title: Masking of irregular corneal topography with contact lenses.
abstract: OBJECTIVE
  We examined the effectiveness of various types of contact lenses in masking irregular corneal topography using videokeratoscopy, residual aberrations, and measurement of visual acuity.
  
  
  METHODS
  Thirteen subjects with differing degrees of keratoconus were recruited. Four types of soft lenses were used that varied in both thickness and water content, along with a rigid gas permeable (RGP) and a flexible gas permeable contact lens.
  
  
  RESULTS
  RGP contact lenses provided the best visual acuity and the least residual aberrations. Flexible gas permeable lenses showed a reasonable masking of corneal distortion but did not provide the expected improvement in visual acuity. Soft contact lenses provided marginally better visual acuity than spectacle correction, but the level of residual aberrations was still high, even for relatively thick soft lenses (up to 0.2 mm). A significant correlation existed between the regularity of the front surface of the contact lenses on the eye and visual acuity in low illumination.
  
  
  CONCLUSIONS
  Among the currently available contact lens materials, RGP lenses provide the best visual performance for subjects with keratoconus.
authors.affiliation: Centre for Eye Research, School of Optometry, Queensland University of Technology, Australia.
authors.forename: M
authors.initials: M
authors.lastname: Griffiths
authors.forename: K
authors.initials: K
authors.lastname: Zahner
authors.forename: M
authors.initials: M
authors.lastname: Collins
authors.forename: L
authors.initials: L
authors.lastname: Carney
mesh_terms: D000328:Adult; D003261:Contact Lenses; D003263:Contact Lenses, Hydrophilic; D003315:Cornea / Q000473:pathology*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000473:pathology* / Q000503:physiopathology* / Q000628:therapy; D008029:Lighting; D008297:Male; D014792:Visual Acuity / Q000502:physiology