Although most bifocals and trifocals have visible lines at the border of lens segments, there is a blended round-seg bifocal that has a less noticeable near segment than its regular round-seg cousin.The near seg is blended into the distance portion of the lens so that it is virtually invisible.
Blended bifocal lens.
With no visible lines, a blended round seg bifocal offers a more youthful appearance than lined bifocals and trifocals.But a drawback of the blended bifocal is that the optics of the lens are slightly distorted at the blended border between distance and near zones.This may be bothersome to some wearers.
Blended bifocals should not be confused with progressive lenses, which are special no-line multifocals that incorporate all corrections, from distance to close-up, into one lens without any separation of the various visual zones by lines.
Today, progressive lenses are significantly more popular than bifocals or trifocals, partly because they provide a younger appearance with no age-revealing seg lines.