Here’s some good news for astronauts getting ready for long trips in space. A mysterious condition that has caused blurry vision in most astronauts on long flights has finally been solved and methods to prevent it are being developed.
For over a decade, flight surgeons and researchers at NASA have been puzzled by vision problems found in astronauts after long stints in the International Space Station.
People initially didn't 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.
Noam Alperin, professor of radiology and biomedical engineering of the University of Miami, was selected by NASA to study the problem and his diagnosis and possible preventions and treatment were presented in a paper this week at the annual meeting of the Radiological Society of North America.
While returning astronauts with blurred vision often had structural changes in their eyes such as flattening at the back of their eyeballs and inflammation in their optic nerves, the real cause of the problem was elsewhere. Alperin found that the astronauts experienced changes in the volume of clear cerebrospinal fluid around their brains and spinal cords. On Earth, the fluid cushions and protects both, especially when a person goes from lying to standing. Things are different in zero-gravity, says Alperin. .
In space the system is confused by the lack of the posture-related pressure changes.
His team performed high-resolution MRI scans on astronauts before and immediately after long-duration spaceflights and found the culprit - a condition known as visual impairment intracranial pressure (VIIP). Their bodies created an excessive amount of the fluid in space, causing the astronauts to become temporarily – and sometimes permanently - farsighted.
Unfortunately, the solution isn’t readily apparent. Professor Alperin has received a $600,000 grant from NASA to study the changes in cerebrospinal fluid under weightless conditions.
As with other physical effects it has on astronaut bodies, zero-gravity looks like fun but causes serious problems.