In response to a brand new research, 70% of astronauts who’ve spent between six and 12 months aboard the Worldwide House Station (ISS) skilled important modifications to their imaginative and prescient on account of a situation known as “spaceflight-associated neuroocular syndrome,” or SANS.
SANS entails signs like swelling of the optic nerve, flattening in the back of the attention and common modifications in imaginative and prescient. It happens when fluids within the physique shift whereas uncovered to microgravity situations, thereby placing strain on the eyes.
The excellent news is that these modifications usually reverse after astronauts return to Earth, and in some circumstances, sporting corrective eyeglasses is sufficient to handle the signs whereas they’re occurring. Nonetheless, the long-term results of extended publicity to microgravity stay unsure, posing a big problem for house businesses that goal to see longer missions, similar to these to Mars, develop into a actuality.
With no confirmed preventive or remedy methods at present in place, discovering options is a high precedence for making certain astronaut well being on prolonged space journeys.
House businesses have been conscious of SANS because the early 2000s, and researchers are actively attempting to determine the precise dynamics of the situation and cement a possible answer. One of many earliest research regarding this subject, carried out on Russian cosmonauts who had participated in long-duration missions aboard the Mir house station, reported comparable ocular modifications — although the situation had not but been recognized as SANS. NASA formally acknowledged and named the syndrome in 2011, defining it as “distinct ocular, neurological and neuroimaging findings.” The first suspected reason behind SANS is the shift of bodily fluids towards the pinnacle in microgravity, resulting in elevated strain on the mind and eyes. Nonetheless, the precise mechanisms stay below investigation.
“A number of theories have been recommended similar to hemodynamic fluid shift, publicity to CO2 and train in microgravity situations,” the science crew, led by Santiago Costantino on the Université de Montréal, wrote within the new research. “Understanding the modifications within the mechanical properties of ocular tissue couldn’t solely shed new mild into the illness’s pathophysiology however probably help in each the identification of people at a better danger of growing irreversible eye harm and within the improvement of countermeasures in opposition to SANS.”
Of their research, Costantino and his crew analyzed information from 13 astronauts who spent 5 to 6 months aboard the International Space Station. The group, with a mean age of 48, included astronauts from the U.S., Europe, Japan, and Canada. Thirty one % had been girls, and eight had been on their first mission.
The researchers examined three key eye measurements earlier than and after spaceflight: ocular rigidity, which displays the stiffness of eye tissue, intraocular strain, the fluid strain inside the attention, and ocular pulse amplitude, the variation in eye strain with every heartbeat.
They measured ocular rigidity utilizing a particular imaging method to get clearer footage of the choroid, which is the layer of blood vessels within the eye. For the opposite two measurements, they used tonometry, a typical software to examine the strain inside the attention.
The research revealed important modifications within the biomechanical properties of the astronauts’ eyes, together with a 33% drop in ocular rigidity, an 11% lower in intraocular strain, and a 25% discount in ocular pulse amplitude. These shifts had been linked to signs similar to a lower in eye measurement, modifications in focal discipline, and, in some circumstances, swelling of the optic nerve and retinal folds.
Moreover, the researchers discovered that 5 astronauts had a choroidal thickness exceeding 400 micrometers, which is larger than regular. Usually, the typical choroidal thickness in wholesome adults is between 200 and 300 micrometers. Curiously, this variation gave the impression to be unrelated to age, gender, or prior spaceflight expertise.
Researchers and house businesses are engaged on countermeasures and coverings, together with pharmaceutical interventions, diet and instruments that apply detrimental strain to the decrease physique to assist draw fluids away from the pinnacle.
Research like this, which enhance our understanding of the syndrome’s results on the physique, will assist speed up the event of options.
“The noticed modifications within the mechanical properties of the attention may function biomarkers to foretell the event of SANS,” Costantino mentioned in a statement. “This might assist establish at-risk astronauts earlier than they develop severe eye issues throughout long-duration missions.”
