Scott Kelly spent a year aboard the International Space Station starting in 2015. Scott Kelly spent a year aboard the International Space Station starting in 2015. Scott Kelly spent a year aboard the International Space Station starting in 2015. (Photo: NASA/Getty Images)

How long space flights ruin astronauts' vision

A new study points to a cause of vision impairments in astronauts who have spent a long time in space.

What happens to astronauts' bodies after they spend a long time in space?

It's a hot topic in the aerospace field right now, thanks to popular TV series like "Mars" and the exciting work of "astronaut twins" Mark and Scott Kelly. Scott just completed a year aboard the International Space Station, the longest any American has ever spent in orbit.

Astronauts Mark and Scott Kelly. (Photo: Bill Ingalls/NASA via Getty Images)Astronauts Mark and Scott Kelly. (Photo: Bill Ingalls/NASA via Getty Images)

And as astronauts like the Kelly brothers take on increasingly longer missions in space, NASA's flight surgeons and scientists have noticed a peculiar pattern in the returning crew: blurry vision.

The study's lead author is Dr. Noam Alperin, a graduate of Tel Aviv University who's now a professor of radiology and biomedical engineering at the University of Miami. "People initially didn't know what to make of it, and by 2010 there was growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to Earth," he said.

So the Israel-born Alperin decided to take a closer look at this space-induced visual impairment. After years of research, he and his colleagues presented their findings this week at the annual meeting of the Radiological Society of North America in Chicago.

Dr. Noam Alperin has been studying the optical effects of long-duration space flight for years.Dr. Noam Alperin has been studying the optical effects of long-duration space flight for years. (Photo: Radiological Society of North America)

Among the findings is a clearer picture of what is actually happening to the astronauts' eyes – and brains – during their space missions. Testing revealed that the backs of their eyeballs came back flatter, and the head of the optic nerves was inflamed. The condition now has a name: visual impairment intracranial pressure (VIIP). Two-thirds of the astronauts who served long missions aboard the International Space Station presented this syndrome.

What's interesting about this finding is that it topples previous research of visual impairment in astronauts. Scientists once thought that vascular fluid was shifting toward the upper body, a result of microgravity, causing the eye changes. But Alperin said that's not the case. What is actually happening is that their cerebrospinal fluid, which normally tolerates a wide range of pressure changes on Earth, is not equipped to handle such drastic changes in space. Essentially, it's "confused," Alperin explained.

"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," Alperin said.

So why is this discovery so important? Alperin said it's all about early identification to avoid "irreversible damage" and test "countermeasures." Knowing the potential for damage after an astronaut spends a long time in space can help doctors treat any problems when he or she returns.

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How long space flights ruin astronauts' vision
A new study points to a cause of vision impairments in astronauts who have spent a long time in space.