title: Enhanced Combined Tomography and Biomechanics Data for Distinguishing Forme Fruste Keratoconus.
abstract: OBJECTIVE
  To evaluate the performance of the Ocular Response Analyzer (ORA) (Reichert Ophthalmic Instruments, Depew, NY) variables and Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) tomographic parameters in differentiating forme fruste keratoconus (FFKC) from normal corneas, and to assess a combined biomechanical and tomographic parameter to improve outcomes.
  
  
  METHODS
  Seventy-six eyes of 76 normal patients and 21 eyes of 21 patients with FFKC were included in the study. Fifteen variables were derived from exported ORA signals to characterize putative indicators of biomechanical behavior and 37 ORA waveform parameters were tested. Sixteen tomographic parameters from Pentacam HR were tested. Logistic regression was used to produce a combined biomechanical and tomography linear model. Differences between groups were assessed by the Mann-Whitney U test. The area under the receiver operating characteristics curve (AUROC) was used to compare diagnostic performance.
  
  
  RESULTS
  No statistically significant differences were found in age, thinnest point, central corneal thickness, and maximum keratometry between groups. Twenty-one parameters showed significant differences between the FFKC and control groups. Among the ORA waveform measurements, the best parameters were those related to the area under the first peak, p1area1 (AUROC, 0.717 ± 0.065). Among the investigator ORA variables, a measure incorporating the pressure-deformation relationship of the entire response cycle was the best predictor (hysteresis loop area, AUROC, 0.688 ± 0.068). Among tomographic parameters, Belin/Ambrósio display showed the highest predictive value (AUROC, 0.91 ± 0.057). A combination of parameters showed the best result (AUROC, 0.953 ± 0.024) outperforming individual parameters.
  
  
  CONCLUSIONS
  Tomographic and biomechanical parameters demonstrated the ability to differentiate FFKC from normal eyes. A combination of both types of information further improved predictive value. [J Refract Surg. 2016;32(7):479-485.].
authors.forename: Allan
authors.initials: A
authors.lastname: Luz
authors.forename: Bernardo
authors.initials: B
authors.lastname: Lopes
authors.forename: Katie M
authors.initials: KM
authors.lastname: Hallahan
authors.forename: Bruno
authors.initials: B
authors.lastname: Valbon
authors.forename: Isaac
authors.initials: I
authors.lastname: Ramos
authors.forename: Fernando
authors.initials: F
authors.lastname: Faria-Correia
authors.forename: Paulo
authors.initials: P
authors.lastname: Schor
authors.forename: William J
authors.initials: WJ
authors.lastname: Dupps
authors.forename: Renato
authors.initials: R
authors.lastname: Ambrósio
mesh_terms: D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001696:Biomechanical Phenomena; D002648:Child; D003315:Cornea / Q000503:physiopathology*; D063171:Corneal Pachymetry; D019781:Corneal Topography; D003941:Diagnostic Techniques, Ophthalmological; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D014054:Tomography; D055815:Young Adult