Progressive lenses are popular for other reasons than just “hiding the line.”  They work like a trifocal, in the sense that as you look straight ahead you have the distance correction, and as you look down the lens, power is progressively added so that there is a point of focus for both mid-range (arm’s length) and close detail work at the very bottom of the lens. 

Lined bifocals jump quickly from distance to near, once the pupil of the eye crosses the line.  The lined bifocal is usually easier to adapt to, and gives a larger field of view up close than the progressive.  In addition, there is a bit of distortion in the lower-periphery of no-line bifocals that is not experienced with the lined bifocal.  Most patients adapt well to the progressive by learning to keep their eyes in the same position and using a head turn to scan the environment.

The vast majority of patients will do well in one or the other, after a week or two of adaptation.  Only a very small percentage – perhaps 3% or less – simply cannot comfortably wear a bifocal of any type.