For years now, NASA has been puzzled by the vision damage experienced by astronauts who spend time on extended space flights. Many astronauts who have been in space for months at a time experience slowly degrading vision. Now, post-flight inspection reveals that the back of their eyeballs have been “squished down and flattened over the course of their trip.”
New research presented this week provides a partial answer to what’s causing this condition: pressurized spinal fluid. Noam Alperin, a researcher at the University of Miami’s Evelyn F. McKnight Brain Institute, presented findings from research he and his peers conducted on 16 astronauts, measuring the volume of cerebrospinal fluid (CSF) in their heads before and after spaceflight. CSF floats around the brain and spine, cushioning it and protecting your brain as you move, such as when you stand up after lying down.
Alperin and his team found that astronauts who had been in space for extended trips (about six months) had much higher build up of CSF in the socket around the eye than astronauts who had only gone on short stints (about two weeks). They also designed a new imaging technique to measure exactly how “flat” the astronauts eyeballs had become after extended periods in space.
The idea is that, without the assistance of gravity, the fluid isn’t pulled down and evenly distributed, allowing it to pool in the eye cavity and build up pressure, which slowly starts to warp the eye and cause the vision damage, called visual impairment intracranial pressure syndrome (VIIP).
Many astronauts have experienced this unexplained reduction in eyesight after spending months on the International Space Station, some dropping from perfect 20/20 vision to 20/100 in just six months.
With plans to send humans to Mars by the 2030s, a mission that would require nine months of space flight one way, we don’t really want to risk all of our astronauts going blind in the process.
“NASA ranks human health risks and the two top risks are radiation and vision issues,” Smith said.
What a solution to the condition will look like depends what else we learn: it could be a medication, or a mechanical device to help redistribute fluid, or something else entirely. But each piece to the puzzle helps us get one step closer to sending humans to Mars, and not blinding them in the process.
Photo below: NASA astronaut Michael Hopkins performs eye imaging on the International Space Station.