title: In vivo biomechanical changes after corneal collagen cross-linking for keratoconus and corneal ectasia: 1-year analysis of a randomized, controlled, clinical trial.
abstract: OBJECTIVE
  To investigate the in vivo, corneal, biomechanical changes after corneal collagen cross-linking (CXL) using the Ocular Response Analyzer (ORA) in patients with keratoconus and post-laser in situ keratomileusis (LASIK) ectasia.
  
  
  METHODS
  Single-center, prospective, randomized, controlled, clinical trial. After CXL (69 eyes, 46 keratoconus and 23 post-LASIK), corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the ORA and analyzed in a treatment, sham control, and fellow eye control group at baseline and 1, 3, 6, and 12 months.
  
  
  RESULTS
  There were no significant changes in CH (change = 0.05 ± 1.5; P = 0.78) or CRF (change = 0.29 ± 1.4; P = 0.1) at 1 year compared with preoperative values. Changes in CH and CRF were not correlated with changes in clinical outcomes of uncorrected visual acuity, best spectacle-corrected visual acuity, and maximum keratometry. There were no significant changes in CH in the sham or fellow eye control groups (P(sham) = 0.7; P(FE) = 0.3) or CRF (P(sham) = 0.6; P(FE) = 0.72).
  
  
  CONCLUSIONS
  Despite an increase in CRF at one month, there were no statistically significant changes in CH and CRF measurements 1 year after CXL. Development of other in vivo biomechanical metrics would aid in evaluating the corneal response to CXL.
authors: Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus, Teaneck, NJ 07666, USA.
authors: Steven A
authors: SA
authors: Greenstein
authors: Kristen L
authors: KL
authors: Fry
authors: Peter S
authors: PS
authors: Hersh
mesh_terms: D001696:Biomechanical Phenomena / Q000502:physiology*; D003094:Collagen / Q000187:drug effects*; D003315:Cornea / Q000187:drug effects / Q000503:physiopathology*; D003316:Corneal Diseases / Q000188:drug therapy* / Q000503:physiopathology*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004108:Dilatation, Pathologic / Q000188:drug therapy / Q000503:physiopathology; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000503:physiopathology; D020731:Keratomileusis, Laser In Situ; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D014792:Visual Acuity
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin