'33% decrease': NASA's Sunita Williams' eyesight getting weak in space? Here is what scientists have to say
Produced by Tarun Mishra
Produced by Tarun Mishra
A study published in the IEEE Open Journal of Engineering in Medicine and Biology reveals that prolonged exposure to microgravity aboard the International Space Station (ISS) results in significant changes to astronauts’ eyes and vision. These changes, collectively known as spaceflight-associated neuro-ocular syndrome (SANS), affect at least 70% of astronauts during six- to twelve-month missions.
Researchers analysed data from 13 astronauts with an average age of 48, representing space agencies from the U.S., Europe, Japan, and Canada. They observed a 33% decrease in ocular rigidity, an 11% drop in intraocular pressure, and a 25% reduction in ocular pulse amplitude after missions lasting 157–186 days.
SANS symptoms include reduced eye size, altered focal fields, optic nerve swelling, and retinal folds. Five astronauts were noted to have an increased choroidal thickness exceeding 400 micrometers, regardless of age, gender, or prior space experience.
Sunita Williams, a veteran astronaut, has reported vision issues during her extended stay aboard the ISS. Her case aligns with the study's findings, emphasising the challenges astronauts face during prolonged exposure to microgravity. Williams’ experience raises questions about managing SANS, particularly as missions to Mars and other deep-space destinations are planned.
Researchers attribute the expansion of the choroid to weightlessness-induced changes in blood distribution, leading to increased blood flow to the head and slower venous circulation in the eye. This expansion could stretch the sclera, causing lasting alterations in the eye’s mechanical properties.
While most astronauts’ eyes returned to normal after their ISS missions, the potential for more severe and long-lasting effects during missions longer than 12 months, such as trips to Mars, remains a concern. No preventive or corrective measures currently exist for SANS during extended space travel.
The Maisonneuve-Rosemont research team in Canada, which led the study, awaits additional data from NASA to deepen its understanding of SANS. Identifying biomarkers for SANS could help screen astronauts before missions, reducing the risk of vision complications during long-duration space exploration.
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