Astronauts experience blurry vision after long space flights because of the changes their bodies undergo in space, claims a new study. The study, commissioned to investigate complaints from cosmonauts about impaired eyesight, has revealed that microgravity could be causing erratic movement of the spinal fluid resulting in deteriorated vision.
Scientists have long suspected astronauts who are sent on long duration space missions, including those to Mars, could go blind by the time they reach the Red Planet. According to the official statistics nearly two-thirds of astronauts who have gone on long-duration space missions have returned with one of the many eye problems. While a majority of the spacemen complained of blurry vision, there were cases of flattened eyeballs and inflamed optic nerves as well. Needless to say, these visual impairments are a cause of great concern since eyesight is one of the most crucial senses that astronauts have to rely on, and losing the ability could be disastrous in the vast emptiness of space, where there is no hospital to remedy the situation before it causes long-term and permanent damage.
Researchers studying the concerning problem, have a new hypothesis to suggest why veteran astronauts like Scott Kelly admitted that he, like many of his colleagues, came back to Earth with vision troubles. The researchers suggest changes in spinal fluid that occur while in microgravity could be the cause behind quite a few astronauts experiencing blurry vision and impaired eyesight after long spaceflights. Shockingly, “some of the astronauts had severe structural changes that were not fully reversible upon return to Earth,” noted lead researcher Noam Alperin, professor of radiology and biomedical engineering at the University of Miami Miller School of Medicine.
We're helping astronauts "see" how to live & work in space. Eye exams for a Fluid Shifts experiment may explain crew vision changes. pic.twitter.com/5gL6ytD6gq— NASA Marshall News (@NASA_Marshall) November 29, 2016
Officially recognized as “Visual Impairment Intracranial Pressure Syndrome” or VIIP, researchers previously believed bodily fluids that are normally dragged downwards due to gravity here on Earth, act very strange in microgravity. Instead of following the laws of biology and nature, the fluid travels randomly, flowing freely into the head. Once there, it starts to build pressure on the brain. Eventually the fluids settle near the eyeballs, causing impaired vision.
A new study involving 16 astronauts doesn’t thrash the old hypothesis, but narrows down on the type of body fluid. While previously the vascular fluids bubbling up to the head were believed to be the culprit, scientists now believe it is the sloshing cerebrospinal fluid tipping toward the eyes, reported Ars Technica. The new study’s findings were presented by researchers from the University of Miami at the annual meeting of the Radiological Society of North America in Chicago on Monday.
Astronauts develop worse vision after long trips in space, and scientists think they know why - Quartz https://t.co/3FncLZC4AZ— Universe and Spaces (@UniverseSpaces) November 29, 2016
To confirm their theory, Alperin and colleagues studied before and after brain scans of seven astronauts who had spent multiple months aboard the International Space Station (ISS). They compared the scans to those of nine astronauts who made short trips up and back aboard the U.S. space shuttle. A comparison of the scans revealed long-duration astronauts had noticeably more cerebrospinal fluid (CSF) in the brain, reported Yahoo.
Incidentally, the spinal fluid is very important under normal circumstances. Besides circulating nutrients and removing waste materials, the clear fluid cushions the brain from pressure changes during movements. The fluid is designed to protect the brain by compensating for the changes in pressure that occur during mundane everyday activities like getting up from bed, and standing up, noted Alperin.
“On Earth, this spinal fluid system is designed to accommodate changes whether a person is sitting, standing or lying down. But in space, the system is confused by the lack of the posture-related pressure changes.”
In other words, microgravity confuses the spinal fluid. The researchers were able to establish a correlation between changes in fluid volumes and eye structure using advanced imaging algorithms.
[GIZMAG] Changes in cerebrospinal fluid volume the culprit behind astronauts' blurry vision https://t.co/gP31gblRbT— David Papp (@DavidPapp) November 29, 2016
Interestingly, the study didn’t find any changes in grey matter or white matter volume in either group of astronauts, reported the Daily Mail.
[Featured Image by Christiane Heinicke/NASA/Getty Images]