Space travel affects optic nerve

Researchers from the College of Optometry at the University of Houston found that the optic nerves are subjected to dangerous pressure levels, evidenced by the Bruch mbrane openings showing signs of the optic nerve tissues being pushed deeper into the eye.The discovery was made after analysing the eyes of 15 astronauts who had undertaken long-term space missions of up to six months. The researchers took OCT scans both pre- and post-flight, which showed an increase in total retinal thickness.The tissue at the back of their eyes, which surround the heads of the optic nerves, also appeared warped and swollen in the weeks after their return to Earth.While previous research has donstrated space travel changes the shape of the eye, the new study is the first to show direct, damaging changes to the optic nerve.The researchers were not sure what causes this damage, but suggested internal pressure in the eye increases while in space, which the surrounding tissues adapt to over time.However, upon returning to earth, gravity suddenly roves the pressure, in turn causing irritation and potentially deforming the internal tissue of the eye.The results of the study could explain why many astronauts develop vision probls after completing their space missions.