The 1.55mm-thick lenses incorporate a thin reflective telescope made of mirrors and filters; when light enters the eye it bounces off the series of mirrors and increases the perceived view of an object or person. It is hoped that the lens will improve the sight of people with age-related macular degeneration (AMD) -- the third leading cause of blindness globally.

AMD causes the loss of central vision due to gradual damage to the eye's retina and there are few options for cure or treatment. "AMD is the biggest problem where magnification is a proven visual aid," says Eric Tremblay, research scientist at EPFL in Switzerland.

Tremblay led the optical design of the lens, which is based on a surgically implantable telescope currently used by some patients with AMD, but which is more invasive than a lens. "With a contact lens, it's easy to try it," says Tremblay.

Making the switch

A key innovation with the lenses is the added ability to switch between magnified and regular vision through a complementary pair of glasses. The battery-powered glasses use LCD technology to watch the movement of the eye and a simple wink can alter their polarization and determine whether light entering is magnified or not. "Having the ability to switch on demand is attractive," says Tremblay.

The ability to selectively magnify your vision makes the design of the glass-lens combination more suitable for daily life. "When magnified you lose a lot of your field of view, your peripheral vision," says Tremblay. A strategic wink will enable users to keep an eye on their periphery, such as cars approaching them as they cross a street, whilst also being able to zoom in and recognize the faces of those around them.

The team developed their technology on scleral lenses, which have an increased thickness and diameter, making them commonly used for more special purpose eye care. "[They provide] a lot more area to work with," says Tremblay. The challenge these lenses bring with them, however, is comfort, as they impede the amount of oxygen reaching the eye.

The most recent prototype, unveiled by the team in February, overcame this challenge by introducing air channels to aid the flow of oxygen to the eye. But the team hopes to improve this further still by instead developing a contact lens solution saturated with oxygen which can be stored and slowly released into the eye. "[We will] build reservoirs into the back of the lens," says Tremblay.

The lenses have only been trialled on a handful of humans to test for comfort, with the majority of research to date performed in the lab using a model chemical eye. But more human trials are on the cards with the eventual goal of daily wearable contacts to aid the visually impaired.

"We want it to move in the direction of a real world vision aid," says Tremblay.

Getting smarter

These are not the first smart contact lenses. Other prototypes have been developed to monitor, as well as improve, health in both the eye and across the body.

Alcon, the eye care division of Novartis, formed a partnership with Google X in 2014 to develop smart-lens technologies for a range of medical eye care applications. One of the first examples of using lenses in this form was Sensimed , a spin-off also emerging from EPFL. Sensimed's Triggerfish technology monitors the progression of glaucoma -- the second leading cause of blindness, affecting more than 4.5 million people globally.

Glaucoma is a progressive cause of blindness caused by deterioration of the eye's optic nerve. The traditional test used by optometrists to monitor patients uses puffs of air to measure pressure in the eye but such measurements are not ideal.

"The big need in glaucoma is for a 24-hour picture of what's happening inside the eye," says David Bailey, CEO of Sensimed. Its smart lens uses strain gauges and sensors embedded inside a chip located in the lens to measure changes in the volume of liquid in the eye as a surrogate measurement of pressure. It can be worn over a 24-hour period to monitor pressure patterns and communicate data wirelessly to a recording device worn around the user's neck.

Optometrist James Wolffsohn, spokesperson for the British Contact Lens Association , looks forward to one day using technologies like the telescopic lens in clinical practice. "The lens seems an interesting concept to provide optical magnification to the retina when required," he says. But he adds that there will be challenges in reaching that stage: "It is currently a scleral lens and thick, including rigid mirror elements which are likely to affect corneal physiology and comfort." Wolffsohn has seen colleagues trial the more established Triggerfish technology to monitor glaucoma and is optimistic about the future of the field. "There are also many other exciting developments in innovative uses of contact lenses," he says.

"The eye is the window to many disease states," says Bailey, who believes contact lenses are the future for eye care, both in terms of clinical use and lifestyle management. More than 30 million people wear contact lenses in the United States alone, according to the Centers for Disease Control, which means they could be a non-invasive path to health management -- be it blindness progression or even insulin or alcohol level monitoring.

"Eye-sensing on contact lenses is here to stay ... in one form or another," says Bailey.