Wink once to zoom. Telescopic contact lenses that let the wearer switch between normal and magnified vision are coming into focus. The latest prototype – unveiled today at the AAAS Annual Meeting in San Jose, California – could one day help people with visual impairment. The lenses might be particularly useful for people with macular degeneration, a debilitating condition in which people gradually lose their central vision.
It is the leading cause of visual impairment in the UK and affects millions worldwide. Developed by a team led by Eric Tremblay at the Swiss Federal Institute of Technology in Lausanne, the rigid contact lens covers the sclera, or whites of the eyes, making it larger than an ordinary lens. Within it are tiny aluminium mirrors, arranged in a ring around the centre. When light streams through, the mirrors bounce it around several times, causing objects to appear 2.8 times larger than they really are.
To toggle between the magnified and normal views, the lenses must be worn with a pair of electronic glasses. A wink with one eye makes the glasses switch to a polarised filter that directs light to the telescopic part of the lenses. Winking with the other eye switches the setting back to let light pass through normally.
The prototype builds on a previous version
that did not let the user toggle the zoom. The design of the lenses has also been altered, to allow oxygen to reach the eye. Since the lenses are large and thick in the middle, they limit airflow to the surface of the eye and can only be worn for a limited amount of time. To fix this, the team added small channels to let air travel around the underside of the lens.
With better airflow, the researchers hope to begin human trials. So far the researchers have tested the tech with a life-size mechanical model of the eye that relays what it sees to a computer screen.
Smart contact lenses could also let users keep tabs on medical problems. At the University of California at Davis, researchers have built lenses with minute pressure sensors to check for glaucoma. Another set, developed at the University of Washington in Seattle, can check glucose levels, which would be useful for people with diabetes.
People with macular degeneration lose their eyesight gradually, with damage to the retina making their vision increasingly blurry. Existing treatment options are limited to surgery, or wearing visual aids that resemble opera glasses – known as bioptic telescopes.
The zoom lenses might be tricky for people who are visually impaired or who have some form of infirmity to pop on and off with ease, says James Handa, an ophthalmologist at Johns Hopkins School of Medicine in Baltimore. But he thinks they could be a popular option for many.
“If it affords them the ability to get enough magnification for their loss of vision, absolutely,” he says. “It’s a highly innovative and very creative idea.”
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