宇宙飛行士のおかげで目について学ぶ研究者たち(Researchers Learning More About Eyes Thanks To Astronauts)

2024-06-20 テキサス A&M大学

<関連情報>

• https://today.tamu.edu/2024/06/20/researchers-learning-more-about-eyes-thanks-to-astronauts/
• https://www.nature.com/articles/s41526-024-00404-5

眼灌流圧は下半身陰圧に反応して低下しない Ocular perfusion pressure is not reduced in response to lower body negative pressure

Eric A. Hall,Richard S. Whittle & Ana Diaz-Artiles
npj Microgravity  Published:08 June 2024
DOI:https://doi.org/10.1038/s41526-024-00404-5

Abstract

Lower body negative pressure (LBNP) has been proposed as a countermeasure to mitigate the cephalad fluid shift occurring during spaceflight, which may be associated with the development of Spaceflight Associated Neuro-ocular Syndrome (SANS). This study quantifies the effect of LBNP on intraocular pressure (IOP), mean arterial pressure at eye level (MAP_eye), and ocular perfusion pressure (OPP). Twenty-four subjects (12 male, 12 female) were subjected to graded LBNP in 0° supine and 15° head-down tilt (HDT) postures from 0 mmHg to –50 mmHg in 10 mmHg increments. IOP decreased significantly with LBNP pressure in 0° supine (by 0.7 ± 0.09 mmHg per 10 mmHg LBNP pressure, p < 0.001) and in 15° HDT (by 1.0 ± 0.095 mmHg per 10 mmHg of LBNP pressure, p < 0.001). MAP_eye significantly decreased by 0.9 ± 0.4 mmHg per 10 mmHg of LBNP pressure in 0° supine (p = 0.016) but did not significantly change with LBNP in 15° HDT (p = 0.895). OPP did not significantly change with LBNP in 0° supine (p = 0.539) but it significantly increased in 15° HDT at 1.0 ± 0.3 mmHg per 10 mmHg of LBNP pressure (p = 0.010). Sex did not have a significant effect on OPP, MAP_eye, or IOP in any condition. In 15° HDT, the reduction in IOP during increasing negative pressure, combined with the relatively constant MAP_eye, led to the increase in OPP. Furthermore, results suggest that LBNP, while effective in reducing IOP, is not effective in reducing OPP across all postures investigated.