title: Power maps and wavefront for progressive addition lenses in eyeglass frames.
abstract: OBJECTIVE
  To evaluate a method for measuring the cylinder, sphere, and wavefront of progressive addition lenses (PALs) in eyeglass frames.
  
  
  METHODS
  We examine the contour maps of cylinder, sphere, and wavefront of a PAL assembled in an eyeglass frame using an optical system based on a Hartmann test. To reduce the data noise, particularly in the border of the eyeglass frame, we implement a method based on the Fourier analysis to extrapolate spots outside the eyeglass frame. The spots are extrapolated up to a circular pupil that circumscribes the eyeglass frame and compared with data obtained from a circular uncut PAL.
  
  
  RESULTS
  By using the Fourier analysis to extrapolate spots outside the eyeglass frame, we can remove the edge artifacts of the PAL within its frame and implement the modal method to fit wavefront data with Zernike polynomials within a circular aperture that circumscribes the frame. The extrapolated modal maps from framed PALs accurately reflect maps obtained from uncut PALs and provide smoothed maps for the cylinder and sphere inside the eyeglass frame.
  
  
  CONCLUSIONS
  The proposed method for extrapolating spots outside the eyeglass frame removes edge artifacts of the contour maps (wavefront, cylinder, and sphere), which may be useful to facilitate measurements such as the length and width of the progressive corridor for a PAL in its frame. The method can be applied to any shape of eyeglass frame.
authors.affiliation: *PhD †BSc Grupo de Óptica Aplicada, Departamento de Física, Universidad Nacional de Colombia, Ciudad Universitaria, Bogotá D.C., Colombia (all authors).
authors.forename: Yobani
authors.initials: Y
authors.lastname: Mejía
authors.forename: David A
authors.initials: DA
authors.lastname: Mora
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Díaz
mesh_terms: D000465:Algorithms; D005139:Eyeglasses; D005583:Fourier Analysis; D006801:Humans; D008962:Models, Theoretical; D055095:Optics and Photonics; D012029:Refraction, Ocular / Q000502:physiology