Vuarnet sunglasses

[Paul Smith LDO]

Late to the party with my reply, but really how many patients have been wearing glass all their lives? The percentage of glass lens wearers must be low and one would think even that percentage must be getting lower and lower every year.

For some, I have sold more glass lenses this year than I have over the last 5 years. As a recent new home owner I have conversely scratched more of my high index lenses than ever before, hence my new work around the home lenses are glass. More options more solutions.

[Dr. Bill Stacy]

Digital surfacing of glass uses the same brass diamond impregnated discs that regular processing of glass uses. There is no "jack hammer effect". The disc is about 37 mm in diameter, full impregnation, spins at about 25,000 rpm. Glass does not use a single-point or multi-flute cutter like a plastic lens would use. To do glass, digital generating has been around since about the year 2000 in the ophthalmic industry. In fact, depending on the lens generator, a fining step may not even be needed, depending on how slow the machine is set to cut the last few tenths of a mm off the lens surface. All that's been done is to modify the the generator program to run glass instead of plastic.

And surfacing is not done with a "flexible sponge", it is done with a rubber bladder, upon which has been mounted typical glass polishing pads.

Yes, the process will take longer than conventional glass fining, but the result is as good, if not better optics than the same lens done in plastic.

Lenticular ends is one of two things: either a prismatic myodisc at the temporal edge of the lens, or a continuous (step) back cut all the way around the lens edge that has been polished (or sometimes not). The design of the lenticular would depend on the frame style and the prescription power of the lens.

If I understand your post, you're describing a method of generating and polishing glass lenses like those on cameras. I don't think that method will exactly do freeform surfacing such as the front surface of a Progressive lens. Maybe I'm wrong, but I can envision it doing a front surface aspheric without cyl, maybe even a back side atoric without cyl, but in my ignorance, cannot conceive of how the freestyle optics of a PAL can be done on glass without doing some molding with metal molds and casting the glass front surface. But it's fun to speculate.

Think outside the box and always challenge authority

[MikeAurelius]

Freeform is routinely done on either side. On glass. Every day.

[Paul Smith LDO]

If I understand your post, you're describing a method of generating and polishing glass lenses like those on cameras. I don't think that method will exactly do freeform surfacing such as the front surface of a Progressive lens. Maybe I'm wrong, but I can envision it doing a front surface aspheric without cyl, maybe even a back side atoric without cyl, but in my ignorance, cannot conceive of how the freestyle optics of a PAL can be done on glass without doing some molding with metal molds and casting the glass front surface. But it's fun to speculate.

Think outside the box and always challenge authority

How about contacting FEA; eliminating the speculation and gaining the knowledge.

[Dr. Bill Stacy]

Ok I did contact them and the gal I talked to didn't know much about it. However, they have some slick videos on their web site that do a fine job of presenting plastic free form lens surfacing and polishing. Didn't find anything about glass on the site. They even have their wholesale price list on line. Yep, no glass mentioned. Finally, their Opto Tech seemed to be only generating and polishing the inside surfaces. Now I feel a little smarter.

[Paul Smith LDO]

FEA offers the, Shamir In Touch; a full back surface progressive design in glass.

[Dr. Bill Stacy]

The lady on the phone said it was just the Eaglet that was in glass. At any rate, I'm not sure what full back surface means. I'm guessing that means the front surface is spherical? Aspheric? Atoric? But not any free form progressive stuff on the front?

I'm guessing they don't do much glass there. The gal did say they are planning on expanding into a new facility for the glass.