Telescopic contact lenses developed in Switzerland allow users to zoom in on distant objects, as if they were looking through binoculars. The lenses can magnify a wearer's vision up to 2.8 times.

The new contact lens can be switched between normal and magnified states, as images are carried along a pair of independent pathways. A pair of glasses worn with the lenses recognizes winks, while ignoring quick involuntary blinks, in order to change modes. Users wink their right eye to view the world in magnified mode, and a left eye blink is used to return to normal vision.

Around 285 million people worldwide suffer from some form of visual impairment. The leading cause of blindness is age-related macular degeneration (AMD).

"It's very important and hard to strike a balance between function and the social costs of wearing any kind of bulky visual device. There is a strong need for something more integrated, and a contact lens is an attractive direction. At this point this is still research, but we are hopeful it will eventually become a real option for people with AMD,"  Eric Tremblay at the École polytechnique fédérale de Lausanne in Switzerland said.

This is the latest version of the contact lens system, first developed in 2013, as part of research funded by the Defense Advanced Research Projects Agency. Since the initial version, researchers have been working on updating the lens, making them easier to wear for longer periods of time. The latest version is larger than traditional contacts and rigid. Oxygen needs to pass through the lens and onto the eye. This is accomplished through tiny pores built into the contacts.

Reflective surfaces in the lens function like a telescope along one path of light, while a small aperture allows for light to pass along a different route, little altered by the system.

"There are glasses already on the market for people with AMD that have mounted telescopes, but they tend to look bulky and interfere with social interaction. They also do not track eye movement, so you have to position your eyes and tilt your head to use them," the researchers stated.

Further research is aimed at delivering images of higher quality, as well as a less intrusive lens. Other optical devices could also benefit from the technology, say researchers.