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Space Agencies Are Trying to Keep Astronauts From Losing Their Sight
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The European Space Agency is racing to protect astronauts’ vision on future deep-space missions, commissioning British startup Siloton to develop a compact eye-scanning device that could prevent permanent sight damage. The agency has tasked the health-tech company with adapting its quantum-inspired imaging technology for space, ahead of the Artemis flights to the moon and other long-duration missions. Siloton’s solution shrinks the core components of the optical coherence tomography (OCT) machines used by optometrists onto a photonic chip smaller than a coin. This miniaturization is critical for spacecraft, where every kilogram and cubic centimeter carries a premium.
Spaceflight-associated neuro-ocular syndrome, or SANS, is a collection of eye and brain changes triggered by prolonged exposure to low gravity. According to NASA, about 70 percent of astronauts on the International Space Station experience some form of SANS, ranging from mild blurring to severe structural distortion. One of the most striking cases is NASA astronaut John Phillips, who arrived at the ISS in 2005 with 20/20 vision and returned to Earth six months later with 20/100 vision—a moderate visual impairment. While in orbit, bodily fluid shifted upward into his head, squashing his eyeballs, swelling his optic nerve, and pushing his retina forward.
Siloton, founded by physicists in 2020, is already working with the UK’s National Health Service to let patients with retinal conditions self-scan at home. “The ESA pretty much has the same requirements,” says cofounder and chief technology officer Euan Allen. “It's just in a totally different environment.” The company’s quantum technology uses entangled photons to dramatically reduce the power and size needed for OCT imaging, which measures the thickness of retinal layers.
Currently, astronauts on the ISS use a bulky, modified OCT device that requires real-time guidance from ground-based experts. As missions travel farther into deep space, communication delays will make that support impossible, so Siloton’s device automates the scanning process. This would allow astronauts to scan their retinas frequently without ground assistance, generating more data on ocular degeneration and potentially providing early warning signs before vision changes occur.
Medical engineers are particularly concerned about the operational risk of an astronaut losing their vision mid-mission, as well as the long-term health consequences. “The eye condition SANS is a serious health risk facing astronauts on long missions,” says Rebecca Evernden, director of the UK Space Agency. Developing a reliable, autonomous scanning tool is essential for managing ocular damage and eventually treating or preventing the condition altogether.
The engineering challenges go beyond miniaturization. Siloton must design the device to run without conventional batteries, which pose a significant fire risk in spacecraft, and solve the problem of stabilizing an astronaut’s head in microgravity—typically achieved with a chin rest on Earth. Allen, however, notes that his team has already tackled harder problems: “We're very confident, because we're trying to do that with 80-year-old patients who already have some level of visual imparity, whereas these will be highly trained astronauts who are much younger.”
Allen also believes the space research will directly benefit terrestrial medicine. “All this research and development work, in principle, is making our products that are going to go into the NHS much better,” he adds. The dual-use nature of the technology could bring advanced eye care to remote or underserved communities, while helping humanity reach the moon, Mars, and beyond.
As space agencies plan for longer and more distant missions, autonomous medical diagnostics are becoming a priority. SANS is just one of many physiological risks awaiting deep-space explorers, and innovations like Siloton’s chip could pave the way for a new generation of compact, self-operating health monitors. With NASA’s Artemis program aiming to land humans on the moon this decade and Mars missions on the horizon, the need for such technology has never been more urgent.
