Astronauts have complained for decades about vision problems such as blurriness following trips into space. A recent NASA survey of 300 astronauts found correctible near and distance vision problems in 48 per cent of astronauts who had been on extended missions and 23 per cent of those who had been on brief missions. In some cases, they lasted for years after the astronauts returned to Earth
I've heard about this in the past but never thought too much about it, now I can't help but think this could be a major hurdle to overcome before we can safely traverse space for commercial purposes.
Then there is a little part of me that is saying "ALIENS, ALIENS could have been humans exposed to space too long!