Varying slightly from a perfectly spherical shape: "Aspheric lenses are sometimes used for eyeglasses which are typically designed to give a thinner lens, and also distort the viewer's eyes less as seen by other people, producing better aesthetic appearances">

"Aspheric eyeglass lenses typically do not provide better vision than standard best form lenses, but rather allow a thinner, flatter lens to be made without reducing the optical performance."