A quick google search for kryptok bifocals turned up the following information, as well as MANY other references. Apparently it's a very old version of a "blended edge" bifocal which, because of its rounded edges, is much less noticeable than the currently common options.
Picture: http://pic.wenzhouglasses.com/upload1/20071022/20071022951212231.jpg This is its history: http://www.eyecarebiz.com/article.aspx?article=50216 And this is a little information, describing it: http://kapleshwar.com/lenses/multifocal.asp "The Kryptok (or Fused) Bifocals have a circular arc for dividing line which is least visible compared to the other bifocals, this being its advantage. But these have the disadvantages of (a) Jump effect where there is a shift in the apparent position of object when the wearer looks from distance to near and (b) Chromatic aberration (color fringes) due to the use of different materials for main lens and segment. The Executive Bifocals are made of single piece of glass in which two different curvatures are ground. For this reason the dividing line is very prominent and the change in curvature can be felt at the dividing line by running the fingers across the lens surface. There can also be accumulation of dirt at the dividing line. There is minimal or no jump effect and this also offers a wider field of view for reading. These are averagely priced. The Univis ‘D’ Bifocals are also of the fused type but with a barely visible straight dividing line. They are also called Flat-Top bifocals. They have very minimal Jump effect, but are priced higher. The ‘D’ Bifocals are very popular aboard and are fast gaining popularity in India. All these are available either in Glass or Plastic (CR39). " On Mon, Feb 8, 2010 at 6:13 PM, GG <[email protected]> wrote: > Hi all, > I have been out of the forum for a while since I had already bought > enough glasses thanks to it (I have bought mora than 20 pairs on > line) and it was getting a bit of a hobby to buy glasses so I sort of > had to put a stop to it but.... the time has come that I need > bifocals. My eye doctor said that I could buy "kriptok invisible" bi > focals. He said that they do not look as bifocals. They do not have > the typical "bifocal line" Mind you, they are not "multifocals" but > bifocals that show no line. I searched the forum but could not find > any reference to such a thing. Does anybody know anything about this? > Than you all in advance.- > GG > > -- > Check us out at the oft-updated http://glassyeyes.blogspot.com! > > You received this message because you are subscribed to the Google Groups > "GlassyEyes" group. > To post to this group, send email to [email protected] > To unsubscribe from this group, send email to > [email protected] > For more options, visit this group at > http://groups.google.com/group/glassyeyes?hl=en -- Check us out at the oft-updated http://glassyeyes.blogspot.com! You received this message because you are subscribed to the Google Groups "GlassyEyes" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/glassyeyes?hl=en
