These lenses are meant for a single focal point. They can be used to see distance, computer distance or reading distance.
Lined bifocals and trifocals are called multi-focal lenses that have a physical line called a "segment." Bifocals have two focal lengths, typically distance and reading, although they can be configured differently based on wearer needs. Trifocals contain three focal points: distance, intermediate (or computer), and near (or reading).
Progressive lenses go by many names, no-lines, no-line bifocals, no-line trifocals, PALs, and progressives. No matter what you call them they are all the same thing, multi-focal lenses that have no visible line in them. These lenses are not only more aesthetically pleasing, but they are also available in a wider variety of lens styles and materials.
Computer lenses are a specialty type of lens that provides users with maximum intermediate distance while also providing a limited amount of distance and typical amount of reading distance. These lenses are great for the office environment when working on the computer is a large part of the wearer’s day.
