Insights and an update on Spaceflight-Associated Neuro-ocular Syndrome
Discover Medicine, 2, 191 (2025). https://doi.org/10.1007/s44337-025-00421-7
Purpose A main concern of space agencies planning manned missions to the Moon
or Mars is visual impairment in the microgravitational environment. In a previous
review dating back to 2019 we provided an overview of this topic. In that paper, we
recalled that, aside from radiation, the most threatening menace for vision in space
is a prolonged condition of microgravity, responsible for the so-called Spaceflight-
Associated Neuro-ocular Syndrome (SANS), This review intends to update the previous
one, providing insights on its etiopathogenesis.
Methods Bibliographic research was carried out on PubMed, Google Scholar, and
other resources supporting biomedical literature, starting with the following keywords:
SANS, Spaceflight-Associated Neuro-ocular syndrome, Astronauts/Space + Eye/
Vision. The references in each selected paper were analyzed. Overall, 218 studies were
examined, 122 of them were considered suitable for our purposes.
Results SANS is a multifactorial syndrome caused by the cephalad fluid shift that
occurs in microgravity. This hemodynamic perturbation is assumed to lead to
compartmentalization of the cerebrospinal fluid in the subarachnoid perioptic space
associated with reduced glymphatic clearance, mildly elevated intracranial pressure
in some cases, and other pathophysiological phenomena. Risk factors have been
identified and further investigations are ongoing.
Conclusion A comprehensive understanding of the etiopathology of SANS and
identification of predisposing factors among astronauts is essential to mitigate or even
better neutralize its deleterious effects on the visual system, in the perspective of longduration
space missions on the Moon and the Red Planet.
Keywords Microgravity, Space-Associated Neuro-Ocular Syndrome, Intracranial
hypertension, Compartmentalization, Lymphatic, Risk factors
 Insights and an updated on SANS, Aleci and Dutto, Discover Medicine, 2025.pdf | 1908 kB |