The Artemis program that will take humans back to the moon and beyond has everyone gazing up at the stars again. We’re well on our way to becoming an interstellar — or at least an intersolar — species, but we still have one challenge to face. What effect does living in microgravity for long periods have on the human body, and more specifically, on the human eye? Let’s take a closer look at how an astronaut’s eyes change in space, and what we will need to do in the future to prevent eye problems during deep space missions.
For the moment, anyone who leaves the Earth’s atmosphere will be living in zero or microgravity environments. NASA’s Twin Study recently took a closer look at what happens to the body after an extended stay in space. Astronaut Scott Kelly lived on the International Space Station for almost a year, and his twin brother Mark remained behind on Earth as a control subject.
Some things stayed the same — like the flu vaccine Scott received before he went into space, which worked just as well when he got home as it did when he flew up to the space station — but other things changed dramatically. Most of these changes, like the lengthening of Scott’s telomeres and the changes in gene expression, returned to normal once he came home. One thing that puzzled scientists, however, was the perpetual vision problems Scott complained of during his extended mission.
Scott Kelly isn’t the only astronaut to experience eyesight problems during his mission. About a third of those on missions shorter than two weeks and 60% of those on long-term missions have reported similar issues.
The problem is in our makeup — specifically, the fact that the human body is mostly water. When you’re here on Earth, gravity pulls the fluids in your body down toward your feet. Without gravity, those fluids move upward, toward your head. The extra fluid in the blood vessels around the eye causes increased intraocular pressure, which results in vision problems. The longer you stay in space, the worse your eyesight becomes.
It’s hard to fly a spacecraft if you can’t see where you’re going, but glasses aren’t going to fix this problem. The solution, though, is closer to home than you might believe.
Gravity is the solution to the eyesight problems astronauts are experiencing. In 2018, NASA sent a group of mice to the JAXA Kibo facility on the International Space Station. Half of them remained floating in microgravity with the astronauts, while the other half spent their time in a rotating centrifuge that generated roughly 1G — Earth-standard gravity.
The study found the mice living in microgravity experienced more cell death in their retinal vascular cells than those who lived in the centrifuge, experiencing humanity’s first attempt at artificial gravity. For long-term zero-gravity missions, artificial gravity will become a necessity to prevent astronauts from experiencing the damaging effects of traveling so far from home.
Here on Earth, though, you can protect your eyes by getting more lutein esters in your diet. These are a type of carotenoid which helps protect your eyes from UV light, and even from the damage from blue-light electronics. You can find lutein esters in everything from kale and collard greens to papaya, broccoli and eggs.
Space travel is no longer something solely in the realm of science fiction stories. In the next decade, if everything goes according to plan, we’ll have a permanent human presence on the moon and be on our way to Mars. Overcoming the challenges of living in microgravity is just one part of the equation, but it is a significant one. As it stands, humans can’t survive in a zero-gravity environment indefinitely, so artificial gravity should be the next technological advancement on our agenda.