In his logbook, Thomas Pesquet notes that his eyesight is declining. The accumulation of cerebrospinal fluid in the skull distorts the eye sockets during a long mission.
From the International Space Station (ISS), Thomas Pesquet takes full view. And it makes Internet users benefit from it. On his twitter account, the French astronaut regularly publishes breathtaking photos of our planet. A pleasure for the eyes… which is not without consequences.
For several years, surgeons and scientists from the American space agency (NASA) have observed a strange phenomenon among space travelers. After a long mission, their vision deteriorates. In question, microgravity. This is what radiologists from the University of Miami (United States) explained during the Congress of the North American Society of Radiology (RSNA) which was held from November 21 to December 2 in Chicago (United States). ).
The flatter eyeball
Two in three astronauts suffer from visual disturbances upon their return from the ISS. Thomas Pesquet is no exception. “I who have excellent eyesight on Earth, I already feel that it is decreasing in the ISS”, he writes this December 27 in his logbook. The 38-year-old attributed this to an increased blood flow to his skull. “It creates pressure that affects the eyes,” he explains. This does not prevent him from immortalizing dazzling landscapes.
Looks like an artist had fun with a brush in the desert, to our delight ????https://t.co/csNtQOQqrc #Proxima pic.twitter.com/SjbreeSSeX
– Thomas Pesquet (@Thom_astro) Dec. 26, 2016
Sunny australia for # Christmas2016 : as a metropolitan Frenchman, the idea of spending the holidays in the middle of summer has always intrigued me! ???????? pic.twitter.com/xsRieoevv2
– Thomas Pesquet (@Thom_astro) December 25, 2016
Night show: the light of the moon is reflected on the snow and comes to dance with the radiance of the cities… Here Turin, Milan and… Lyon;) ?????????? pic.twitter.com/bcEkjTxQQQ
– Thomas Pesquet (@Thom_astro) December 24, 2016
Microgravity changes the distribution of fluids in the body, and the upper body receives more blood than on earth. The blood flow may therefore be taken into account, but researchers in Florida highlight another phenomenon: intracranial pressure. They gave 7 astronauts MRI scans before they left for the ISS. A second round of examinations was carried out upon their return. These results were compared to those of 9 cosmonauts who went on a short mission. The difference is very clear.
A long journey in space induces structural changes around the eye. The eyeball flattens, the optic nerve is more inflamed. Many astronauts “will have to wear glasses for life, whereas they did not wear them before, recently underlined Jean-François Clervoy of the European Space Agency. This comes from a deformation of the geometry of the eyeball.
The pressure is building
In fact, more cerebrospinal fluid accumulates in the skull than it needs to. This fluid, found in the brain and spine, accompanies violent changes in pressure in the body, when getting up quickly for example. “On Earth, CSF is designed to adapt to these changes in pressure; but in space, the system is disturbed by the absence of pressure changes linked to posture, ”summarizes Noah Alperin, who presented the study. Microgravity, at work in the ISS, does not change anything.
It is the pressure of the CSF that would cause the deformities around the eye. And these are not always reversible, reminds Le Figaro : “In 2007, an astronaut lost more than 30% of his visual field in one eye”, confides to the daily Bernard Comet, former doctor of the French astronauts from 1983 to 2001. Most often, however, this manifests itself by hyperopia , which interferes with far vision.
American researchers stress that it is crucial to find the precise cause of these changes. This will allow NASA and other space agencies to develop suitable countermeasures, and thus protect teams on long-term missions.
.
