title: Corneal hysteresis and corneal resistance factor in keratoectasia: findings using the Reichert ocular response analyzer.
abstract: OBJECTIVE
  To examine corneal hysteresis (CH) and corneal resistance factor (CRF) in normal and ectatic corneas.
  
  
  METHODS
  CH and CRF were measured using the Reichert Ocular Response Analyzer in patients with clinically diagnosed keratoconus (KC), forme fruste KC (FFKC) and normal eyes.
  
  
  RESULTS
  21 eyes (13 patients) with clinically diagnosed KC and 30 eyes (18 patients) with FFKC were included in the study. Mean CH and CRF in FFKC did not differ from that in pachymetry-matched normal eyes. KC eyes had significantly lower CH and CRF than normal and FFKC eyes.
  
  
  CONCLUSIONS
  A significant overlap in CH and CRF values among the 3 groups was evident. Our findings do not indicate a role for CH and CRF measurement as a single test to aid in the detection of early ectasia. It may be of use when used in conjunction with other parameters such as aberrometry. CH and CRF values may prove to be useful in monitoring ectasia progression.
authors.affiliation: Mater Private Hospital, University College Dublin, Dublin, Ireland.
authors.forename: Caitriona
authors.initials: C
authors.lastname: Kirwan
authors.forename: Donal
authors.initials: D
authors.lastname: O'Malley
authors.forename: Michael
authors.initials: M
authors.lastname: O'Keefe
mesh_terms: D000328:Adult; D003187:Compliance; D003315:Cornea / Q000000981:diagnostic imaging / Q000502:physiology*; D003316:Corneal Diseases / Q000175:diagnosis* / Q000503:physiopathology; D019781:Corneal Topography; D004108:Dilatation, Pathologic / Q000175:diagnosis / Q000503:physiopathology; D004548:Elasticity; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000503:physiopathology; D011446:Prospective Studies; D014463:Ultrasonography