Produced by: Manoj Kumar
Astronauts aboard the ISS experience eye changes due to spaceflight-associated neuro-ocular syndrome (SANS), with 70% affected during missions lasting six to 12 months, according to a study led by Santiago Costantino.
Credit : NASA
In microgravity, the vascular layer of the eye (choroid) expands, likely due to altered blood flow and slowed venous circulation in the head, resulting in increased choroidal thickness in some astronauts.
Credit : NASA
NASA data revealed a 33% drop in ocular rigidity, an 11% decrease in intraocular pressure, and a 25% reduction in ocular pulse amplitude, causing changes in eye shape and optic nerve stress.
Credit : NASA
Weightlessness leads to blood redistribution, causing a “water-hammer effect” that may remodel eye tissues by generating mechanical shocks from fluctuating blood-flow pressure.
While 80% of astronauts showed at least one symptom, including optic nerve swelling and retinal folds, these changes typically reverted to normal after returning to Earth, often corrected with eyeglasses.
The effects of microgravity on eye health over longer missions, such as a trip to Mars, remain unknown. Researchers warn that prolonged exposure could pose greater risks without current preventative solutions.
Credit : NASA
Costantino’s team suggests using observed eye changes, like decreased ocular rigidity, as biomarkers to identify astronauts at risk of SANS before long-duration missions.
Ocular rigidity and other parameters were measured with advanced tools, including optical coherence tomography and tonometry, offering precise insights into eye changes caused by space travel.
The Maisonneuve-Rosemont research team, in collaboration with NASA, awaits additional data to deepen understanding and develop solutions for long-term spaceflight eye health challenges.