Progressive lenses are no-line multifocal eyeglass lenses that look exactly the same as single vision lenses. In other words, progressive lenses will help you see clearly at all distances without those annoying (and age-defining) “bifocal lines” that are visible bifocals and trifocals.
The power of progressive lenses changes gradually from point to point on the lens surface, providing the correct lens power for seeing objects clearly at virtually any distance.
Bifocals, on the other hand, have only two lens powers — one for seeing distant objects clearly and a second power in the lower half of the lens for seeing clearly at a specified reading distance. The junction between these distinctly different power zones is defined by a visible “bifocal line” that cuts across the center of the lens.
Progressive lenses sometimes are called “no-line bifocals” because they don’t have this visible bifocal line. They have a significantly more advanced multifocal design than bifocals or trifocals.
This picture shows the vision obtained with Progressive Lenses where all objects at every distance are visually clear.