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Scientists Create Electronic Glasses That Can Automatically Focus On Whatever You're Looking At (engadget.com)
mmell writes: University of Utah scientists have created a prototype electronic lens which uses several technologies to customize the lens optics focusing on whatever the wearer is looking at. [Just like] the "oil lenses" in Frank Herbert's Dune series of novels, the electronic lens (a transparent LCD) can have its index of refractivity modified by application of a small electric current. While I can conceive many uses for this technology (in spacecraft instruments, webcams/Handycams, handheld binoculars and telescopes for example), these were developed as a replacement for the progressive lenses -- a.k.a. bifocals -- which are worn by many with less than perfect eyesight. Many eyeglass wearers don't tolerate bifocals well and I wonder if the adaptive optics in this prototype could relieve them of the need to carry multiple pairs of glasses? Whether they prove cost effective for the role of eyeglasses or not (and I can see no reason why they shouldn't), the applications for this technology seem quite diverse and potentially even revolutionary. I wonder how long it will be before these are more than just a prototype?
It's because 99.9% of progressive lenses have a semi-custom lens ground into one side, but a standardized lens ground into the other, with no regard for getting the optics right anywhere besides the center vertical axis.
It IS possible to make better glasses using raytracing (to design) and custom grinding (to implement) on both sides to "get it right" along the horizontal axis, too... but those lenses are expensive, and you'll only see a dramatic improvement if
1) the optician gets all the measurements precisely right (they rarely do, because full custom lenses are expensive, few stores sell more than one or two pairs a year, and they require more measurements than "normal" lenses that most techs don't fully understand);
2) The glasses are meticulously adjusted for proper alignment... and kept in proper alignment with frequent adjustments.
Realistically, you're looking at glasses that cost about $600-1,000/pair PLUS the frame cost.
The tech was developed for custom progressive lenses, but it can also be used to make better single-vision lenses for people with astigmatism. Normal glasses have a standardized sphere + base curve manufactured into one side, and a non-optimized cylindrical lens ground onto the other side (usually, without regard for lens angle or lens distance FROM pupil). I believe full-custom single-vision lenses run about $500-800 more than "regular" (non-optimized) ones.
The magic word to say & demand when asking about such lenses is "freeform" (often, used in conjunction with "custom" and/or "high-definition"). Just be aware that the optician's skill & experience fitting freeform lenses is ENORMOUSLY important. Even freeform custom lenses can suck if the optician is careless with his/her measurements. And demand the specific word "freeform" -- unlike other marketing terms, "freeform" has a very specific meaning in the industry. Not all lenses advertised as "hi-def" or "custom" are literally "freeform". At least one brand that's "semi-custom" exists that grinds a customized & optimized cyl onto one side of a lens manufactured with a standard sph+base curve on the other. For SV astigmatism, semi-custom might be good enough... but for progressive, you really want full-blown two-surface freeform custom lenses.