This Is Why Astronauts Develop Eye Problems in Space

Monday, 28 November 2016 - 2:45PM
Space
Science News
Monday, 28 November 2016 - 2:45PM
This Is Why Astronauts Develop Eye Problems in Space
Over the last decade, flight surgeons and scientists at NASA have seen a pattern of vision problems arising in astronauts on long-duration space missions. The syndrome, called visual impairment intracranial pressure (VIIP), has been reported in nearly two-thirds of space explorers after returning from missions aboard the ISS. In addition to blurry vision, the astronauts exhibited flattening at the back of their eyeballs and inflammation at the head of the optic nerve. 

Now, a team of researchers at the University of Miami has discovered that problem is associated with spinal fluid, or more specifically, with volume changes in the cerebrospinal fluid (CSF) found around the brain and the spinal cord. On Earth, the CSF system can accommodate sudden changes in pressure, like when you stand up suddenly after lying down. But in space, the system is confused by the lack of posture-related pressure changes, explained lead study author Noam Alperin. 

"People initially didn't know what to make of it, and by 2010 there was a growing concern as it became apparent that some of the astronauts had severe structural changes that were not fully reversible upon return to Earth," Alperin said a recent conference (via The BBC). 

Prior to the current study, scientists thought the problem has to do with a shift of vascular fluids towards the upper body in exposure to microgravity. 

But brain scans taken of the astronauts both before and after long-duration space missions revealed the flattening of the eyeballs and increased optic nerve protrusion. More importantly, the astronauts also exhibited significantly greater post-flight increases in CSF volume in the area around the optic nerves and the cavities where CSF is produced than their short flight mission counterparts. 

Though the sample size is small - just nine astronauts - and the results have not yet appeared in a peer-reviewed journal, Professor Alperin is confident that the research points to a "primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome."

Alperin has received a $600,000 grant from NASA to study the condition, and, armed with this new information, scientists and doctors back on Earth will be better able to find a way to prevent this kind of permanent eye damage, and treat the condition when the astronauts arrive back on Earth.
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