal microvasculature at high altitude provides a surrogate for cerebral microvasculature, offering potential insight into cerebral hypoxia in critical illness. In addition, although sex-specific diffe...

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Published in:	Journal of applied physiology (1985) Vol. 133; no. 3; pp. 534 - 545
Main Authors:	Baker, Jacquie, Safarzadeh, Mohammad A, Incognito, Anthony V, Jendzjowsky, Nicholas G, Foster, Glen E, Bird, Jordan D, Raj, Satish R, Day, Trevor A, Rickards, Caroline A, Zubieta-DeUrioste, Natalia, Alim, Usman, Wilson, Richard J A
Format:	Journal Article
Language:	English
Published:	United States American Physiological Society 01-09-2022
Subjects:	Altitude Altitude Sickness Ascent Blood flow Cardiovascular diseases Critical Illness Female Females High altitude High-altitude environments Humans Hypoxia Hypoxia, Brain Illnesses Male Males Measuring instruments Microvasculature Optical Coherence Tomography Perfusion Retina Sex Sex differences Thickness Tomography Tomography, Optical Coherence hypoxia high altitude functional optical coherence tomography cerebral microvasculature retinal microvasculature
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Summary:	Cerebral hypoxia is a serious consequence of several cardiorespiratory illnesses. Measuring the retinal microvasculature at high altitude provides a surrogate for cerebral microvasculature, offering potential insight into cerebral hypoxia in critical illness. In addition, although sex-specific differences in cardiovascular diseases are strongly supported, few have focused on differences in ocular blood flow. We evaluated the retinal microvasculature in males ( = 11) and females ( = 7) using functional optical coherence tomography at baseline (1,130 m) ( ), following rapid ascent ( ), and prolonged exposure ( ) to high altitude (3,800 m). Retinal vascular perfusion density (rVPD; an index of total blood supply), retinal thickness (RT; reflecting vascular and neural tissue volume), and arterial blood were acquired. As a group, rVPD increased on versus ( < 0.001) and was inversely related to [Formula: see text] ( = 0.45; = 0.006). By , rVPD recovered to baseline but was significantly lower in males than in females ( = 0.007). RT was not different on versus ( > 0.99) but was reduced by relative to and ( < 0.001). RT changes relative to were inversely related to changes in [Formula: see text] on ( = 0.6; = 0.001) and ( = 0.4; = 0.02). RT did not differ between sexes. These data suggest differential time course and regulation of the retina during rapid ascent and prolonged exposure to high altitude and are the first to demonstrate sex-specific differences in rVPD at high altitude. The ability to assess intact microvasculature contiguous with the brain has widespread research and clinical applications. Measuring the retinal microvasculature at high altitude provides a surrogate for cerebral microvasculature, offering potential insight into consequence of cerebral hypoxia in critical illness. This study demonstrates dynamic regulation of the retina during rapid ascent and prolonged exposure to high altitude and is the first to demonstrate sex-specific differences in retinal microvasculature at high altitude. The ability to dynamically assess intact microvasculature contiguous with the brain has widespread research and clinical applications.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	8750-7587 1522-1601
DOI:	10.1152/japplphysiol.00132.2022