Mysterious syndrome weakens astronauts' eyesight

A dangerous syndrome threatens astronauts' eyesight in a zero gravity environment. How do researchers see this problem?

In 2005, during a coffee break on the International Space Station, astronaut John Phillips looked through the window toward the earth. He has accomplished half of the mission on this ship, starting in April and will end in October.

When looking down on the planet, the Earth has faded. Phillips could not focus on looking at it clearly. Strangely, his vision always reached 20/20 and he wondered: Can my eyesight get worse?

Phillips said: "I'm not sure whether to report on the ground and I didn't. I just thought something was wrong and will definitely recover when I return to earth."

After Phillips's flight, NASA realized his eyesight had dropped from 20/20 to 20/100 in just six months.

Phillips is rigorously tested after MRIs, retinal scans, nerve tests and lumbar spinal stenosis. Tests showed that not only did his eyesight change but his eyes were the same.

John Phillips began to experience visual problems during his time on the International Space Station in 2005, but he did not let anyone know when in space.(Photo: NASA).

The back of the eye becomes flatter, pushing the retina forward, appearing the choroid folds like stretch marks and his optic nerves also inflamed.

Phillips' case has been widely recognized as one of the mysterious syndromes that affects 80% of astronauts performing long-term tasks in space, including trips to Mars.

Intracranial Pressure Syndrome (VIIP) is the name given to explain this. On Earth, gravity pulls the body's liquid down to the feet, which does not happen in space and we know that adding liquid to the skull will increase the pressure on the brain and the back of the eye. VIIP has now been recognized as a common problem and has been explored about and even studied about it.

Theory of fluid accumulating in the skull during space flight has not been tested. Proven methods only measure invasive endoscopic pressure: puncture the lumbar spine or drill a hole into the skull.

On Earth, the most common is spontaneous intracranial hypertension (IIH) and patients in this condition have symptoms of increased head pressure and visual changes. Other conditions also have papillary edema, related to optic nerve swelling.

However, there is no perfect model with astronaut disorders. IIH comes with a variety of symptoms such as nausea, dizziness and severe headaches, but VIIP does not have these symptoms. Treatment for epilepsy edema, neural optics is ineffective with VIIP.

Many studies are being done to find ways to assess brain health on Earth and in space. The device developed uses sound waves and radio waves to try to measure the brain at different points: the skull, ears and eyes.

Eric Bershad, an intensive neuroscientist at Baylor College of Medicine, said: "So far, no non-invasive technology is accurate enough to replace invasive measuring devices, but in a few years. I think there will be ".

Ross Ethier, a biomedical engineer at the Georgia Institute of Technology, is looking for a potential mechanical solution: a device that can pull body fluids down to the feet in space. This device is quite annoying and annoying, so you need to know how long the astronaut wears it during the day, two or three hours?

Astronaut Michael Barratt, a former director of NASA's human research program, also found his eyesight deteriorated after six months of performing a mission on a spaceship. Both he and his partner Bob Thirsk received medical training.

Barratt said: "We are thinking about ourselves and wondering if we are physicists or not, so we do eye exams for each other." And they both see signs of a swollen eye nerve. After NASA sent more imaging devices, they found VIIP syndrome - flattened eye shape and visual disc swelling.

Barratt thinks that solving the problems of VIIP needs to test the intracranial pressure in space , even invasive procedures. One option is to implant a pre-flight intracellular probe to measure pressure at various points in the brain throughout the cosmic journey.

Barratt found a similarity with the thorny problem that happened in 1990 when the pressure in the heart was unreasonably affected by space flights. NASA also conducted invasive testing, inserting catheters into the hearts of astronauts.

"We were reckless purely for science and now we face a similarly risky decision. But in this case, this is not a science project but a matter of Medical, affecting those who are performing space missions , " Barratt said.

Photo of the astronaut's eyes before and after.(Photo: Courtesy North American Neuro-Ophthalmology Society).

The top risk is still exposure to radiation . According to the radioactivity meter on the Mars Curiosity Rover Mars probe, a person is able to reach at least 0.66ieverts to reach Mars and return. This level is equivalent to a full-body CT scan of 5-6 days, increasing the risk of cancer and other diseases.

Before humans could explore Mars from 6 to 9 months in 2030, researchers agreed that VIIP syndrome should be seen more deeply. VIIP can be the first sign of threats to the human body in a zero gravity environment. Barratt added: "We are seeing visual and neurological expressions and I'm sure there will be more effects."

Richard Williams, health and medical director at NASA, agrees that what we don't know about the VIIP is actually the biggest threat. Ironically, one of the ways to deepen the problem is to spend a lot of time in a zero gravity environment."The longer we stay in space, the more we learn , " Williams said.

It took 6 months to return to Earth, but Phillips' vision improved from 20/100 to 20/50 and remained so until 11 years later. You cannot pass the eye DMV test without glasses.

However, he and the other astronauts all said that they did not exchange time in space to regain lost vision. Michael Lopez-Alegria, the astronaut who holds the record for a space walk in the US, called zero gravity as magic. Currently he is wearing contact lenses with correction +2.5.

Phillips now considers himself a 65-year-old man living with glasses. He was once considered the best visionary boy, who saw the first traffic sign in the car."It was far away at that time," Phillips said wryly.