NASA tests pocket device to prevent astronaut blindness

Astronauts on long missions may soon carry a pocket-sized device originally made for elderly patients to check their own eyes, after NASA and the European Space Agency began testing it aboard the International Space Station.

The tool, called the ForeseeHome AMD Monitor, was designed to spot early signs of age-related macular degeneration in people over 80. But space agencies now see it as a fast, low-power way to watch for a far more urgent problem: spaceflight-associated neuro-ocular syndrome, or SANS. Doctors first noticed the condition among astronauts after months in microgravity, when pressure shifts inside the skull seem to flatten the eyeballs and blur vision.

Up to two-thirds of astronauts on long flights report vision changes, with some suffering permanent damage. The syndrome shows up as swollen optic discs, folds in the retina, and in serious cases, a bulging eyeball that never fully recovers on Earth. Researchers suspect fluid shifts in zero-G push pressure backward into the head, flattening the eyeball like a grape becoming a raisin. The ForeseeHome device, which flashes a grid of dots on a small screen, can detect the earliest distortions in central vision. Astronauts only need a few minutes each week to run the test.

Space agencies plan to send the device on the next cargo run to the station and, if it passes, include it in the medical kits for the planned Artemis moon landings and eventual Mars trips. The goal is to flag problems early enough to adjust diet, exercise, or even pressure in the spacecraft. With astronauts expected to spend years away on lunar bases or en-route to Mars, keeping eyes sharp is no longer optional—it’s mission-critical.