title: Screening for Keratoconus With New Dynamic Biomechanical In Vivo Scheimpflug Analyses.
abstract: OBJECTIVE
  To improve keratoconus (KC) screening with new in vivo biomechanical Scheimpflug analyses.
  
  
  METHODS
  After adjusting for intraocular pressure and corneal thickness, predefined static and new dynamic Scheimpflug curve analyses [Pentacam HR and Corvis ST (CST); Oculus] of 87 normal eyes, 27 subclinical KC eyes, 42 suspected KC, and 65 manifest KC eyes were reviewed retrospectively. A t test (for a normal distribution), Wilcoxon matched-pairs test (if not normally distributed), and receiver operating characteristics were used to test for statistically significant differences between these groups. In addition, new dynamic curve analyses were performed to analyze corneal dynamics throughout the entire response to the CST air puff impulse.
  
  
  RESULTS
  Comparing normal and KC-suspect eyes, the parameters A1 length, A2 length, radius of the inward-bended cornea, and deflection length at the highest concavity revealed statistically significant differences. In addition, the newly calculated "applanation length level" and "deflection length level" demonstrated consistently increasing differences with increasing statistical significance between normal eyes and those with advancing KC stages. However, when comparing normal and subclinical KC eyes, none of the analyzed parameters demonstrated statistically significant differences.
  
  
  CONCLUSIONS
  In vivo biomechanical analyses (CST) at their current state only marginally improve KC screening protocols. Newly generated parameters such as the applanation length level and deflection length level might further improve early KC screening.
authors.affiliation: *Department of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; †zentrumsehstärke, Hamburg, Germany; and ‡Care-Vision Germany, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Steinberg
authors.forename: Toam
authors.initials: T
authors.lastname: Katz
authors.forename: Kristina
authors.initials: K
authors.lastname: Lücke
authors.forename: Andreas
authors.initials: A
authors.lastname: Frings
authors.forename: Vasyl
authors.initials: V
authors.lastname: Druchkiv
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Linke
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003315:Cornea / Q000503:physiopathology*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D004548:Elasticity / Q000502:physiology; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis*; D010781:Photography / Q000379:methods*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult