title: Tscherning ellipses and ray tracing in ophthalmic lenses.
abstract: In this paper the exact shape of the solutions to the equations for lenses free of oblique astigmatism, as well as those free from curvature of field or peripheral focus error, are presented. These solutions, as expected, resemble the Tscherning ellipses, but strongly deformed.
mesh_terms: D004867:Equipment Design; D005139:Eyeglasses; D006801:Humans