To the Editor We read with great interest the article by Marshall-Goebel et al.1 We are grateful to the authors for sharing their valuable data with the scientific community and appreciate the opportunity to comment.
The authors sought to determine if there is an association between quantitative changes in intracranial compartment volumes and peripapillary total retinal thickness (TRT), a quantitative assessment of optic disc edema (ODE), after spaceflight. They reported a weak positive association between increases in TRT and lateral ventricle volume after spaceflight. They concluded that while weightlessness-induced fluid redistribution during spaceflight may be a common stressor to the brain and retina, the development of ODE appears to be uncoupled with changes occurring in the intracranial compartment, and that alterations in cerebrospinal fluid (CSF) distribution that likely underlie brain structural changes are not the main cause of ODE in astronauts.