56 minutes in the pastWriter: Samira Siddiqui
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Do you know that house journey might change an astronaut’s eyesight? For astronauts spending months in house, imaginative and prescient adjustments are an actual well being concern. NASA says round 70% of astronauts aboard the Worldwide House Station expertise swelling in the back of their eyes, a situation linked to long-duration spaceflight known as Spaceflight-Related Neuro-Ocular Syndrome (SANS).
That’s the reason NASA and different house businesses are finding out SANS intently earlier than people start spending longer durations across the Moon and finally journey to Mars.
What precisely is SANS?
Picture credit score: Nature
Spaceflight-Related Neuro-Ocular Syndrome, or SANS, is just not merely a case of astronauts needing stronger glasses. It’s a assortment of adjustments involving the eyes, optic nerves and mind that may happen after spending a very long time in microgravity. NASA says the situation can embody swelling of the optic nerve, folds within the retina, flattening of the again of the eyeball and different structural adjustments. The precise motive why SANS develops remains to be not utterly understood. Nevertheless, scientists consider that the motion of physique fluids in microgravity performs an essential function.
Picture credit score: NASA weblog
On Earth, gravity continuously pulls blood and different physique fluids in direction of the decrease components of the physique.
In house, that gravitational pull is basically absent.
In consequence, fluids that will usually stay decrease within the physique can shift in direction of the top and higher physique. This may enhance stress across the mind and eyes and will contribute to adjustments within the optic nerve and the form of the eyeball.
Circumstances the place astronauts skilled SANS NASA has documented astronauts experiencing adjustments of their imaginative and prescient throughout lengthy stays aboard the ISS. In a single case, astronaut Michael Barratt and Canadian astronaut Robert Thirsk developed problem studying procedures throughout a six-month mission and wanted stronger glasses. Their signs led researchers to research the attention adjustments related to long-duration spaceflight.
Astronaut Michael Barratt
In one other notable instance is NASA astronaut John Phillips, who started his 2005 mission with regular 20/20 imaginative and prescient. After spending about six months aboard the ISS, his imaginative and prescient had dropped to twenty/100, exhibiting how considerably long-duration spaceflight can have an effect on eyesight.
NASA astronaut John Phillips, who started his 2005 mission with regular 20/20 imaginative and prescient. Picture credit score: AGEI
Some astronauts subsequently develop what scientists describe as a farsighted shift, making close-up duties comparable to studying tougher. ESA astronaut Sophie Adenot has additionally described common imaginative and prescient checks in orbit as a result of microgravity could cause adjustments in visible sharpness and farsightedness.
Additionally learn: NASA invites ISRO to join moon base mission: Both India and US to explore greater scientific data sharing under Artemis Accords Does SANS imply astronauts go blind?
This is a crucial distinction. The assertion that astronauts “lose 70% of their eyesight” is just not what NASA says. The 70% determine refers to astronauts experiencing swelling in the back of their eyes, not a 70% lack of imaginative and prescient.
The results additionally differ from astronaut to astronaut.
Some expertise comparatively delicate adjustments, whereas others can develop extra important adjustments of their imaginative and prescient and eye construction. NASA says the long-term well being penalties are nonetheless being investigated.
Nevertheless, researchers are involved that sure structural adjustments might persist, significantly after longer missions. What about Indian astronauts?
India’s human-spaceflight programme makes this query significantly related.
Indian astronaut Shubhanshu Shukla turned the primary Indian to go to the Worldwide House Station throughout the Axiom-4 mission in 2025. NASA recognized him as an ISRO astronaut and pilot of the mission.
Indian astronaut Shubhanshu Shukla turned the primary Indian to go to the ISS throughout the 2025 Axiom-4 mission.
Nevertheless, there’s at the moment no public proof from ISRO or NASA exhibiting that Shukla developed SANS or suffered everlasting imaginative and prescient injury throughout that mission.
This is a crucial distinction: astronauts can expertise regular physiological adjustments in microgravity with out essentially growing clinically important SANS. Why are Mars missions a much bigger concern?
Picture credit score: NASA
A mission to Mars is much more difficult than a keep on the ISS as a result of astronauts will spend for much longer away from Earth. NASA says the chance of SANS will increase with longer house missions, elevating considerations about astronauts’ imaginative and prescient throughout deep-space journey. With communication delays additionally rising, astronauts may have to watch their eye well being themselves moderately than depend on medical doctors on Earth.
NASA already checks astronauts’ eyes in house
Astronauts on the ISS recurrently bear eye checks utilizing Optical Coherence Tomography (OCT), which captures detailed photos of the again of the attention to detect adjustments. Nevertheless, present OCT techniques are cumbersome and infrequently require assist from specialists on Earth, making them much less sensible for future deep-space missions.
Siloton: An eye fixed scanner sufficiently small for house
Siloton Picture credit score: Wired
That is the place British health-tech firm Siloton is available in. The corporate is growing a a lot smaller OCT-based eye-scanning system utilizing photonic-chip expertise.
Conventional OCT machines use a big assortment of optical elements comparable to lenses, mirrors and fibre optics. Siloton says its expertise can compress a lot of this method onto a photonic chip smaller than a coin.
The corporate has already used its expertise to seize photos of human retinas, and its transportable system is being developed to be used outdoors conventional hospitals and specialist eye clinics.
May SANS trigger everlasting eye injury?
This is likely one of the largest unanswered questions. NASA remains to be finding out the long-term results of SANS. Whereas some eye adjustments might enhance after astronauts return to Earth, scientists are involved about longer missions. Early detection by common eye scans might assist establish adjustments earlier than they considerably have an effect on an astronaut’s imaginative and prescient or means to work.
Additionally learn: AI traffic may outpace humans by 1,000 times, predicts Musk: Non-human traffic overtook human-generated traffic in May 2026, reports Cloudflare Does each astronaut get SANS?
NASA astronaut Karen Nyberg makes use of a fundoscope in orbit to {photograph} her retina, serving to scientists examine how spaceflight impacts the eyes. Picture Credit score: NASA
NASA says astronauts can expertise totally different ranges of eye adjustments. Some have delicate results, whereas others expertise clinically important adjustments. Scientists are nonetheless making an attempt to grasp why. Components such because the size of the mission, particular person variations, fluid motion, stress adjustments, and different physiological components might all play a job. That is additionally why gathering extra information is essential.
Why eye well being issues for future house missions
Astronauts are not being ready just for brief journeys into orbit. House businesses are planning missions across the Moon and are finding out what it will take to ship people to Mars. However getting astronauts there safely means fixing issues that will not seem throughout shorter missions.
SANS is one in every of them. An astronaut who develops weaker imaginative and prescient on Earth can merely go to an eye fixed physician and get new glasses. An astronaut travelling to Mars doesn’t have that luxuryhat is why a tiny eye scanner might change into extra than simply one other piece of medical tools.
As house missions change into longer, defending astronauts’ eyesight might change into simply as essential as defending their bones, muscle tissue and brains.
