title: Corneal biomechanical properties and anterior segment parameters in forme fruste keratoconus.
abstract: OBJECTIVE
  To evaluate the sensitivity and specificity of corneal biomechanical metrics, anterior segment data, and a combination model in differentiating forme fruste keratoconus (FFK) from normal corneas.
  
  
  METHODS
  A total of 50 FFK eyes were identified by calculation of the KISA index and recruited FFK group. Results were compared with 50 normal eyes (NG group) randomly selected from 50 patients. The following parameters were evaluated for their diagnostic capacity by evaluation of their receiver operating characteristic curves (ROC): corneal hysteresis (CH), corneal resistance factor (CRF), corneal astigmatism (Cyl), anterior chamber depth (ACD), corneal volume (CV) at 3 mm (CV3) and at 5 mm (CV5), maximum posterior elevation value (PEL), central corneal thickness (CCT), thinnest corneal thickness (TCT) and its coordinates (TCTx, TCTy ), the ratio TCT/CCT, pachymetric progression indexes (PPImin, PPIavg, and PPImax), and Ambrósio's relational thickness (ARTmin, ARTavg, and ARTmax). Logistic regression was attempted for identification of a combined diagnostic model.
  
  
  RESULTS
  Significant differences were detected in all studied parameters except the Cyl, ACD, TCTx, and CV. Among individual parameters, the highest predictive accuracy was for ARTavg (area under the curve [AUC] 95.4%, sensitivity 90%, specificity 88.9%) and TCT (AUC 95.3%, sensitivity 90.9%, specificity 89%). Sufficient predictive accuracy (AUC 99.4%, sensitivity 98.8%, specificity 94.6%) was identified in a diagnostic model that combined the CRF, ARTavg, and PEL parameters.
  
  
  CONCLUSIONS
  None of the individual parameters provide sufficient diagnostic capacity in FFK. However, diagnostic models that combine biomechanical and tomographic data seem to provide high accuracy in differentiating FFK from normal corneas.
authors.affiliation: Eye Institute of Thrace, Democritus University - Greece; and Department of Ophthalmology, University Hospital of Alexandroupolis - Greece.
authors.forename: Vassilios
authors.initials: V
authors.lastname: Kozobolis
authors.forename: Haris
authors.initials: H
authors.lastname: Sideroudi
authors.forename: Athanassios
authors.initials: A
authors.lastname: Giarmoukakis
authors.forename: Maria
authors.initials: M
authors.lastname: Gkika
authors.forename: Georgios
authors.initials: G
authors.lastname: Labiris
mesh_terms: D000328:Adult; D000869:Anterior Eye Segment / Q000503:physiopathology*; D019540:Area Under Curve; D001696:Biomechanical Phenomena / Q000502:physiology; D003315:Cornea / Q000503:physiopathology*; D019781:Corneal Topography; D018450:Disease Progression; D004548:Elasticity / Q000502:physiology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000503:physiopathology; D008297:Male; D011446:Prospective Studies; D012372:ROC Curve; D012680:Sensitivity and Specificity; D055815:Young Adult