Progressive & Bifocal Lenses
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 in regular bifocals and trifocals.
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.