title: Characteristics influencing outcomes of corneal collagen crosslinking for keratoconus and ectasia: implications for patient selection.
abstract: OBJECTIVE
  To determine preoperative patient characteristics that may predict topography and visual acuity outcomes of corneal collagen crosslinking (CXL).
  
  
  METHODS
  Cornea and refractive surgery practice.
  
  
  METHODS
  Cohort study.
  
  
  METHODS
  Crosslinking was performed in eyes with keratoconus or corneal ectasia. Multiple regression and odds ratio analyses were performed to determine independent predictors of changes in topography-derived maximum keratometry (K) and corrected distance visual acuity (CDVA) 1 year postoperatively. Preoperative characteristics included sex, age, uncorrected distance visual acuity (UDVA), CDVA, maximum keratometry (K), corneal thickness, corneal haze, disease group, and cone location. Postoperative improvement in maximum K was defined as flattening of 2.0 diopters (D) or more and worsening as steepening of 1.0 D or more. Improvement in CDVA was defined as a gain of 2 lines or more and worsening as a loss of 1 line or more.
  
  
  RESULTS
  The study comprised 104 eyes (66 keratoconus; 38 corneal ectasia). Eyes with a preoperative CDVA of 20/40 or worse were 5.9 times (95% confidence interval [CI], 2.2-6.4) more likely to improve 2 Snellen lines or more. Eyes with a maximum K of 55.0 D or more were 5.4 times (95% CI, 2.1-14.0) more likely to have topographic flattening of 2.0 D or more. No preoperative characteristics significantly predicted worsening of visual acuity or corneal topography.
  
  
  CONCLUSIONS
  Patients with worse preoperative CDVA and higher K values, particularly with a CDVA of 20/40 or worse or a maximum K of 55.0 D or more, were most likely to have improvement after CXL. No preoperative characteristics were predictive of CXL failure.
authors.affiliation: Cornea and Laser Eye Institute-Hersh Vision Group, CLEI Center for Keratoconus, Teaneck, and the Department of Ophthalmology, UMDNJ New Jersey Medical School, Newark, New Jersey 07666, USA.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Greenstein
authors.forename: Peter S
authors.initials: PS
authors.lastname: Hersh
mesh_terms: D015331:Cohort Studies; D003094:Collagen / Q000378:metabolism*; D003319:Corneal Stroma / Q000378:metabolism*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004108:Dilatation, Pathologic / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D018579:Patient Selection; D010778:Photochemotherapy; D018903:Photorefractive Keratectomy; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D012256:Riboflavin / Q000627:therapeutic use*; D016896:Treatment Outcome; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin