Staring at your mobile phone or laptop could speed up blindness, according to scientists.

A new study by Toledo University in Ohio found that blue light from digital devices triggers the production of a toxic chemical that kills light-sensitive cells in our eyes, according to the Daily Telegraph.

The resulting damage can speed up macular degeneration – a condition that affects the middle part of vision. Around one in seven people over 50 have some signs of the disease and there is no known cure.

Dr Ajith Karunarathne from the University of Toledo said: "We are being exposed to blue light continuously, and the eye's cornea and lens cannot block or reflect it."

Blue light has more energy and a shorter wavelength than other colours which is why it can cause more damage.

The research team said people should avoid using digital devices in the dark because this can dilate pupils and cause more blue light to enter the eyes.

"It's no secret that blue light harms our vision by damaging the eye's retina. Our experiments explain how this happens, and we hope this leads to therapies that slow macular degeneration, such as a new kind of eye drop," he added.

Macular degeneration begins with the death of photoreceptor cells - or light sensitive cells - in the retina. These cells need molecules called retinal to sense light and trigger a cascade of signaling to the brain. Shine blue light on retinal causes them to kill photoreceptor cells.

"You need a continuous supply of retinal molecules if you want to see," Karunarathne said. "Photoreceptors are useless without retinal, which is produced in the eye."

Dr Karunarathne's team is currently measuring light coming from television, mobile phone and tablet screens in the hope of better understanding how eyes respond to everyday blue light exposure.