title: Discriminant Value of Custom Ocular Response Analyzer Waveform Derivatives in Forme Fruste Keratoconus.
abstract: OBJECTIVE
  To evaluate the performance of corneal hysteresis (CH), corneal resistance factor (CRF), 37 Ocular Response Analyzer (ORA) waveform parameters, and 15 investigator-derived ORA variables in differentiating forme fruste keratoconus (KC) from normal corneas.
  
  
  METHODS
  Case-control study.
  
  
  METHODS
  Seventy-eight eyes of 78 unaffected patients and 21 topographically normal eyes of 21 forme fruste KC patients with topographically manifest KC in the contralateral eye were matched for age, the thinnest point of the cornea, central corneal thickness, and maximum keratometry. Fifteen candidate variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior, and 37 waveform parameters were tested. Differences between groups were assessed by the Mann-Whitney test. The area under the receiver operating characteristic curve (AUROC) was used to compare the diagnostic performance.
  
  
  RESULTS
  Ten of 54 parameters reached significant differences between the groups (Mann-Whitney test, P < .05). Neither CRF nor CH differed significantly between the groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area, and p1area1 (AUROC, 0.714 ± 0.064 and 0.721 ± 0.065, respectively). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle performed best (hysteresis loop area, AUROC, 0.694 ± 0.067).
  
  
  CONCLUSIONS
  Waveform-derived ORA parameters, including a custom measure incorporating the pressure-deformation relationship of the entire response cycle, performed better than traditional CH and CRF parameters in differentiating forme fruste KC from normal corneas.
authors.affiliation: Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Hospital de Olhos de Sergipe, Aracaju, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil. Electronic address: dr.allanluz@gmail.com.
authors.forename: Allan
authors.initials: A
authors.lastname: Luz
authors.affiliation: Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil.
authors.forename: Bernardo
authors.initials: B
authors.lastname: Lopes
authors.affiliation: Cole Eye Institute, Cleveland Clinic; and Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio.
authors.forename: Katie M
authors.initials: KM
authors.lastname: Hallahan
authors.affiliation: Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil.
authors.forename: Bruno
authors.initials: B
authors.lastname: Valbon
authors.affiliation: Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil.
authors.forename: Bruno
authors.initials: B
authors.lastname: Fontes
authors.affiliation: Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Paulo
authors.initials: P
authors.lastname: Schor
authors.affiliation: Cole Eye Institute, Cleveland Clinic; and Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland, Ohio.
authors.forename: William J
authors.initials: WJ
authors.lastname: Dupps
authors.affiliation: Department for Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil; Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil; Instituto de Olhos Renato Ambrósio and Visare Personal Laser, Rio de Janeiro, Brazil.
authors.forename: Renato
authors.initials: R
authors.lastname: Ambrósio
mesh_terms: D000328:Adult; D019540:Area Under Curve; D001251:Astigmatism / Q000503:physiopathology; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003315:Cornea / Q000503:physiopathology*; D063171:Corneal Pachymetry; D019781:Corneal Topography; D003941:Diagnostic Techniques, Ophthalmological; D004108:Dilatation, Pathologic / Q000175:diagnosis / Q000503:physiopathology; D016002:Discriminant Analysis; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D012372:ROC Curve; D055815:Young Adult