title: Corneal cross-linking for treatment of progressive keratoconus in various age groups.
abstract: OBJECTIVE
  To compare the effect of corneal cross-linking (CXL) for keratoconus in various age groups and to investigate the influence of the topographic cone location on the outcome of CXL.
  
  
  METHODS
  This cohort study included 95 patients (119 eyes) diagnosed as having progressive keratoconus who underwent epithelium-off standard protocol CXL from January 2010 through May 2012. For statistical analysis, patients were divided into three age groups: pediatric patients (< 18 years), adolescent patients (18 to 26 years), and adults (> 26 years). Visual acuity and refraction, topography, intraocular pressure, and endothelial cell counts were recorded preoperatively and postoperatively.
  
  
  RESULTS
  Topographic cones were located more centrally in pediatric corneas (0.85 ± 0.66 mm) compared to adolescent corneas (1.49 ± 0.76 mm, P = .002) and adult corneas (1.86 ± 0.99 mm, P < .001). Pediatric corneas flattened 1 year after CXL by a mean of 1.8 diopters (D), compared to 1.1 D in the other age groups. Central cones (0 to 1 mm) were steeper (62.3 ± 8.3 D) before treatment than peripheral cones (3 to 4 mm) (55.9 ± 8.9 D). One year after CXL, corrected distance visual acuity improved in all age groups, with the highest improvement in pediatric eyes (-0.23 ± 0.40 logMAR, P = .044).
  
  
  CONCLUSIONS
  Before CXL, cones of pediatric keratoconic corneas were located more centrally than in the two older age groups. After CXL, pediatric corneas showed more corneal flattening and more corrected distance visual acuity improvement. Pediatric CXL was equally safe compared to adolescent and adult CXL.
authors.forename: Nienke
authors.initials: N
authors.lastname: Soeters
authors.forename: Rikkert
authors.initials: R
authors.lastname: van der Valk
authors.forename: Nayyirih G
authors.initials: NG
authors.lastname: Tahzib
mesh_terms: D000293:Adolescent; D000328:Adult; D000375:Aging / Q000502:physiology*; D002452:Cell Count; D002648:Child; D003094:Collagen / Q000378:metabolism; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D018450:Disease Progression; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000188:drug therapy* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012029:Refraction, Ocular / Q000502:physiology; D012256:Riboflavin / Q000627:therapeutic use*; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin