The mysterious syndrome impairing astronauts’ sight

[Mr. Man-wai Chang]

Full story:
https://www.washingtonpost.com/national/health-science/the-mysterious-syndrome-impairing-astronauts-eyesight/2016/07/09/f20fb9a6-41f1-11e6-88d0-6adee48be8bc_story.html?utm_term=.fc5aa3550476

Researchers have found that many astronauts who do a six-month mission
in space come back with a condition that causes blurred vision. (Whitney
Shefte/The Washington Post)
By Shayla Love July 9

In 2005, astronaut John Phillips took a break from his work on the
International Space Station and looked out the window at Earth. He was
about halfway through a mission that had begun in April and would end in
October.

When he gazed down at the planet, Earth was blurry. He couldn’t focus on
it clearly. That was strange — his vision had always been 20/20. He
wondered: Was his eyesight getting worse?

“I’m not sure if I reported that to the ground,” he said. “I think I
didn’t. I thought it would be something that would just go away, and fix
itself when I got to Earth.”

It didn’t go away.

During Phillips’s post-flight physical, NASA found that his vision had
gone from 20/20 to 20/100 in six months.

Rigorous testing followed. Phillips got MRIs, retinal scans,
neurological tests and a spinal tap. The tests showed that not only had
his vision changed, but his eyes had changed as well.

The backs of his eyes had gotten flatter, pushing his retinas forward.
He had choroidal folds, which are like stretch marks. His optic nerves
were inflamed.

Phillips’s case became the first widely recognized one of a mysterious
syndrome that affects 80 percent of astronauts on long- ­duration
missions in space. The syndrome could interfere with plans for future
crewed space missions, including any trips to Mars.

[Mr. Man-wai Chang]

Mar 13, 2012 10:46 AM By Christine Hsu

Source:
<http://www.medicaldaily.com/nasa-astronauts-brain-scans-reveal-tissue-and-eye-damage-after-space-flight-239926>

Magnetic resonance imaging of the eyes and brains of NASA astronauts,
who have spent long periods of time in orbit, revealed damage to their
eyeballs and brain tissue, side effects similar to intracranial
hypertension, a condition in which pressure builds within the skull,
according to a new study.

Researchers are worried about their finding because the increased
pressure around the brain can result in visual impairment.

The study, published in the journal Radiology, consisted on 27
astronauts who were either exposed to microgravity or zero gravity for
an average of 108 days while on space shuttle missions or on the
International Space Station, a research facility orbiting the Earth.

The researchers found of the astronauts who had spent more than 30 days
of cumulative time in space, nine of them had expansion of the cerebral
spinal fluid space surrounding the optic nerve, six had flattening of
the rear of the eyeball, four had bulging of the optic nerve, and three
had changes in the pituitary gland, which store hormones that control a
variety of important body functions, and its connection to the brain.

"NASA has placed this problem high on its list of human risks, has
initiated a comprehensive program to study its mechanisms and
implications, and will continue to closely monitor the situation," said
William Tarver, chief of flight medicine clinic at NASA/Johnson Space
Center, in a statement. He also noted that the space agency has begun
noticing changes in the vision in some ISS astronauts, but that the
problems were not fully understood.

Many astronauts returning to Earth find that they cannot focus their
eyes properly after they come home, and some who had once had 20/20
vision suddenly needed glasses for the first time in their lives, NASA
said, according to ABC.

Living in a weightless environment for long periods of time can also
result in bone mineral loss and muscle atrophy as well as dangerous
exposure to the sun’s radiation, and it is because of these health
hazards that stays on the International Space Station are restricted to
six months.

"Microgravity-induced intracranial hypertension represents a
hypothetical risk factor and a potential limitation to long-duration
space travel," said lead author Larry Kramer, professor at The
University of Texas Medical School in a statement released on Tuesday.

Experts said that the latest findings make sense because the human body
is accustomed to gravity, and the heart pumps to keep fluids from
resting in the legs, so in zero-gravity conditions, the body still keeps
pumping the fluids upwards. Many astronauts report stuffiness in the
head, and on short flights spicy Tabasco sauce and horseradish are
reportedly very popular to clear out the sinuses.

"We've known about vision changes on orbit but in some cases we've
actually found that it can be permanent," Peggy Whitson, who has flown
twice on the station and is currently the chief of the astronaut office,
told ABC. "Some of it is reversible. Some people get reverses and they
come back to the same level that they were at pre-flight, and some were
not reversible. We don't know enough yet to understand the mechanisms
for how that happens."

She told the station that while 60 percent of the astronauts exhibited
health problems after having spent more than a month living in space,
the other 40 percent appeared to be immune, and the agency cannot figure
out what protects some but now others.

"The MRI findings revealed various combinations of abnormalities
following both short- and long-term cumulative exposure to microgravity
also seen with idiopathic intracranial hypertension," said lead author
Larry Kramer, professor at The University of Texas Medical School.
"These changes that occur during exposure to microgravity may help
scientists to better understand the mechanisms responsible for
intracranial hypertension in non-space traveling patients."