Ads
related to: progressive lens power gradient
Search results
Results From The WOW.Com Content Network
The gradient starts at the wearer's distance prescription at the top of the lens and reaches a maximum addition power, or the full reading addition, at the bottom of the lens. The length of the progressive power gradient on the lens surface depends on the design of the lens, with a final addition power between 0.75 and 3.50 dioptres.
However this was unlike modern progressive lenses. It consisted of a conical back surface and a cylindrical front with opposing axes in order to create a power progression. This design was never commercialized. However, due to this patent, Essilor cannot technically be considered the creator of the first progressive lens.
Current bifocals and progressive lenses are static, in that the user has to change their eye position to look through the portion of the lens with the focal power corresponding to the distance of the object. This usually means looking through the top of the lens for distant objects and down through the bottom of the lens for near objects.
For people with presbyopia and hyperopia, bifocal and trifocal glasses provide two or three different refractive indices, respectively, and progressive lenses have a continuous gradient. [1] Lenses can also be manufactured with high refractive indices, which allow them to be more lightweight and thinner than their counterparts with "low ...
Those who wear eyeglasses with so-called "progressive" lenses, in which the focal length gradually changes so as to ease the viewing of close objects using the lower part of the lens, may find that viewing a stereogram is easier if the glasses are pushed up a little so that the stereogram is viewed through a part of the lens optimized for ...
Multifocal lens may refer to: Progressive lens, used in eyeglasses; Multifocal intraocular lens; Multifocal diffractive lens, a diffractive optical element used with ...