also referred to as "no-line bifocals"; multifocal lenses which provide visual correction for all distances. The different levels of correction are presented gradually over the lens. Typically, distance vision is corrected in the upper half of the lens, the middle area is for intermediate distances, and the lower part of the lens provides an increasing amounts of correction for close objects.
Lenses with bifocal or trifocal power with no visible line between the various focal lengths.
Lenses of multiple zones of optical power that provide both near and far focusing ability for presbyopic vision. For spectacle lenses, this is an alternative to bifocals or trifocals (elimination of tell-tale "lines" that separate lenses of differing powers). For contact lenses, these are sometimes referred to as "bifocal" contacts. But they are actually concentric rings (think "bullseye target) of varying powers that provide simultaneous near and far focusing ability. The brain ignores the fuzzy part of the image and concentrates on the high-resolution image.
Progressive lenses are state of the art boasting an infinite number of corrections. No-line bifocals have been round for over 20 years with major improvements taking place yearly. The progressive multifocals have a distance viewing area in the upper area of the lens, down to where the near correction begins. Major benefits of the lens is the lack of image jump on the segline.
(also, progressive addition lenses or PALs) Multifocal lenses whose corrective powers change progressively throughout the lens. A wearer looks through one portion of the lens for distance vision, another for intermediate vision, and a third portion for reading or close work. Each area is blended invisibly into the next, without the lines that traditional bifocals or trifocals have.
spectacle lenses that feature a continuous field of vision from up close to far away with no visible segment lines like traditional bifocal lenses.
Bifocal or trifocal lenses which appear to be single vision with no distinct lines between the various focal lengths.
Progressive lenses, also called progressive addition lenses, progressive power lenses, graduated lenses and varifocal lenses, are corrective lenses used in eyeglasses to correct presbyopia and other disorders of accommodation. A gradient of increasing lens power is added to the correction for the other refraction error, going from a minimum or nothing at the top of the lens to maximum magnification at the bottom of the lens. A wearer can then adjust the lens power required for clear vision at different viewing distances by tilting his or her head to place the line of sight through different parts of the lens.