Here’s a health finding that isn’t likely to affect a large number of people, but it is troubling for a select few of the nation’s workforce: Prolonged space travel causes brain and eye abnormalities in astronauts.
The finding, which appears in the journal Radiology, is based on magnetic resonance imaging (MRI) of the eyes and brains of 27 astronauts who have spent prolonged periods of time in space.
The scans uncovered optical abnormalities similar to those that can occur in what’s known as “intracranial hypertension” -- a potentially serious condition in which pressure builds within the skull.
The astronauts were exposed to microgravity, or zero gravity, for an average of 108 days while on space shuttle missions and/or the International Space Station. Eight of the 27 astronauts underwent a second MRI exam after a second space mission that lasted an average of 39 days.
"The MRI findings revealed various combinations of abnormalities following both short- and long-term cumulative exposure to microgravity also seen with idiopathic intracranial hypertension," said Dr. Larry A. Kramer, professor of diagnostic imaging at The University of Texas Medical School at Houston. "These changes that occur during exposure to microgravity may help scientists to better understand the mechanisms responsible for intracranial hypertension in non-space traveling patients."
Among astronauts with more than 30 days in space, findings included: expansion of the cerebral spinal fluid space surrounding the optic nerve in nine of the 27 astronauts, flattening of the rear of the eyeball in six, bulging of the optic nerve in four and changes in the pituitary gland and its connection to the brain in three.
Bone mineral loss and muscle atrophy are also known effects of zero gravity on astronauts.