Eyeglasses with adaptive focus

The scientists first tested the imaging properties of the lens on a model human eye, then built prototype eyeglasses that real humans tested. The clinical results agreed with the model eye test.

Their tests showed that distance vision was no way impaired when the glasses were switched off and enabled close-up vision when switched on.

Prototype switchable focus glasses developed at the University of Arizona. Industry will commercialize a more attractive version. "We have demonstrated switchable liquid crystal diffractive lenses with high diffraction efficiency, high optical quality, rapid response time, and diffraction limited performance," they reported in the PNAS article. "These flat lenses are highly promising to replace conventional area division refractive, multi-focal spectacle lenses used by presbyopes," they wrote.

Estimates are that 93 percent of the world's population over age 45 have the condition called "presbyopia," where an aging person's eye lens loses flexibility and therefore, its ability to shift focus from distant to near objects.

Presbyopes will be some of the first to benefit from the UA research.

Computer screen display as Li switched the lenses on (left) for a clear view and off (right), without the power correction.

Electroactively focusing eyeglasses will revolutionize the $50 billion worldwide vision care industry, backers said at the outset of the UA research project.

Their major step in creating state-of-the-art liquid crystal diffractive lenses will have applications beyond vision care, the scientists predict. Tools with switchable lens elements would be valuable in dentistry, for example.

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