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Some Astronauts’ Eyeballs Are Deformed After Spaceflight. Here’s Why.
published during a waxing crescent moon.
12/02/2016

For a few years now, astronauts returning to Earth have noticed something strange; they don’t see the world the same way as they used to. Literally.

Astronauts’ Eyeballs

Can you see me now? Astronauts who spend longer amounts of time in space are more likely to experience eye damage. Credit: NASA

Some (not all) astronauts end their spaceflight with a permanent change in vision, becoming far sighted instead of near-sighted, or needing different prescriptions for their glasses or contacts. The condition is tentatively called visual impairment intracranial pressure or VIIP. VIIP affects two out of three astronauts who were on long-term missions the ISS.

Astronauts’ Eyeballs

Steve Swanson undergoes an eye exam on the ISS. Credit: NASA

Now, researchers think they may have figured out why. In results presented at the annual meeting of the Radiological Society of North America, researchers say that the fluid in astronauts brains may be physically deforming the back of the astronaut’s eyeballs, flattening out the natural curve, and changing the astronaut’s vision in the process.

On Earth, cerebrospinal fluid helps cushion the brain from stress or damage, constantly adjusting along with your posture as you go from walking to sitting to lying down. In space, where gravity isn’t there to give the fluid its cues, the volume of fluid can build up in the brain, pushing on the eyes themselves and altering their shape.

Astronauts’ Eyeballs

The eyes have it: Astronaut Tom Marshburn prepares for launch in 2012. Recent studies show that astronauts like Marshburn may suffer from impaired vision over long periods of time in space.

Damage to eyes has been noticed in astronauts and mice for a few years now. Figuring out the cause of the visual damage, as well as potential ways to repair the damage are critical, especially because the risk of injury seems to increase with the length of time spent in space.

As countries and companies around the world set their sights on Mars, and longer and longer missions in space or low-gravity environments, understanding how the human body reacts in space is of vital importance. Vision problems are only the tip of the iceberg. While researchers will continue to examine the causes of vision damage, there are other health concerns to worry about as well, including radiation exposure, and muscle loss.