Figure 2. Changes in Optic Nerve Head Morphology During Spaceflight.

A, Minimum rim width increased on flight day (FD)50 and FD150 and gradually recovered after return to Earth, with no difference from the preflight baseline by return to Earth (R) + 180. B, Cup volume followed a similar timeline as minimum rim width, initially decreasing on FD50 and returning to baseline by R + 180. C, Bruch membrane opening (BMO) height was significantly reduced (ie, posteriorly displaced) on FD150 but did not differ from baseline at any other time point. Circles show all individual subject data representing data obtained on Earth (white), data obtained during spaceflight (light gray), and the participant with Frisén grade 1 disc edema (dark gray); this individual did not have a detectable optic cup and was therefore excluded from the cup volume analysis. Horizontal bars represent the estimated marginal mean values across participants, and error bars represent the 95% CIs. P values for the change relative to the preflight seated baseline value are provided in eTable 1 in the Supplement. Statistics were not performed on FD250 data owing to the small sample size (n = 4).