Microgravity, the state of near-weightlessness in space, profoundly impacts the human body, especially the eyes and vision. A recent study by researchers at the Université de Montréal revealed that over 70% of astronauts on the International Space Station (ISS) experience changes linked to spaceflight-associated neuro-ocular syndrome (SANS).

Impact of Microgravity on Eyes

Dr. Santiago Costantino, an ophthalmologist at the Université de Montréal, led a team that analyzed data from 13 astronauts who spent between 157 to 186 days on the ISS. The diverse group, spanning various age, nationality, and gender, provided comprehensive information for the study.

Astronauts’ Eyes Change Due to Microgravity

The researchers focused on three critical ocular parameters: ocular rigidity, intraocular pressure, and ocular pulse amplitude. Using optical coherence tomography and tonometry, they found that astronauts experienced a 33% reduction in ocular rigidity, an 11% drop in intraocular pressure, and a 25% decrease in ocular pulse amplitude.

These physiological changes were accompanied by vision issues such as altered focal fields, reduced eye size, and in some cases, optic nerve edema and retinal folds.

The Role of Weightlessness

The root cause of these changes, according to Dr. Costantino, lies in weightlessness. It alters blood distribution, boosting blood flow to the head and reducing venous circulation in the eye. This change is likely responsible for the expansion of the choroid layer, which nourishes the retina.

The Journey Back to Normal

Fortunately, these changes are typically not permanent. Most astronauts’ eyes return to their pre-flight state upon returning to Earth. In many cases, wearing corrective eyeglasses was sufficient to address the symptoms developed during their space mission.

However, the potential risks of long-duration space missions, such as a journey to Mars, warrant caution.

Prolonged Microgravity and Eye Health

The effects of extended exposure to microgravity on eye health are still not fully understood. No preventative or palliative measures currently exist.

Researchers are eagerly awaiting more data from NASA to advance their understanding and develop solutions.

“The observed changes in the mechanical properties of the eye could serve as biomarkers to predict the development of SANS,” said Dr. Costantino.

Such biomarkers could help identify astronauts at risk before they experience severe eye problems.

Preparing for the Mars Challenge

With missions to Mars becoming a reality, this research is crucial. A mission to Mars could last up to three years, a significant increase from the six to twelve months currently spent on the ISS.

Researchers are exploring various strategies to mitigate these risks, including wearable devices to regulate intracranial pressure and techniques simulating Earth-like gravitational forces.

Advancements in technological and pharmaceutical solutions targeting choroidal expansion and venous circulation in the eye could offer new preventive measures.

Real-time monitoring tools are also being developed to help astronauts and mission control teams identify early signs of SANS.

Protecting Astronauts’ Well-Being

Enhanced imaging technologies and portable devices could facilitate early intervention, improving astronaut health and mission success.

Collaboration between researchers, space agencies, and medical professionals will be essential in ensuring long-term astronaut well-being during space missions.

Dr. Costantino and his team’s work represents a significant step forward in safeguarding astronaut health and preparing for humanity’s ambitious journey to Mars and beyond.

The full study was published in the journal Open Journal of Engineering in Medicine and Biology.