My experience after wearing the lineless/varifocal design for the past ten years? If they are ground correctly and the frame fits correctly, they're great. I've had poorly cut lenses in the wrong design frame that either doesn't fit well or gets loose easily.....and they suck.

While the above may be true for any pair of glasses, it is especially true of this type. The ones I now wear can't be beat. I think it was two pair ago that were horrendous.

Spaw