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Poor eyesight is a barrier for long-term space missions. So what causes it?

By Natasha O’Neill, Writer

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    Toronto, Ontario (CTV Network) — When astronauts are in space for long periods of time, the impact of no gravity can weigh on their bodies, including their eyes.

Often when they return to Earth, their vision is worse than before, which can sometimes be irreversible. This can cause them issues not just in the long term, but also for completing tasks in space.

A recent study suggests that poor eyesight is one of the key barriers for humans on long-duration space explorations, including the Artemis mission to eventually send humans to Mars, but new technology like virtual reality (VR) and artificial intelligence (AI) could help test astronauts’ eyesight while in space and come up with solutions to the problem.

The study’s authors, Ethan Waisberg, a Canadian and academic foundation doctor at Cambridge University, and Richard Ong, a resident physician in ophthalmology at the University of Michigan, have introduced a pair of VR goggles to conduct eye tests and are optimizing AI technology to better understand the experiences of astronauts.

Ong said they hope to find the root cause of spaceflight associated neuro-ocular syndrome (SANS), which is the umbrella term for multiple eyesight issues astronauts can face.

“We want to further understand why SANS occurs, because right now, even though it’s one of the largest physiological barriers to spaceflight, we actually don’t know the (reason),” Ong told in an interview.


Published in the Nature Partner Journal of Microgravity on June 27, the study explains that an astronaut’s eyes will adjust in space, but after a long period of time, changes to their vision could be irreversible.

Due to a lack of gravity, fluids sometimes do not circulate as they should in space.

According to the NASA website, about one-third of astronauts will have their vision impacted on a trip as short as two weeks — on longer missions this number could double.

In some cases, eyesight will start to worsen while in space, making the tasks astronauts need to do more difficult.

“Historically, there were anecdotal reports of astronauts having vision changes while on the flight. This was even in the early shuttle missions,” Ong said. “It was difficult to read checklists on the cabin, things like that.”

Some common issues are optic nerve swells, eye flattening, which distort vision, cotton wool spots, which are dots that impair vision, and choroidal folds, which reduce vision.

“We have noticed there are some permanent changes in the eyes of some astronauts,” Waisberg told in an interview. “That would add more worries and when there are more people in space, the risks would just go up exponentially.”

Some of the issues could be corrected with glasses, and in other cases, the symptoms could go away on their own.

Research has allowed astronauts to take corrective measures by bringing specialized glasses to space with them to aid with blurriness.


Ong, Waisberg and their team are using different technologies to get a better understanding of how the eyesight of astronauts is impacted in space.

One such technology is a pair of VR goggles they came up with that conduct eye tests in a compact way.

“When you’re walking and looking at something, for example, you’re using your dynamic visual acuity, and they’ve done studies where, when astronauts come back to Earth after space missions, some of them perform poorly,” Waisberg said.

There are eye tests being conducted on space missions, but not ones that can easily test dynamic visual acuity, the researchers said.

“The tests we’re making the case for adding would be dynamic visual acuity, (and) sensitivity where we’d ask what degree of shades can you see, for example,” Waisberg said.

The goggles have passed early tests, but are not currently in use. Ong and Waisberg hope they will be launched in the next few years in space.

Like other products used in space, the researchers say the goggles could be used in remote communities where access to eye doctors and technology is limited.

“We’re hoping to increase accessibility to those exactly that have limited medical resources (to) prevent irreversible blinding pathologies,” Ong said.

The team is also optimizing AI technology to understand changes to humans’ eyesight in space in a more efficient manner.

“Subtle changes that you find more easily with the AI rather than someone manually checking, you can actually look more precisely into these changes,” Waisberg said. “And then using that we could help find correlations and also just discover things earlier.”

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