title: Factors Influencing Progression of Keratoconus 2 Years After Corneal Collagen Cross-Linking in Pediatric Patients.
abstract: OBJECTIVE
  To assess the preoperative patient characteristics that may predict outcomes of keratoconus 2 years after corneal collagen cross-linking (CXL) in pediatric patients with keratoconus.
  
  
  METHODS
  This retrospective study included 72 eyes of 52 consecutive patients with keratoconus under the age of 18 with 2-year follow-up after CXL. Subgroup analysis and cutoff values were determined as per age (<14 and ≥14 years), sex, baseline uncorrected and corrected distance visual acuities (UCVA, CDVA; <0.8 and ≥0.8 logMAR), topographic cone location (central and paracentral), maximum keratometry (K-max, <54 and ≥54 diopters), and corneal thickness at the thinnest point (thCT) (<450 and ≥450 μm) to evaluate the associations between preoperative patient characteristics and outcomes of CXL treatment in terms of K-max. Postoperative progression in K-max was defined as steepening of 1.0 diopter or more.
  
  
  RESULTS
  Average age of patients was 14.8 ± 2.2 (9-17) years. After 2 years, the mean UCVA significantly improved and the mean thCT significantly decreased in all patients (P = 0.023, P < 0.001, respectively). The K-max in patients with paracentral cones and/or with thCT less than 450 μm were more likely to progress (cone location: P = 0.023, odds ratio = 3.21, 95% confidence interval, 1.17-8.72; thCT: P = 0.008, odds ratio = 4.54, 95% confidence interval, 1.46-14.14). Age, sex, baseline UCVA, CDVA, and K-max did not present any significant effect on progression of CXL after treatment (P > 0.05 for all variables).
  
  
  CONCLUSIONS
  In pediatric patients with keratoconus, cone location and the baseline thinnest corneal thickness seem to affect the success rate of CXL treatment after 2-year follow-up.
authors.affiliation: *Department of Ophthalmology, Ankara Ataturk Training and Research Hospital, Ankara, Turkey;†Department of Ophthalmology, Hacettepe University, Ankara, Turkey; and‡Department of Ophthalmology, Ankara Ataturk Training and Research Hospital, Yildirim Beyazit University, Ankara, Turkey.
authors.forename: Ozge
authors.initials: O
authors.lastname: Sarac
authors.forename: Mehtap
authors.initials: M
authors.lastname: Caglayan
authors.forename: Hasan Basri
authors.initials: HB
authors.lastname: Cakmak
authors.forename: Nurullah
authors.initials: N
authors.lastname: Cagil
mesh_terms: D000293:Adolescent; D002648:Child; D003094:Collagen / Q000378:metabolism*; D003319:Corneal Stroma / Q000378:metabolism*; D019781:Corneal Topography; D003432:Cross-Linking Reagents; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis* / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011183:Postoperative Complications; D012189:Retrospective Studies; D012256:Riboflavin / Q000627:therapeutic use; D012307:Risk Factors; D014466:Ultraviolet Rays; D014792:Visual Acuity / Q000502:physiology
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin