Space flight may be bad for your eyesight. Changes found in astronauts' eye tissue may cause vision problems, and possibly even blindness. As well as threatening the health of astronauts, this could jeopardise long-haul missions into space.
Larry Kramer of Texas Medical School in Houston and colleagues carried out MRI scans on 27 NASA astronauts after they had spent an average of 108 days in space. Four had bulging of the optic nerve, three had kinks in the nerve sheath, and six had flattening of the eyeball.
This is yet another serious physiological issue for any long duration human space flight with prolonged weightlessness. We need to be able to drastically reduce flight times by using a far more efficient propulsion technology that can accelerate the vehicle at near or greater than 1 g acceleration, or we will have to generate artificial gravity by spinning the space craft, which is technologically problematic. To read more, click here.