title: Collagen cross-linking effect on progressive keratoconus in patients younger than 18 years of age: A clinical trial.
abstract: BACKGROUND
  Keratoconus is a bilateral non-inflammatory corneal disease. Collagen cross-linking (CXL) is a new treatment option for the disease that uses ultraviolet A light irradiation and riboflavin administration. The aim of this study is to evaluate the effect of CXL on corneal topographic and refractive values in patients with keratoconus younger than 18 years of age.
  
  
  METHODS
  For the clinical trial study, 37 patients (64 eyes) younger than 18 years of age with progressive keratoconus were included. Age, sex, family history of keratoconus, and history of allergic disorders and eye rubbing were recorded. Refractive, topographic, and topometric indices were evaluated before and 12 months after the CXL with 3mW for 30 minutes.
  
  
  RESULTS
  Mean age (±SD) of the patients was 15.83 ± 1.53 years; 26 (70.3%) of the 37 patients were male. Fourteen (37.8%) had positive family history of keratoconus, 11 (29.7%) had history of allergic disorders, and 15 (40.5%) had positive history of eye rubbing. Of the refractive values, cylinder value decreased significantly from -4.50 ± 0.29 to -4.11 ± 0.28 (P = 0.001). Also, the logarithm of minimal angle of resolution (logMAR) uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) improved significantly 12 months after CXL (P = 0.012 and 0.001, respectively). Maximum keratometry before and after the operation was 53.82 ± 0.72 and 53.33 ± 0.72, respectively (P = 0.018). Differences for simulated K values, the thinnest cornea pachymetry, keratoconus index (KI), index of highest asymmetry (IHA), and index of highest decentration (IHD) before and 12 months after the CXL were statistically significant (P = 0.015, 0.034, <0.001, 0.017, 0.019, and 0.004, respectively).
  
  
  CONCLUSIONS
  CXL improves the refractory, topographic, and topometric indices in patients with keratoconus younger than 18 years of age.
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Alireza
authors.initials: A
authors.lastname: Peyman
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Kamali
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Maral
authors.initials: M
authors.lastname: Khushabi
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Kobra
authors.initials: K
authors.lastname: Nasrollahi
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Kargar
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Taghaodi
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Hasan
authors.initials: H
authors.lastname: Razmjoo
authors.affiliation: Department of Ophthalmology, Isfahan University of Medical Sciences, Isfahan, Iran.
authors.forename: Farhad
authors.initials: F
authors.lastname: Fazel
authors.affiliation: Department of Statistics, Allameh Tabatabai University, Tehran, Iran.
authors.forename: Asiyeh
authors.initials: A
authors.lastname: Salesi
keywords: Collagen cross-linking; progressive keratoconus; refractive value; topography