Our spinal cord and brain are filled with Cerebrospinal fluid, which is constantly pulled down by gravity. In space, this fluid gets displaced, which can potentially lead to visual impairment.
Being in outer space may sound cool, but are you prepared to lose your vision during your trip to the void? It has been discovered that the negative implications of space exploration don’t just end at diminished bone and muscle mass; it also extends to deteriorated eyesight, and in the most extreme scenarios, permanent blindness.Imagine being on a mission to Mars and suddenly finding yourself unable to read the ship’s instruction manual. Sounds pretty scary, right?
Nearly two-thirds of astronauts have reported deteriorated eyesight following their time in space. Is this a consequence of some supernatural force? Are aliens secretly stealing their eyesight? Or is space just so beautiful that it makes you blind?
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The Story of John Philips
In 2005, astronaut John Phillips took a break from his work on the International Space Station and looked out the window at Earth far below. When he gazed down at the planet, however, Earth was blurry. That was strange, as 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 get to Earth.”
However, it didn’t go away.
During Phillips’s post-flight physical check-up, NASA found that his vision had gone from 20/20 to 20/100 in only six months. Rigorous testing followed, as that is far more rapid than visual acuity typically changes in an individual.
The tests showed that not only had his vision changed, but the physical structure of his eyes had changed! The structure of the back of his eye had been compressed, which pushed his retinas forward. For those who are unfamiliar, retinas are the innermost light-sensitive layers of the eye. Furthermore, his optic nerves were inflamed and he had choroidal folds in his eyes, which are something akin to stretch marks.
Identified by several researchers, scientists and doctors across the globe, Phillips became the first widely recognized case of this perplexing syndrome, which is now known to strike about 80% of astronauts on long-duration missions in space.
The Gravity of the Situation
On Earth, a special force called gravity keeps us bound to the planet. Gravity loves Earth and everything present on it, so if you jump it’s bound to pull you back. It provides weight to physical objects and pulls them towards the center of the planet. Apart from just pulling things downwards, it also pulls the things present inside things downwards.
For example, along with keeping you on the ground, it also enables your bodily fluids to stay grounded!
As a result, at any single given point—excluding certain exceptions—there is never too much fluid present within your brain.
One of these well-regulated fluids is a unique fluid called cerebrospinal fluid (CSF). By the name alone, can you guess where it lives? It lives in two of the most important neighborhoods within your body—the spinal cord and the brain!
The Benefits of Staying Grounded
This critical fluid is truly a master of multitasking. Under normal circumstances, this fluid acts as a cushion for your brain and spinal cord; it also acts as a wholesaler, distributing nutrition around your body, and it loves to be clean, so it constantly gets rid of waste. It also has an extremely adaptable personality, so it can easily adjust to changes in pressure that your body experiences when you transition from sitting down to standing up!
However, in the zero gravity environment of space, this foundational fluid begins to falter.
“On Earth, the cerebrospinal fluid (CSF) system is built to accommodate these pressure changes, but in space, the system is confused by the lack of posture-related pressure change,” says Noam Alperin, a radiologist and biomedical engineer.
Based on the brain MRI scans that were taken of 16 astronauts, it has been found that long-duration astronauts have far higher CSF pooling around their optic nerves, in the part of the skull that holds the eye. They also have significantly more CSF accumulating in the cavities of their brain where this fluid is produced.
A considerable difference exists between those astronauts who travel for long durations in space and those who travel for short durations. Long-duration travelers have significantly more CSF in their brains than short-duration travelers, and researchers state that this is what causes their decrease in vision.
What’s in a name?
Visual Impairment Intracranial Pressure syndrome (VIIP) is the name of this rare syndrome. On Earth, gravity pulls bodily fluids down toward the feet, but that doesn’t happen in space, due to its microgravity environment. It is believed that this extra fluid in the skull increases pressure on the brain and on the back of the eyes.
VIIP has now been recognized as a widespread problem for astronauts, and there has been a great deal of effort made to understand its cause and its nature.
We have a serious problem on our hands. Very few astronauts have spent more than a full year in space, but astronauts are facing at least 18 months in space to get to and from Mars. Furthermore, that’s the timeframe if they fly home immediately after arriving. If we want to think about colonization or extended stays on Mars, we will have to consider blindness as a potential complication.
As of now, there are no solutions for how to treat or prevent the fluid build-up in space, nor the brain damage that is also expected to result from long-duration spaceflights.
Elon Musk’s warning that the first Martian colonists should be “prepared to die” seems more prophetic than ever!