How is space travel making astronauts blind? Scientists uncover alarming eye risks from prolonged exposure in space

Space travel affects the human body in unexpected ways. Scientists now highlight a growing concern—eye health. A study from the Université de Montréal reveals that 70% of astronauts experience vision changes. This condition, called spaceflight-associated neuro-ocular syndrome (SANS), poses risks for deep-space missions.

Microgravity shifts bodily fluids upwards, affecting eye pressure. Researchers examined 13 astronauts who spent months on the ISS. Their findings show:

• Ocular rigidity decreased by 33%, making eyes more fragile.


• Intraocular pressure dropped by 11%, altering fluid circulation.


• Ocular pulse amplitude reduced by 25%, affecting blood flow.

These changes can cause blurred vision and optic nerve swelling. Some astronauts even require new prescriptions after space missions.

Can Vision Recover?

The effects of SANS seem to be temporary. Most astronauts regain normal vision after returning to Earth. Around 80% of those studied showed symptoms, but corrective lenses helped.

However, deep-space travel could make SANS worse. NASA and other agencies are working to find solutions. Scientists suggest:

• Wearable devices to regulate pressure inside the head.


• Medications to prevent swelling and fluid buildup.


• Artificial gravity in spacecraft to simulate Earth-like conditions.


• Real-time eye tests to monitor astronauts' vision in space.

Preparing for Future Space Missions

Researchers at Maisonneuve-Rosemont Hospital in Canada are working with NASA. They aim to develop countermeasures for SANS before Mars missions begin. If untreated, these vision problems could impact astronauts' safety and mission success. Understanding and preventing SANS is now a top priority for space exploration.