Going into space crushes the delicate nerves in your eyeballs
Astronaut Ed White performed the first American spacewalk during the Gemini 4 mission on June 3, 1965. Credit: NASA
Two delicate, bundled stalks of nerve tissue erupt forward from the brain, slip between gaps in the backs of each eyeball, and attach themselves gently to the rear of each retina. These are the optic nerves, the transmitters linking human beings to their powers of sight. And now researchers have shown that space travel puts a powerful, dangerous squeeze on their fragile tips.
A study of 15 astronauts who had been on missions in orbital freefall for about six months found that the tissues at the backs of their eyes — tissues that surround the heads of their optic nerves — tended to look warped and swollen in the weeks after their return to Earth. This change could help explain why nearly half of long-term space travelers develop significant vision problems, according to the study, published today (Jan. 11) in the journal JAMA Ophthalmology.
This isn't the first study to demonstrate that space travel changes the shape of the eye; a 2011 paper published in the journal Ophthalmology showed that there were changes to the internal anatomies of astronauts' eyes. But the new study is the first to show direct, damaging changes to the optic nerve.
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