Study Explains Why Astronauts Suffer Visual Impairment After Long Space Missions

Posted: Nov 28 2016, 9:57am CST | by , Updated: Nov 28 2016, 10:02am CST , in Latest Science News


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Study Explains Why Astronauts Suffer Eye Impairment after Long Space Missions
Credit: Radiological Society of North America

The eye problems of astronauts are linked to changes in the volume of clear fluid

Venturing into low-gravity space environment can have negative effects on eyes, too.

Over the last decade, a number of astronauts have reported blurry vision after returning to Earth. Further testing has also showed changes in their eye structure and gene expression. An eye disease, known as visual impairment intracranial pressure (VIIP), has been found in almost two-thirds of astronauts coming from long-duration missions aboard International Space Station.

More importantly, the condition persisted despite staying on Earth, prompting concerns over future deep space missions mars and beyond.

“People initially didn't know what to make of it, and by 2010 there was growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to earth.” Study lead author Noam Alperin, professor of radiology and biomedical engineering at the University of Miami said.

Previously, it was thought that the problem was caused by the shift of vascular fluid toward the upper body – a condition that takes place when astronauts spend time in microgravity of space. But recent investigation has found another source for the problem. This is the clear fluid that protects brain and spinal cord while circulating nutrients and removing waste materials from body.

This system is especially designed to accommodate significant pressures triggered by a person’s lying to sitting or standing position. But the lack of poster-related pressures in microgravity conditions of space is likely disturbing the system.

To find any correlation between changes in clear fluid or cerebrospinal fluid (CSF) and visual impairment after space flights, researchers scanned the brains of astronauts before and after several long-duration missions onboard ISS. When those scans were compared with the brain MRIs of astronauts returning from short duration spaceflights, a number of significant changes were noticed.

Researchers found that long duration astronauts not only had increased flattening of eyes and swelling of optic nerve but they also showed greater changes in clear fluid volumes within the skull that is responsible for holding the eye.

“The research provides, for the first time, quantitative evidence obtained from short- and long-duration astronauts pointing to the primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome,” said Dr Alperin.

“If the ocular structural deformations are not identified early, astronauts could suffer irreversible damage. As the eye globe becomes more flattened, the astronauts become hyperopic, or far-sighted.”

The findings will help NASA to prepare for health hazards before humans take the next giant step to Mars.

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<a href="/latest_stories/all/all/47" rel="author">Hira Bashir</a>
The latest discoveries in science are the passion of Hira Bashir (). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.




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