Astronauts returning from extended space missions are reported to experience significant changes in eye health, linked to prolonged exposure to microgravity. Researchers have identified that the altered blood flow and pressure conditions in space can lead to vision problems. These changes are primarily associated with a condition termed spaceflight-associated neuro-ocular syndrome (SANS), affecting around 70 percent of astronauts during six- to twelve-month stays on the International Space Station (ISS). This raises potential challenges for longer missions, such as a journey to Mars.
Study Identifies Key Ocular Changes
According to a study published in the IEEE Open Journal of Engineering in Medicine and Biology, three critical ocular parameters were analysed: ocular rigidity, intraocular pressure, and ocular pulse amplitude. Measurements were conducted on data from 13 astronauts, whose missions spanned 157 to 186 days. The researchers observed a 33 percent reduction in ocular rigidity, an 11 percent decrease in intraocular pressure, and a 25 percent decline in ocular pulse amplitude. These findings indicate biomechanical changes in the eye, accompanied by symptoms such as reduced eye size, optic nerve swelling, and retinal folds.
Potential Long-Term Effects
Dr Santiago Costantino, an ophthalmologist at Université de Montréal, highlighted to phys.org that microgravity alters blood flow and venous circulation in the eye, potentially leading to structural changes in the sclera and choroid. The observed changes could persist, raising concerns about the impact on missions exceeding one year. While most astronauts studied returned to normal vision after their missions, corrective lenses were sometimes necessary during recovery.
Mars Missions Pose New Risks
Experts remain cautious about the unknown implications of prolonged exposure to microgravity during extended missions like those to Mars. The research team emphasised that additional studies and preventive strategies are essential to address these risks. The findings serve as early indicators to identify astronauts at risk, paving the way for more targeted solutions to ensure the safety of space exploration’s next frontier.