title: Optical quality for keratoconic eyes with conventional RGP lens and simulated, customised contact lens corrections: a comparison.
abstract: OBJECTIVE
  To compare monochromatic aberrations of keratoconic eyes when uncorrected, corrected with spherically-powered RGP (rigid gas-permeable) contact lenses and corrected using simulations of customised soft contact lenses for different magnitudes of rotation (up to 15°) and translation (up to 1mm) from their ideal position.
  
  
  METHODS
  The ocular aberrations of examples of mild, moderate and severe keratoconic eyes were measured when uncorrected and when wearing their habitual RGP lenses. Residual aberrations and point-spread functions of each eye were simulated using an ideal, customised soft contact lens (designed to neutralise higher-order aberrations, HOA) were calculated as a function of the angle of rotation of the lens from its ideal orientation, and its horizontal and vertical translation.
  
  
  RESULTS
  In agreement with the results of other authors, the RGP lenses markedly reduced both lower-order aberrations and HOA for all three patients. When compared with the RGP lens corrections, the customised lens simulations only provided optical improvements if their movements were constrained within limits which appear to be difficult to achieve with current technologies.
  
  
  CONCLUSIONS
  At the present time, customised contact lens corrections appear likely to offer, at best, only minor optical improvements over RGP lenses for patients with keratoconus. If made in soft materials, however, these lenses may be preferred by patients in term of comfort.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, UK.
authors.forename: Amit
authors.initials: A
authors.lastname: Jinabhai
authors.forename: W
authors.initials: W
authors.lastname: Neil Charman
authors.forename: Clare
authors.initials: C
authors.lastname: O'Donnell
authors.forename: Hema
authors.initials: H
authors.lastname: Radhakrishnan
mesh_terms: D000328:Adult; D003261:Contact Lenses; D003263:Contact Lenses, Hydrophilic; D019781:Corneal Topography / Q000379:methods; D004867:Equipment Design; D006801:Humans; D007640:Keratoconus / Q000503:physiopathology / Q000628:therapy*; D012399:Rotation; D012720:Severity of Illness Index; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult