I've never seen this bifocal...

[chip anderson]

It's a panofocal. I once watched these being made. facinating. Took three pieces of glass fused together, Five surfaces to polish and three to be fused together.
Was a most excellent byfocal by B&L. Haven't seen one since about "63 though.

Chip

[CME4SPECS]

Center of bifocal is about 2mm higher than edges of bifocal. Curved up I guess.

Sorry, we don't pay attention to details very well. They are Bristolite or Cosmolit. And they are aspheric.

[Judy Canty]

FYI:

http://www.eyecarebiz.com/article.aspx?article=50216

[sharonseyes]

That sounds like an old smart seg. One of the earlier progressives. I've seen a few. The top, above the curved line is the distance, the top of the bifocal is intermediate and the bottom of the bifocal is for near point. I'm not sure they are made any more.

[CME4SPECS]

That sounds like an old smart seg. One of the earlier progressives. I've seen a few. The top, above the curved line is the distance, the top of the bifocal is intermediate and the bottom of the bifocal is for near point. I'm not sure they are made any more.

Smart seg had a straight top. With a deeper seg than usual.

[harry a saake]

if its glass and curved at the top and around the two top edges then it is as a B@L panoptik, if it is curved at the top and not rounded on the edges, its just an old curve top

B@L,s panoptik was one of the finest line bifocals ever made, but it was so radical in its look it was a hard sell

[JerryR]

Lens style started out many years agop as a B&L Panoptik, which not only had a curved top but also rounded corners,later styles had pointed corners like a FT, with the curved top called a ful-vue and still available as a curve top

[hcjilson]

Lens style started out many years agop as a B&L Panoptik, which not only had a curved top but also rounded corners,later styles had pointed corners like a FT, with the curved top called a ful-vue and still available as a curve top

It was an AO design called Full Vue C or as we used to write-FVC-20-or 22 (at that time it was available in 2 sizes.....28 hadn't been brought out yet!)

Smart Seg did indeed have a flat top and it was a progressive seg, not progressive lens.

[Chris Ryser]

If the top curves slightly down it's a panafocal (or panofocal) by B&L. Completly eliminated jump on going into seg. Dropped because it was too expensive to make.
Chip

The original was called Panoptic made by Bausch and Lomb. was a fused curve top in glass and was the Cadillac in bifocals in the 1950's and 60's.

[MarcE]

I don't know much history, but if you want something stronger and thinner than CR-39, try Indo's curve top. It's 1.52 index, clearer than regular plastic, stronger and lighter. It's a premium "plastic".
BTW, I have only used Indo's SV lenses, not the curve top or progressives.

or call the lab, they may be able to get something like that from Sola or Rodenstock.

[harry a saake]

the indo is a great lens, and very white in its color, i wrote an article about that lens in VCPN back about two years ago, which you can probably access on VCPNS on line

[akeroptical]

I agree probably a Rodenstock Curve top. I am away from my lens book but I believe you can still get curve tops. You need the lens book from FRAMEDATA, I refer to it often.

[Eyeful]

Vision Ease will sell the blanks.

They do here in the UK at least.

Its a C28 and will cost about double the price of a flat top.

[Scott R]

Sounds like a curve top. Most larger labs like Italee ect... should be able to get them for you. Even if its not in their regular stock they can usually order them for you and have them in a couple of days.

[Chris Ryser]

Center of bifocal is about 2mm higher than edges of bifocal. Curved up I guess.

Lensdale
Let’s return now to Lensdale, where I spent 40 years as an engineer, to give you a brief picture of the company.
In the late 1800’s, Lensdale made double convex and concave items and flat cylinders. Then it made periscopic lenses (first step towards deeper curves inside for better vision). By 1910, it was making the center series - spheres and toric lenses with much deeper inside curves. The following documents Lensdale’s further activity:
1910 The Kryptok bifocal, the first fused bifocal.
1915 The one-piece bifocal.
1925 The Tillyer “D” bifocal, a fused bifocal, color corrected.
About 1925 Tillyer Series, spheres and toric lenses corrected for marginal vision.
1935 The Tillyer, a curved top bifocal.
1940 The Tillyer Flat Top.
1960 The Trifocal Executive, a one-piece with a wide field.


See more at : http://www.dickwhitney.net/AOMcMaster.htm

This suggest's that the curve top lens existed before the flat top bifocal.

[Bezza]

Kind of off topic but just out of interest i wonder how many of you have come across the B-segment bifocal, its like a standard flat top but without the curved bottom part.
I have only ever seen one of these once and it was during my SMC(tech) exam. I have a funny feeling that Norville still make them but they have never been very popular despite the apparent optical benefits.

[harry a saake]

what you are talking about is an old ribbon seg as we use to call them, it was suppose to be ideal for golfers

[shanbaum]

what you are talking about is an old ribbon seg as we use to call them, it was suppose to be ideal for golfers

Harry, I recall two segs - the ribbon, or "R" seg, and the "B" seg. The latter was a bit taller than the former. I'd guess the R was around 9mm and the B, 14.

I wonder who came up with these letter designations?