title: Visual performance and optical quality with soft lenses in keratoconus patients.
abstract: OBJECTIVE
  To assess visual performance and ocular aberrations in keratoconic patients using toric soft contact lenses (SCL), rigid-gas-permeable (RGP) contact lenses and spectacle lens correction.
  
  
  METHODS
  Twenty-two keratoconus patients (16 RGP lens wearers and six spectacle wearers) were fitted with toric SCL. Ocular aberrations were measured with and without the patient's habitual RGP lenses and with the SCL in place. In the spectacle wearers, aberrations were measured with and without the SCL. Visual performance (high- and low-contrast visual acuity) was evaluated with the patient's habitual correction and with the SCL.
  
  
  RESULTS
  In the RGP lens wearers both the habitual lenses and the toric SCL significantly reduced coma, trefoil, 3rd-order, 4th-order cylinder and higher-order root-mean-square (RMS) aberrations (p ≤ 0.015). In the spectacle wearers the toric SCL significantly reduced coma, 3rd-order and higher-order RMS aberrations (p ≤ 0.01). The patients' habitual RGP lenses gave better low-contrast acuity (p ≤ 0.006) compared to the toric SCL; however, no significant difference was found between lens types for high-contrast acuity (p = 0.10). In the spectacle wearers no significant differences in visual performance measurements were found between the patients' spectacles and the toric SCL (p ≥ 0.06).
  
  
  CONCLUSIONS
  The results show that RGP lenses provided superior visual performances and greater reduction of 3rd-order aberrations compared to toric SCL in this group of keratoconic patients. In the spectacle-wearing group, visual performance with the toric SCL was found to be comparable to that measured with spectacles. Nevertheless, with the exception of spherical aberration, the toric SCL were successful in significantly reducing uncorrected higher-order aberrations.
authors.affiliation: Faculty of Life Sciences, The University of Manchester, Manchester, UK.
authors.forename: Amit
authors.initials: A
authors.lastname: Jinabhai
authors.forename: Hema
authors.initials: H
authors.lastname: Radhakrishnan
authors.forename: Cindy
authors.initials: C
authors.lastname: Tromans
authors.forename: Clare
authors.initials: C
authors.lastname: O'Donnell
mesh_terms: D000328:Adult; D003261:Contact Lenses; D003263:Contact Lenses, Hydrophilic; D015350:Contrast Sensitivity / Q000502:physiology; D019781:Corneal Topography / Q000379:methods; D057108:Corneal Wavefront Aberration / Q000209:etiology / Q000503:physiopathology; D005139:Eyeglasses; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications / Q000473:pathology / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult