in every way
Progressive lenses can be called progressive addition lenses (PAL), progressive power lenses (PPL) or graduated prescription lenses.
How do they work? A channel (or corridor) of different lens powers runs down the front of a progressive lens. This seamless channel allows the wearer to look up to see objects at a distance, look straight ahead to see objects at middle distance, and down to read or do other close-up activities without changing glasses.
What are the benefits? Progressive lenses are often preferred aesthetically as they don’t have the visible line that marks the two different zones of a bifocal lens (or lines, in the case of a trifocal lens). Instead, progressive lenses provide a seamless graduation of lens strength. This avoids the jump in vision a wearer gets with bifocals and trifocals, and actually trains the eye to improve vision.