Astronauts travel into space, some stay there for a continuous period of days– and come back after completing their mission. But during the long journey, astronauts vision is affected. Researchers say visual problems are related to volume changes in the clear fluid found in the brain and spinal cord. Flight surgeons and scientists at the U.S., space agency, NASA said that astronauts had blurry vision, apart from this they also faced several structural changes. The cause of the impairment is due to the flattening at the back of the eyeballs and inflammation of the head of the optic nerves. The increased pressure of the cerebrospinal fluid in microgravity is the main cause of the flattening at the back of the eyeball.
When a human produces more cerebrospinal fluid, or absorb less, the pressure in the skull increases and there’s nothing that gives way except the eyeball which leads to flattening of the eyeball and thus the change in the vision occurs.
Study lead author, Noam Alperin said, “People initially did not know what to make of it, and by 2010 there was growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to Earth.”
It was found that cerebrospinal (CSF,) fluid which helps in circulating and removing waste material was the main cause of the syndrome. Dr. Alperin who is a professor at University of Miami’s Miller school of Medicine, along with his team found the reason behind the impairment. Dr. Alperin said, “On Earth, the CSF system is built to accommodate these pressure changes but in space, the system is confused by the lack of posture-related pressure changes.”
The astronauts who went for a long duration mission had increased post flight flattening of their eyeballs as compared to the astronauts who had gone for a short duration.
According to Dr. Alperin, NASA is taking various countermeasures to prevent visual imparity and help astronauts in the future.
