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Grand Vision acquired Vision Express in 1997. The French parent company Grand Vision has clinics under various brands across Europe, and the rest of the world. Under franchise agreement there is a strong Vision Express brand present also in Latvian and Lithuanian markets.
A lens may be considered a thin lens if its thickness is much less than the radii of curvature of its surfaces (d ≪ | R 1 | and d ≪ | R 2 |).. In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces.
This list covers optical lens designs grouped by tasks or overall type. The field of optical lens designing has many variables including the function the lens or group of lenses have to perform, the limits of optical glass because of the index of refraction and dispersion properties, and design constraints including realistic lens element center and edge thicknesses, minimum and maximum air ...
A "slow" lens (one that is not capable of passing a lot of light through) might have a maximum aperture from 5.6 to 11, while a "fast" lens (one that can pass more light through) might have a maximum aperture from 1 to 4. Fast lenses are, by definition, larger than slow lenses (for comparable focal length), and typically cost more. [2]
Today the complex surfaces of a progressive lens can be cut and polished on computer-controlled machines, allowing 'freeform surfacing', as opposed to the earlier casting process, thus explaining the difference in price. In short, the price is based on the technology used and the year the lens came to market.
Optical Express is a provider of ophthalmology services including laser eye surgery, cataract surgery and lens replacement surgery in the United Kingdom and Europe. Optical Express is a trading name of DCM (Optical Holdings) Limited which operates as the Optical Express Group. [ 5 ]
Visionworks of America, Inc. (formerly known as Doctors' Value Vision) is an American company which operates or manages 711 optical retail stores in 40 U.S. states and the District of Columbia. [ 1 ] [ 2 ] [ 3 ] The company was incorporated in 1988.
This specifies the part of the prescription designed primarily to improve far vision. In a bifocal lens, this generally indicates what is to be placed in the top segment. NV is an abbreviation for near vision. This may represent a single-vision lens prescription to improve near work, or the reading portion of a bifocal lens.