cervesaebraciator writes "Travel to Mars may face yet another hurdle and this one is not budgetary. A recent study published in the Journal of Radiology shows another risk associated with long-term space travel. In addition to the traditional threats of bone density loss, atrophy, and radiation from the Sun, astronauts who spend long periods in zero gravity may also face loss of vision. 27 astronauts who underwent MRI were found to suffer increased intracranial pressure. In particular, researchers found evidence, "for expansion of the cerebral spinal fluid space surrounding the optic nerve of nine of the astronauts, a flattening of the rear of the eyeball in six, a bulging of the optic nerve in four, and changes in the pituitary gland and its connection to the brain in three individuals.""
Link to Original Source