Editing Corrective lens (section)

===Spheric vs. aspheric, atoric, etc.===
Lens manufacturers claim that [[aspheric lens]]es improve vision over traditional spheric lenses. This statement could be misleading to individuals who do not know that the lenses are being implicitly compared to "a spheric flattened away from best-form for cosmetic reasons".{{citation needed|date=January 2008}} This qualification is necessary since best-form spherics are always better than aspherics for an ophthalmic lens application.<ref name="Meister_lensdesign"/> Aspherics are only{{citation needed|date=January 2008}} used for corrective lenses when, in order to achieve a flatter lens for cosmetic reasons, the lens design deviates from the best-form sphere; this results in degradation of the visual correction, degradation which can, in some part, be compensated for by an aspheric design. The same is true for atoric and bi-aspheric.

While it is true that aspheric lenses are used in cameras and binoculars, it would be wrong to assume that this means aspherics/atorics result in better optics for eyewear. Cameras and telescopes use multiple lens elements and have different design criteria. Spectacles are made of only one ophthalmic lens, and the best-form spheric lens has been shown to give the best vision.{{Citation needed|date=April 2008}} In cases where best-form is not used, such as cosmetic flattening, thinning or wrap-around sunglasses, an aspheric design can reduce the amount of induced optical distortions.{{Citation needed|date=January 2008}}

It is worth noting that aspheric lenses are a broad category. A lens is made of two curved surfaces, and an aspheric lens is a lens where one or both of those surfaces is not spherical. Further research and development is being conducted{{Citation needed|date=January 2008}} to determine whether the mathematical and theoretical benefits of aspheric lenses can be implemented in practice in a way that results in better vision correction.