The goal of this study is to understand the impact of space travel on the eyes. Space flight impacts numerous aspects of ocular anatomy and physiology. Current hypotheses are based on pressure changes within and around the optic nerve. Retinal and choroid blood drainage may be affected by microgravity associated cerebrospinal fluid pressure changes. Recently, a new imaging modality, Optical Coherence Tomography Angiography (OCTA), has been able to reveal micro vascular changes in the retina and choroid. To date, no microgravity ocular imaging tests have been published using OCTA. In this study the researchers aim to describe microgravity circadian choroidal and retinal vasculature using multimodal imaging including OCTA to better understand space associated ocular changes.

Inclusion Criteria:

- astronauts in the AX1/Rakia mission, which was scheduled for space flight in late March 2022.

Exclusion Criteria:

• adults unable to consent
• individuals who are not yet adults (infants, children, teenagers) -
• pregnant women
• prisoners.

This study necessarily had a very specific population. The study only enrolled astronauts in the AX1/Rakia mission, which was scheduled for space flight in late March 2022.