"Are
They Trifocals?"
"No, Trufocals"
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Jim Magay |
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So you may have seen the recent article in the NYT Science section about a new product called
Trufocals. It is a fluid filled Rx lens that adjusts power with a bridge-mounted slider that adjusts the near power from none to +275 and back again.
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The design consists of three parts; a back glass, a fluid-filled inner membrane that is essentially a piece of plastic-wrap-like material stretched across a ring whose surface curvature can be altered mechanically, and an outer prescription lens attached with magnets to the eyeglass frame. To change the focus, the user moves the slider on the bridge.
It is the brainchild of inventor Steven Kurtin - and Harry Potter would love them – they are perfectly round. (If you wish to have a liquid filled adjustable lens it must be round – no ifs, ands, or buts about it!) Steven is a long time inventor with a Cal-Tech degree in applied physics. Lest you think this is a dilettantish pursuit, Kurtin and his wife and many associates have invested millions in the research. The basic idea of a fluid lens whose focus can be changed mechanically goes back to a patent awarded in 1866, so obviously it is an insanely complex mechanical problem or we would have seen many iterations of the idea by now.
Another approach was tried by Luis W. Alvarez, (who in 1968 won the Nobel in physics), who posited a two-part lens that changed focus by sliding two lens components of opposing “saddle-back” shapes across each other.
Several international efforts are under way to adapt both fluid lenses and the Alvarez approach to the 1.3 billion people at the bottom of the economic pyramid that the WHO estimates as having no access to eyeglasses. Both the Center for Vision in the Developing World in Oxford, England, and U-Specs in Amsterdam (using the Alvarez principle) are working on glasses that can be distributed at a fraction of the price that glasses cost in the developed world.
Then there is Professor Joshua Silver who has invented a very basic silicone filled user adjustable lens and frame combination. The user injects more silicone fluid into the interstices in the lenses to sharpen their focus then breaks off, or locks the syringe, once the wearer is satisfied with the vision obtained (No – the syringes can’t be used for anything else).
On top of this our friends at PixelOptics are developing an electro active lens that was demonstrated last spring at Vision Expo and may come out next year. This would probably be a logical competitor to Kurtin’s glasses when it comes on the market.
But first to market honors must go to Trufocal at a whopping $895.00 retail. Multicolored temples are available and the bridge sizes vary with PD.
Beauty is in the eye of the beholder, a group of Trufocal wearers would not make the fashion gods quake, but they might incite a bit of jealousy among Harry Potter fans.
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