Rational and design of the REMOTE trial: An exploratory, pilot study to analyze REtinal MicrOcirculaTion in wEightlessness

Abstract

BACKGROUND: “Spaceflight associated neuro-ocular syndrome” (SANS) represents a challenging health condition in modern space medicine. Forty-eight percent of astronauts are diagnosed with SANS after long-term space missions. The pathophysiological mechanism seems to be multifactorial, and yet remains unknown. In this proof-of-concept study we plan to investigate retinal microcirculatory changes in weightlessness and aim to identify their role in the development of SANS. METHODS AND DESIGN: Healthy individuals will take part in a parabolic flight campaign, which recreates fractioned total weightlessness periods. The airplane is specifically equipped, and designed for the execution of parabolic flight maneuvers and scientific research in microgravity. Retinal microcirculation will be assessed with a modified fundus camera, which allows dynamic vessel analysis. We will additionally measure intra-ocular pressure and hemodynamic changes during each phase of the flight. Blood samples will be analyzed at baseline, one hour and 24 hours after exposure to weightlessness. CONCLUSIONS: This pilot study aims to investigate the feasibility of retinal microcirculation assessment during varying gravity. Results of this study may generate insights whether venous stasis in the eye, surrogated by the dilatation of retinal vessels and increase in intraocular pressure as signs of venous insufficiency, may potentially contribute to the development of SANS.

Acute and short-term fluctuations in gravity are associated with changes in circulatory plasma protein levels

“…The first parabola on each flight day was a test run for all research teams aboard. After this test run, the individual experiments were commenced following each researcher´s study protocol 29 . This means that in our experimental design, each test participant encountered 31 parabolas.…”

Changes in Ocular Perfusion and Pressure Changes in Gravitational Alteration Contribute to Spaceflight-Associated Neuro-Ocular Syndrome

“…A comprehensive description of the methods and equipment is published elsewhere. 5 Differences for all measurements across the different flight phases were compared using 1-way ANOVA for nonparametric data (Kruskal-Wallis test), followed by Dunn post hoc test. All tests are 2 sided, and a P value of <0.05 was considered as statistically significant.…”