Engineers at the University of Utah have created eyeglasses with lenses that can be adjusted and focused by the wearer. The lenses have flexible membranes that house liquid glycerin. A battery-powered mechanism moves the membranes, changing the shape of the lens and its focal point.
The designers included an infrared distance sensor to make the glasses responsive. This senses its distance from objects and then automatically focuses the lenses.
For now, the glasses are slightly bulky and would not be suitable for mass market. However, engineers are hoping to reduce size so the design may one day compete with bifocals.
Here is an excerpt from the study, published in the journal Optics Express:
"The full field of view can be restored if the eyeglass lenses have a variable power that adaptively accommodates to the object distance. In order to address the need of most eyeglass corrected problems, the lens should have an accommodation range from −4 to + 4 diopters. Furthermore, the lenses should be light and thin with the aperture of 30-45 mm in diameter. The lens power should be adjusted at a minimum electrical power expense to ensure long battery operation. In this paper we present the implementation of an electrically actuated variable power lens with aperture and power range suitable for adaptive eyeglass applications."