Space could leave you blind

A mysterious syndrome has been impairing astronauts’ vision on the International Space Station, causing untreatable nearsightedness that lingers for months even after they’ve returned to Earth.

The problem is so bad that two-thirds of astronauts report having deteriorated eyesight after spending time in orbit. Now scientists say they finally have some answers – and it’s not looking good for our prospects of getting to Mars.

http://www.sciencealert.com/we-finally-know-why-astronauts-lose-their-vision-in-space-and-it-s-bad-news-for-mars-missions