In July 1969, Neil Armstrong became the first astronaut to walk on the moon. The Apollo 11 mission lasted about four days. Now more than 50 years later, astronauts are making much longer trips into space and looking ahead to the potential for even lengthier space flights that could keep astronauts in space for months and years at a time. That possibility brings a new physical challenge for astronauts to deal with: vision loss.
"When they go on long missions in space that are more than six months, almost 70% of astronauts have something called Spaceflight Associated Neuro-ocular Syndrome," said Tasneem Sharma, Ph.D., assistant professor of ophthalmology at Indiana University School of Medicine. "On Earth, gravity is pulling cerebral spinal fluid down from the brain and behind the eye. But in situations in space where there is no gravity, that doesn't happen. There is a fluid shift and a change in pressure of that fluid in the brain. As astronauts spend longer and longer in microgravity, then that fluid increases in the brain and can impact their eyes, changing the focus of the eye as a flattening from the back of the eye happens."
Sharma said when that change happens, astronauts' vision changes, too, causing them to need reading glasses or other interventions. Thanks to a grant in 2019 from NASA's Translational Research Institute for Space Health (TRISH) program, Sharma has developed a way to test different pressure changes on the back of the eye to study these effects.
"I have a human eye model and use donor eyes from human patients," Sharma said. "We put it in a system and mimic that increased pressure at different regions of the eye and see what happens."
Sharma first studied biomedical engineering at the University of Texas as an undergraduate student. While doing an internship on corneal tissue engineering, she began learning more about eye research and eventually decided to pursue a Ph.D. at the University of North Texas. She focused on glaucoma, a condition where the nerve connecting the eye to the brain becomes damaged, causing blindness.
"The eye is part of the brain and makes up the central nervous system," Sharma said. "We can do a lot of testing with eyes without needing to inject anything in the brain. It's a whole area that allows us the availability of tissue to do a lot of other unique experiments."
After earning her Ph.D., Sharma completed post-doctoral programs at the University of Iowa and the University of North Texas. Her work there involved studying donor eyes by cutting the eye in half and keeping the front of the eye alive to test glaucoma therapies. Then, Sharma had a new idea to keep the back of the eye for other studies.
"At that time, no one had really been able to take a human retina and keep it alive for long periods yet, because it's a high-energy requiring tissue," Sharma said. "We couldn't really test any therapeutics or do long-term research on it. We were basically discarding the back of the eye when we wanted to do a front of the eye experiment. So, I drew a bunch of diagrams and had a cousin who was a mechanical engineer at the time help make me a 3D design for a pressurized perfused system to keep that part of the eye alive for longer."
Creating the model was more difficult than Sharma expected. The back of the eye experiences different pressure than inside the eye, maintain two pressure chambers was challenging to recreate. After hundreds of attempted models over about a year and a half, Sharma finally found one that worked, called the Translaminar Autonomous System.
"I was like okay this is a model. I have it. Now what do I do with it?" Sharma said. "I put a description of my model on a NASA webpage I found, and about six months later, I got a phone call from TRISH."
TRISH is part of NASA's Human Research Program, focused on researching and developing new approaches to reduce risks of long-duration space exploration missions, including NASA's Journey to Mars. When TRISH discovered Sharma's human eye model, they asked her if it could be used to study Spaceflight Associated Neuro-ocular Syndrome. Sharma eventually received a grant from TRISH to study the syndrome in 2019. Soon after, she joined faculty at IU School of Medicine, and her team published their study results in npj Microgravity in October 2022.
"Here on Earth, when I'm sitting, I have a different pressure in my brain than when I'm standing or lying down and sleeping," Sharma said. "But in space, there's microgravity, which causes a constant pressure that does not change over time. That is what we tried to mimic with the model, and we found that there are degenerative changes in the eye with that mild, constant intracranial pressure over time. The nerve that connects the eye to the brain also changes shape, and we saw the more we changed the angle of that nerve, the higher the degeneration in the eye."
In astronauts, Sharma said NASA has found many of them experience some kind of choroidal folds, retinal folds and other clinical findings in the eyes, but for the most part, their symptoms are mild.
"If they are just in low Earth orbit, or on the international space station, these effects do not become significant until astronauts have a mission that is great than six months," Sharma said. "But then if we're talking about a long-term mission, more than 6 months, like the Artemis missions on the lunar surface, or the Mars missions, having significant changes in vision can be a mission critical situation."
Sharma is currently in the process of applying for a new grant through NASA to continue the research, hoping to next focus on testing other situations that could impact astronauts' eyes, like how different supplements or antioxidants could help. She could test other environmental conditions like high carbon dioxide and high salt content in the model. In the future, there is even the possibility of doing pre-clinical testing for astronauts in the future, like taking blood or cell samples pre and post flight to generate astronaut stem cells and retinal neurons to test specific therapies or supplements that could work specifically for their biology.
"Using stem cells, we've been able to create retinal neurons that we could eventually put in the human eye, then measure the function of the retina and other parts," Sharma said.
Her team is also collaborating with Loma Linda University for radiation studies and the lunar Zebro team from the Delft University of Technology in Netherlands to send donor eyes to the moon on a lunar rover to study changes in the eye on various parts of the moon.
"There are so many different areas to look at with these experiments," Sharma said. "NASA wants new and fresh ideas as they focus on long-term space exploration. It's an exciting field to be part of."
More information: Michael Peng et al, The ex vivo human translaminar autonomous system to study spaceflight associated neuro-ocular syndrome pathogenesis, npj Microgravity (2022). DOI: 10.1038/s41526-022-00232-5 , www.nature.com/articles/s41526-022-00232-5
Citation: Research targets vision loss in astronauts during long space missions (2023, April 5) retrieved 9 April 2023 from https://medicalxpress.com/news/2023-04-vision-loss-astronauts-space-missions.html
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FAQs
What are the vision problems that can be caused by prolonged space missions? ›
Nearly three-quarters of ISS astronauts experience changes in the structure or function of their eyes. “The changes associated with VIIP include globe flattening, hyperopic shift, choroidal folds, and optic disc edema,” stated the Optometry Times.
Do astronauts lose eyesight in space? ›The lack of gravity in space can have many different effects on the body, including on the visual system. Many astronauts have reported temporary and permanent changes in their vision upon returning from a trip to space.
What vision problem do many astronauts experience years after returning to Earth? ›One potential effect is Spaceflight-Associated Neuro-Ocular Syndrome (SANS), a condition in the eye that can lead to decreased sharpness of vision and swelling and flattening of structures in the eye.
What percentage of astronauts reported vision problems? ›Making it all the more perplexing, NASA says that signs of SANS appears in roughly 70 percent of Earth orbiting astronauts, but with significant individual variability. Overall, clarity over vision issues in space has come a long way since the February 1962 flight of Mercury astronaut John Glenn.
Do astronauts have vision problems? ›Even during a trip as short as two weeks, vision changes occur for about a 1/3rd of American astronauts. When the trip is longer – say, four to six months – that figure may double. But, before potential solutions can be proposed, scientists first have to understand what's causing these changes.
What are the three main challenges that astronauts encounter when they are in space? ›In space, the pull of gravity is very low. These systems can often remove too much fluid from our legs and put it into our chests and heads. Astronauts can then experience motion sickness, loss of balance, and loss of taste and smell.
How is eyesight affected in space? ›They found classic symptoms of what is now known as Space-Associated Neuro-Ocular Syndrome (SANS). Symptoms include swelling in the optic disc, which is where the optic nerve enters the retina, and flattening of the eye shape.
How can we prevent vision loss in space? ›A sleeping bag that mimics the pull of gravity could prevent astronauts' eyes from bulging in space, reducing the risk of vision problems on long journeys. About 70 per cent of people in space experience changes to the shape of their eyeballs, sometimes affecting their vision.
What do astronauts lose their sense of in space? ›From the early 1960s, astronauts found that their taste buds did not seem to be as effective when they were in space. Why does this happen in space? This is because fluids in the body get affected by the reduced gravity conditions (also called fluid shift).
What are some of the possible effects of long term space stays on an astronaut? ›If you stay for a long time in space, your muscles and bones will weaken, primarily in the legs and lower back. Gravity always acts on you while you're on the earth, so even if you're not really conscious of resisting gravity, you're always using the muscles of your lower body.
What are 2 of the problems astronauts have when coming back to Earth? ›
Finally upon returning home, crews will have to readapt to Earth's gravity. Transitioning from one gravity field to another is trickier than it sounds. It affects spatial orientation, head-eye and hand-eye coordination, balance, and locomotion, with some crew members experiencing space motion sickness.
What is the main problem that astronauts have to overcome in space? ›Star Wars would have you believe that the greatest challenges to space travel is asteroids, lack of resources like water or fuel, or even the threat of unfriendly, intelligent alien life. But in reality, scientists are finding that the biggest obstacle to today's space travel is dust. Yes, space dust.
What is the largest cause of vision loss worldwide? ›Cataract. Cataract is a clouding of the eye's lens and is the leading cause of blindness worldwide, and the leading cause of vision loss in the United States. Cataracts can occur at any age because of a variety of causes, and can be present at birth.
What is astronaut syndrome? ›Spaceflight associated Neuro-Ocular Syndrome (SANS)—formerly called visual impairment and intracranial pressure (VIIP) syndrome—is a constellation of findings and symptoms that have been found in astronauts who have undergone long duration space flight (LDSF) missions in microgravity environments (e.g., International ...
What is the failure rate of space missions? ›Many rockets have success records around 97 or 98 percent, Logsdon said. And the space shuttle, which NASA retired in July after 30 years of service, failed just twice in 135 missions, putting its reliability at about 98.5 percent (though those two failures tragically resulted in the deaths of 14 astronauts).
Do astronauts need perfect vision? ›Astronaut candidates must also be able to pass the NASA long-duration astronaut physical, which includes the following specific requirements: Distant and near visual acuity must be correctable to 20/20 in each eye. The use of glasses is acceptable.
What happens to an astronaut's eyes after a year in space? ›After a year, both astronauts had developed swelling of the optic nerve, a bundle of neurons that relays visual information from the retina to the brain. That swelling occurred at the disc-shaped head of the optic nerve, at the point just before the nerve leaves the eye (forming a blind spot on the retina).
Does space flight cause blurred vision? ›The sight condition, called spaceflight-associated neuro-ocular syndrome or SANS, was found to be associated with the volume of the fluid-filled spaces that surround blood vessels in the brain. The condition can cause astronauts to experience blurry vision and nausea.
What are four dangers faced by astronauts during space missions? ›- Radiation. The first hazard of a human mission to Mars is also the most difficult to visualize because, well, space radiation is invisible to the human eye. ...
- Isolation and confinement. ...
- Distance from Earth. ...
- Gravity (or lack thereof) ...
- Hostile/closed environments.
The environment of space is lethal without appropriate protection: the greatest threat in the vacuum of space derives from the lack of oxygen and pressure, although temperature and radiation also pose risks. The effects of space exposure can result in ebullism, hypoxia, hypocapnia, and decompression sickness.
What is the biggest challenge for astronauts living in space? ›
Astronauts on the ISS are exposed to more radiation from the Sun than people are on Earth as they are not fully shielded by Earth's magnetic field. Space explorers travelling further afield will be entirely outside this field and will therefore be exposed to significant radiation.
What problems do astronauts face in space? ›- Radiation. The first hazard of a human mission to Mars is also the most difficult to visualize because, well, space radiation is invisible to the human eye. ...
- Isolation and confinement. ...
- Distance from Earth. ...
- Gravity (or lack thereof) ...
- Hostile/closed environments.
The sky is so dark that an astronaut hiding from sunlight in a shadow would be able to see the stars. The answer to this question can be summed up in two words: no atmosphere. Planetary atmospheres cause bright light to scatter.
Can a person with weak eyesight be a astronaut? ›Yes, NASA astronauts can have myopia and still go to space. As a matter of fact, approximately 80% of astronauts wear glasses or contact lenses to correct some sort of vision problem. To be approved for space travel, astronauts must have 20/20 vision or better, with or without correction.
How do astronauts protect their eyes? ›The sunglass lenses worn by NASA astronauts are considerably darker than the commercial lenses, with a thin gold coating that offers total protection, not only against ultraviolet radiation, but also against the harmful infrared radiation in space.
How long does space blindness last? ›Former NASA Human Research Program Chief Scientist Mark Shelhamer noted in an interview with Air and Space that, for some, impairment has even lingered after returning from space and usually requires an astronaut being there for roughly six months.
Why can't we see into space during the day? ›Stars aren't visible during the sunlit hours of daytime because the light-scattering properties of our atmosphere spread sunlight across the sky. Seeing the dim light of a distant star in the blanket of photons from our Sun becomes as difficult as spotting a single snowflake in a blizzard.
What do astronauts miss the most? ›But one thing is certain: among the things astronauts miss the most when they're in space is home food. To successfully complete their missions, astronauts need to be emotionally and psychologically stable to withstand weightlessness, isolation and other challenges of long space flights.
What happens if an astronaut gets pregnant in space? ›"Anatomically and biologically," Baylor space medicine expert Jennifer Fogarty told the site, "there are no known impediments to human conception in space." But there are "serious concerns," she said, that the microgravity and radiation could mess up or even kill a fetus.
How much do astronauts get paid? ›The pay grades for civilian astronaut candidates are set by federal government pay scales and vary based on academic achievements and experience. According to NASA , civilian astronaut salaries range from $104,898 to $161,141 per year. Here are a few of the benefits offered to civilian astronauts: Health care.
What will happen if you stay in space for 10 years? ›
There is evidence that extended periods in space can result in dysregulation of the immune system. While there isn't too much risk of being exposed to pathogens, a compromised immune system can result in unwanted autoimmune responses and hypersensitivity.
How does prolonged space flight affect human brain structure and function? ›Long-duration spaceflights resulted in significant crowding of brain parenchyma at the vertex. Pre- to postflight structural changes of the left caudate correlated significantly with poor postural control; and the right primary motor area/midcingulate correlated significantly with a complex motor task completion time.
How long would you survive in space without a suit? ›90 seconds after exposure, you'll die from asphyxiation. It's also very cold in space. You'll eventually freeze solid. Depending on where you are in space, this will take 12-26 hours, but if you're close to a star, you'll be burnt to a crisp instead.
Why can't astronauts walk after returning from space? ›The human body is designed to work in Earth's gravity, which means that when astronauts return to Earth, their bodies have to readjust to the planet's gravitational force. Astronauts may experience a reduced sense of balance, mobility, and coordination after landing on earth.
Do astronauts faint when they come back from space? ›The lack of gravity astronauts encounter during spaceflight makes returning to the force of Earth's gravity a little disorienting. And when they return to Earth, they faint. A new study published Friday in Circulation, the American Heart Association's journal, has identified a way to avoid that.
What is the mental problem for astronauts? ›Post-mission personality changes and emotional problems have affected some returning space travelers. These have included anxiety, depression, excessive alcohol use, and marital readjustment difficulties that in some cases have necessitated the use of psychotherapy and psychoactive medications.
What are the five problems of space travel? ›a The key threats to human health and performance associated with spaceflight are radiation, altered gravity fields, hostile and closed environments, distance from Earth, and isolation and confinement. From these five hazards stem the health and performance risks studied by NASA's Human Research Program.
What was perhaps the greatest challenge of human space flight? ›The 2 major challenges associated with spaceflight are radiation effects and the physiologic consequences of a microgravity environment.
What is the true cause of vision loss? ›The leading causes of vision impairment and blindness are uncorrected refractive errors and cataracts. The majority of people with vision impairment and blindness are over the age of 50 years; however, vision loss can affect people of all ages.
Which country has worse eyesight? ›...
The 10 countries with the highest number of persons with vision loss, 2020.
| Country | China |
|---|---|
| Blindness | 8.9M |
| Moderate to severe | 51.9M |
| Mild | 57.7M |
| Near | 155.7M |
What effect does space have on your eyes? ›
70% of astronauts who spend time on the International Space Station (ISS) experience swelling at the back of their eyes, causing blurriness and impaired eyesight both in space and when they return to Earth. Sometimes, it's permanent.
Are astronauts eyes at risk after too much time in space? ›After decades of collecting data about how astronauts' vision is affected by spaceflight, scientists have identified a set of microgravity-induced changes to the human eye known as Spaceflight-Associated Neuro-Ocular Syndrome, or SANS. This condition is considered a risk to human health in long-duration spaceflight.
Why do astronauts don't age as much? ›During the Mars-500 experiment, six astronaut crews stayed in an isolated space and lived as if they were on Mars for 520 days. Cosmic radiation and microgravity were not replicated in the experiment, so the slower aging process found by scientists is caused by social isolation and other relative effects.
What mission is considered NASA's most successful failure? ›Imagine you are 200,000 miles away from home and you are about to run out of oxygen. What would you do? On April 11, 1970 Nasa launched John Swigert, Fred Haise, and Captain James (Jim) Lovell on Apollo 13 with the goal of landing on the moon.
What was the biggest space mission failure? ›On January 28, 1986, the Space Shuttle Challenger broke apart 73 seconds into its flight, killing all seven crew members aboard. The spacecraft disintegrated 46,000 feet (14 km) above the Atlantic Ocean, off the coast of Cape Canaveral, Florida, at 11:39 a.m. EST (16:39 UTC).
What famous space missions failed? ›STS-51-L: Space Shuttle Challenger Disaster
The disaster led to the deaths of all astronauts on board, including civilian Christa McAuliffe, a participant in NASA's Teacher in Space project who was to teach classes and perform experiments while in space.
Bones and muscles weaken
In space, where gravity is very weak, posture can be maintained without standing on your legs, and there's no need to use your legs to move about. Muscles weaken and bone mass decreases if you stay for a long time in space.
Without the proper diet and exercise routine, astronauts also lose muscle mass in microgravity faster than they would on Earth. Moreover, the fluids in the body shift upward to the head in microgravity, which may put pressure on the eyes and cause vision problems.
What is the eye sight problem for long distance? ›Long-sightedness is where you find it hard to see things nearby, but you can see things far away clearly. It's a common condition and wearing glasses or contact lenses can usually correct your vision. Long-sightedness is also known as hypermetropia or hyperopia.
How is vision affected in space? ›They found classic symptoms of what is now known as Space-Associated Neuro-Ocular Syndrome (SANS). Symptoms include swelling in the optic disc, which is where the optic nerve enters the retina, and flattening of the eye shape.
Are long trips to space linked to possible brain damage? ›
Researchers believe one possible cause of brain damage during space travel is weightlessness, as it disturbs the flow of blood from the head, which is thought to lead to an increase in pressure in the cerebrospinal fluid over time.
What are 5 physical consequences of space travel? ›Several consistent medical problems have been encountered by astronauts during space flights. These include vestibular dysfunction, weight loss, increase in height, upward fluid shift, anemia, cardiovascular deconditioning, muscle atrophy, and bone loss.
What effects does space have on the brain? ›An MRI study of cosmonauts showed that the brain's insula – which contains the vestibular area – was reduced in size and connections to other brain areas after 200 days in space. Other studies show that the ventricles of the brain become larger with space travel because of shifting fluid in the body.
What was the biggest problem is space travel? ›Problem: Space travel can present extreme environments that affect machine operations and survival. Like humans, machines are impacted by gravity, propulsive forces, radiation, gases, toxins, chemically caustic environments, static discharge, dust, extreme temperatures, frequent temperature variations and more.
What is one of the stressors during long duration space flight? ›Besides continuous exposure to microgravity and higher levels of ionizing radiation, astronauts experience increased levels of psychological stress. Social isolation, living in a confined environment, and a high workload can all contribute to elevated cortisol levels.
What causes blurred vision at near distance? ›Blurred vision can be caused by eye conditions, including: difficulty focusing your eyesight, such as with near-sightedness or far-sightedness. astigmatism (when the surface of the eye isn't curved properly) presbyopia (when your eyes find it harder to focus as you age)
How do you fix blurry vision long distance? ›- Rest and recovery. Human eyes are sensitive and need rest just like the rest of your body, so make sure you're getting enough decent sleep. ...
- Lubricate the eyes. ...
- Improve air quality. ...
- Stop smoking. ...
- Avoid allergens. ...
- Take omega-3 fatty acids. ...
- Protect your eyes. ...
- Take vitamin A.
Your eyesight could be getting worse because you have an uncorrected refractive error. If you begin to struggle to see far away or close up, then you should visit your optician for an eye examination. Your optician is able to diagnose a multitude of vision problems and offer advice on how to manage them.