title: Dynamic Scheimpflug-based assessment of keratoconus and the effects of corneal cross-linking.
abstract: OBJECTIVE
  To evaluate the ability of the Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) to distinguish between normal and keratoconic corneas and detect the possible stiffening effect of corneal cross-linking (CXL) in vivo.
  
  
  METHODS
  A retrospective study including 86 eyes of 86 participants (27 patients with untreated keratoconus, 27 patients with CXL-treated keratoconus, and 32 normal patients). The prospective study included 9 keratoconic eyes measured 24 days before and 97 days after CXL.
  
  
  RESULTS
  The following parameters from the Corvis ST showed a significant difference between keratoconic and normal eyes: intraocular pressure, corneal thickness, first applanation time, highest concavity (HC) radius, HC deformation amplitude, and HC deflection amplitude (analysis of variance, P < .0001). Receiver operating characteristic curve analysis showed the highest area under the curve for HC deflection amplitude (0.942, P < .0001). Prediction intervals for individual measurements within the two groups overlapped considerably. No significant difference was found between the untreated and CXL-treated keratoconus groups (analysis of variance, P > .05). Measurements performed before and after CXL in the same patients showed significant difference in HC deformation amplitude (P = .018), HC time (P = .018), and second applanation time (P = .027).
  
  
  CONCLUSIONS
  Although the corneal deformation characteristics differed between groups of keratoconic and normal eyes, this study showed that the standard parameters of the Corvis ST cannot readily be used for diagnosis of keratoconus in the individual patient or to document the effect of CXL in vivo.
authors: Sashia
authors: S
authors: Bak-Nielsen
authors: Iben B
authors: IB
authors: Pedersen
authors: Anders
authors: A
authors: Ivarsen
authors: Jesper
authors: J
authors: Hjortdal
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism; D003315:Cornea / Q000503:physiopathology*; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D003941:Diagnostic Techniques, Ophthalmological / Q000295:instrumentation*; D004548:Elasticity / Q000502:physiology; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D014466:Ultraviolet Rays; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin