By BEC CREW
(Science Alert) A mysterious syndrome
has been impairing astronauts’ vision on the International Space
Station, causing untreatable nearsightedness that lingers for months
even after they’ve returned to Earth.
The problem is so bad that two-thirds of astronauts
report having deteriorated eyesight after spending time in orbit. Now
scientists say they finally have some answers - and it’s not looking
good for our prospects of getting to Mars.
"Nobody’s gone two years with exposure to this, and the concern is
that we’d have loss of vision," Dorit Donoviel from the US National
Space Biomedical Research Institute told The Guardian. "That is catastrophic for an astronaut."
Earlier this year,
NASA reported that something in space has been messing with its
astronauts’ perfect eyesight, causing long-term impairment to their
quality of vision.
Astronaut Scott Kelly, whose exceptional vision was part of the reason
he was selected to be America’s first astronaut to spend a full year in
space, says he's been forced to wear reading glasses since coming home.
John Phillips, who spent time on the International Space Station
(ISS) in 2005, brought his sudden bouts of blurry vision home with him,
and during his post-flight physical, NASA confirmed that his vision had
gone from 20/20 to 20/100 in just six months.
NASA suspected that the condition - called visual impairment inter
cranial pressure syndrome, or VIIP - was caused by the lack of gravity
The hypothesis was that the microgravity of the ISS was building up pressure in astronauts’ heads, causing roughly 2 litres of vascular fluid to shift towards their brains.
They say that pressure was responsible for the flattening of eyeballs and inflaming of optic nerves observed in returned astronauts.
"On Earth, gravity pulls bodily fluids down toward the feet. That
doesn’t happen in space, and it is thought that extra fluid in the skull
increases pressure on the brain and the back of the eye," Shayla Love reported for The Washington Post.
Now, a team from the University of Miami has conducted the first
study to actually test this idea, and found that something else has been
causing vision problems in astronauts.
The researchers compared before and after brain scans from seven
astronauts who had spent many months in the ISS, and compared them to
nine astronauts who had just made short trips to and from the US space
shuttle, which was decommissioned in 2011.
The one big difference between the two was that the long-duration
astronauts had significantly more cerebrospinal fluid (CSF) in their
brains than the short-trip astronauts, and the researchers say this -
not vascular fluid - is the cause of the vision loss...(continued)