title: Presbyopia compensation with a quartic axicon.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the performance of quartic axicons for presbyopia compensation. The working principle relies on profiting the high depth of focus of the axicons to supplement the reduced accommodation amplitude of presbyopes.
  
  
  METHODS
  We present the design equations of a particular kind of axicon to compensate a general presbyopia condition using simultaneous vision. A rotationally symmetric polynomial of fourth-order, corresponding to the well-known Seidel spherical aberration term, was chosen as its refractive profile. To validate its performance, we computed the retinal images with Stiles-Crawford apodization for a presbyopic eye compensated with this quartic axicon and compared them with those obtained without compensation or with other available solutions based on the simultaneous vision principle.
  
  
  RESULTS
  The quartic axicon provides an important improvement of the image quality for intermediate distance vision in comparison with conventional bifocal and trifocal solutions. The image quality, however, is still not optimum for all distances.
  
  
  CONCLUSIONS
  The results show the usefulness of the proposed approach and point out the need for developing further adapted optimizations.
authors.affiliation: Area de Optica, Departamento de Física Aplicada, Universidade de Santiago de Compostela, Galiza, Spain. fatxtutxa@usc.es
authors.forename: Jorge
authors.initials: J
authors.lastname: Ares
authors.forename: Ramón
authors.initials: R
authors.lastname: Flores
authors.forename: Salvador
authors.initials: S
authors.lastname: Bará
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Jaroszewicz
mesh_terms: D000065:Accommodation, Ocular / Q000502:physiology*; D004867:Equipment Design; D005139:Eyeglasses; D006801:Humans; D011305:Presbyopia / Q000503:physiopathology / Q000628:therapy*; D012029:Refraction, Ocular; D016896:Treatment Outcome