multi-focal glasses

"The electronic glasses, which have been developed by US firm PixelOptics, can be adjusted manually to view objects at different distances by pressing a button on the side of the frames.  Unlike traditional bifocals, which only allow the wearer to focus "near" or "far", the electronic lenses have a range of in-between settings. "  http://www.telegraph.co.uk/technology/news/7840034/Bye-bye-bifocals-hello-electronic-spectacles.html