http://www.businessinsider.com/what-happens-to-your-eyes-in-space-2016-7Astronauts are returning from space with mysterious eye problems
ScienceAlert
Fiona MacDonald, ScienceAlert
Space does plenty of whacky things to astronauts' bodies, like deteriorating their muscle mass and making them on average 5 centimeters (2 inches) taller.
But scientists have uncovered another, more subtle side effect — space is totally ruining astronauts' perfect eyesight.
In fact, 80 percent of astronauts who come back from long-duration missions display symptoms of a mysterious eye condition that causes nearsightedness, Shayla Love reports for The Washington Post.
While it's a myth that all astronauts have to have natural 20/20 vision (they're allowed to have corrective laser surgery) by the time they launch, their vision does need to be flawless — so this problem could be a big issue for future human spaceflight missions, like the one hoping to get humans to Mars by the 2030s.
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