Swimming goggles could be used to protect astronauts’ eyes on long missions to Mars, a new study suggests.

Experiments by Nasa scientists found goggles protected vision by boosting the pressure of fluid inside the eye.

Astronauts on long missions at the International Space Station have been found to experience changes to their eyes that last for years.

Known medically as intraocular pressure (IOP), the phenomenon can prompt a host of symptoms, including "cotton wool spots" - fluffy white spots on the retina - and swelling of the optic nerve.

Up to 75 per cent of astronauts develop neuro-ocular changes, including decreased visual sharpness.

The effects of microgravity on the circulatory system have been blamed, including shifts in body fluid and increased pressure on the brain.

The new findings were based on 20 men at NASA's Johnson Space Centre in Houston - with ten wearing swimming goggles and the others going eyewear free.

On three separate days they completed exercises while on their back and tilted back head-first - to simulate the effect of physical activity in space.

Dr Jessica Scott, of the Universities Space Research Association, Houston, said: "Swimming goggles firmly compress the skin around the eye."

"These findings suggest modestly increasing intraocular pressure with swimming goggles could be used to mitigate spaceflight-associated neuro-ocular syndrome.