In 2005, astronaut John Phillips took a break from his work on the International Space Station and looked out the window at Earth. He was about halfway through a mission that had begun in April and would end in October.

When he gazed down at the planet, Earth was blurry. He couldn’t focus on it clearly. That was strange — his vision had always been 20/20. He wondered: Was his eyesight getting worse?

“I’m not sure if I reported that to the ground,” he said. “I think I didn’t. I thought it would be something that would just go away, and fix itself when I got to Earth.”

It didn’t go away.

During Phillips’s post-flight physical, NASA found that his vision had gone from 20/20 to 20/100 in six months.

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