March 13, 2012

Astronauts Experience Eyeball Deformation In Space

A new study has found that astronauts' eyeballs have become deformed after spending a long time in space.

The researchers said that flattening at the back of the astronauts' eyes may be caused by increased pressure of cerebrospinal fluid in microgravity.

Doctors examined 27 astronauts who had flown long-duration missions with NASA and found a pattern of deformities in their eyeballs, optical nerves and pituitary glands that remains unexplained.

The problems are similar to those caused by a rare medical condition that occurs when pressure inside the skull rises and presses on the brain and the back of the eyes.  This medical condition is known as intracranial hypertension.

The results of the study is bad news to space agencies wanting to send astronauts on long-duration missions, like sending man to mars.

Astronauts who had flown on space shuttle and International Space Station missions had been reporting changes to their eyesight, with some seeing worse and others seeing better than they had before.

Brain scans revealed that seven of the 27 astronauts had a flattening of the back of one or both eyes.

Larry Kramer, who led the study at the University of Texas Health Science Center in Houston, said the impact on astronauts' eyesight may limit man expanding its reaches into deep space.

"There are major political, social and individual ramifications relative to this thought alone," Dr Kramer wrote in the journal Radiology.

"Consider the possible impact on proposed manned missions to Mars or even the concept of space tourism. Can risks be eventually mitigated? Can abnormalities detected be completely reversed? The next step is confirming the findings, defining causation and working towards a solution based on solid evidence."

Kramer said it could take space agencies months or years to fully understand the effect the astronauts have seen.

"The question now is, do these changes plateau after six months, or will longer-duration missions mean there will be even more astronauts experiencing more severe abnormalities?" Dr Kramer said.

Spending time in space causes dramatic shifts in body fluid, but potential changes in the distribution of brain fluid are a new concern.

Weightless condition causes body fluid to rise up, giving astronauts puffed-up faces and scrawny legs.

Some astronauts had returned to Earth after long-duration missions and have been too weak to stand up at first.

Another side effect that some might see as positive one is that spending time in space reduces the wrinkles in an astronauts' face, making them look years younger in orbit.

So far, symptoms astronauts have reported have died down within weeks or months of coming back down to Earth.

William Tarver, head of flight medicine at NASA's Johnson Space Centrer in Houston, said no astronauts have ruled out of flying after the findings.

"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," he said.


On the Net: