Staying in Space Might Be Bad For Humans After All, Here's Why

A new study revealed that human who have stayed in space for long period of times are at risk of developing visual problems due to volume changes in the clear fluid located around the brain and the spinal cord.

The study, presented at the 102^nd Scientific Assembly and Annual Meeting of the Radiological Society of North America, showed that astronauts who have spent lengthy missions in space may suffer from visual impairment intracranial pressure, which could lead to blurry vision.

"The research provides, for the first time, quantitative evidence obtained from short- and long-duration astronauts pointing to the primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome," explained Noam Alperin, Ph.D., professor of radiology and biomedical engineering at the University of Miami Miller School of Medicine and lead author of the study, in a press release. "If the ocular structural deformations are not identified early, astronauts could suffer irreversible damage."

CSF, or the cerebrospinal fluid, is the clear fluid that cushions the brain and the spinal fluid during significant changes in hydrostatic pressures. However, the lack of pressure-related posture changes in the microgravity of space confuses the CSF system.

For the study, the researchers performed high-resolution orbit and brain MRI scans before and shortly after spaceflights for seven long-duration mission ISS astronauts. They then compared the results of the earlier scans to short-duration mission space shuttle astronauts.

The researchers observed that the post-flight orbital and ventricular CSF volume of long-duration astronauts have significantly increased compared to short-mission astronauts. Additionally, astronauts who spend more time in space have significantly increased post-flight flattening of their eyeballs and increased optic nerve protrusion.

The orbital CSF volume is the CSF around the optic nerves within the bony cavity of the skull that holds the eye, while the ventricular CSF volume is located in the cavities of the brain where CSF is produced. The researchers linked these increases in the intraorbital and intracranial CSF volume to the large post-spaceflight ocular changes observed in ISS crew members.

With their findings, the researchers hope to develop countermeasures to prevent space-induced ocular deformities to protect astronauts working at the ISS and manned-satellites against ill-effects of long duration in microgravity.