An astronaut's weight may play a role in ocular changes that occurs during spaceflight and can lead to vision impairment new research suggests. The study led by Jay C. Buckey at Dartmouth College in New Hampshire US showed that reduced gravity levels (microgravity) in space can lead to spaceflight-associated neuro-ocular syndrome (SANS) in some astronauts. SANS refers to structural changes in the eye that may impair vision including swelling of the optic nerve (optic disc edema) and coloured indentations (choroidal folds) in the blood vessel network at the back of the eye. Read: Have eye pain? Here s what you