Astronaut's eyeballs get squished

Trips to weightlessness can squash the eyeballs of astronauts, swell the optic nerves and blur vision — changes that often persist long after the astronauts return to weightbound Earth. That is one more health effect that NASA will have to worry about before astronauts venture farther out into the solar system...

Four of the 27 had some swelling around the optic nerve. In seven of the astronauts, the back of one or both of the eyeballs was somewhat flattened. Those abnormalities, Dr. Kramer said, resemble those in patients on terra firma who have a condition in which fluid pressure increases in the skull and presses against the eyes...

The flattening of the eyes is easily compensated for by eyeglasses, and nearsighted people become less nearsighted. But the M.R.I. scans also revealed little ripples in the back of the eyes of some of the astronauts, distorting their vision in a way that “would be more disconcerting to us,” Dr. Kramer said.

Further details at the New York Times and in the source article published in Radiology.