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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 ...
After many years as rivals, Essel and Silor merged on 1 January 1972 to form Essilor, then the world's third-largest ophthalmic optical firm. [1] Its first year of existence was marked by the creation of Valoptec, a non-trading company composed of stockholder managers who held half the company's capital stock, and the purchase of Benoist-Bethiot, a French lens manufacturer specializing in ...
It designs, produces and markets ophthalmic lenses, equipment and instruments, prescription glasses and sunglasses. It was founded on 1 October 2018 and its name is an amalgamation of the two major corporations which merged to create it; the French Essilor and the Italian Luxottica .
In the US market, soft contact lenses are approved by the US Food and Drug Administration. [2] The American Optometric Association published a contact lens comparison chart called Advantages and Disadvantages of Various Types of Contact Lenses on the differences between them. [3] These include: soft contact lenses; rigid gas-permeable (RGP ...
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.
Uncoated glasses lens (top) versus lens with anti-reflective coating. The reflection from the coated lens is tinted because the coating works better at some wavelengths than others. An antireflective , antiglare or anti-reflection ( AR ) coating is a type of optical coating applied to the surface of lenses , other optical elements, and ...
Using a phoropter to determine a prescription for eyeglasses. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.
Poly(allyl diglycol carbonate) (PADC) is a plastic commonly used in the manufacture of eyeglass lenses alongside the material PMMA (polymethyl methacrylate). The monomer is allyl diglycol carbonate (ADC). The term CR-39 technically refers to the ADC monomer, but is more commonly used to refer to the finished plastic.