title: Optical aspects of tolerances to uncorrected ocular astigmatism.
abstract: We approached the question of the visual tolerance to uncorrected astigmatism by exploring the changes in the retinal diffraction images brought about by astigmatism, as a function of spherical focus. Consideration of the Rayleigh and Maréchal wavefront criteria and of the changes in ocular modulation transfer function (MTF) broadly supports a value of 0.25 DC as a practical tolerance limit for uncorrected astigmatism. This study underlines the limitations of a geometrical optical approach to this problem in particular, and shows that the concept of the circle of least confusion may be misleading.
authors.affiliation: School of Optometry, University of Waterloo, Ontario, Canada.
authors.forename: W N
authors.initials: WN
authors.lastname: Charman
authors.forename: L
authors.initials: L
authors.lastname: Voisin
mesh_terms: D001251:Astigmatism / Q000503:physiopathology*; D006801:Humans; D008433:Mathematics; D055095:Optics and Photonics; D014796:Visual Perception / Q000502:physiology*