title: Different Topographic Response Between Mild to Moderate and Advanced Keratoconus After Accelerated Collagen Cross-linking.
abstract: OBJECTIVE
  To evaluate the clinical and topographic effects after accelerated corneal collagen cross-linking (CXL) in keratoconus.
  
  
  METHODS
  This was a prospective interventional study in 25 eyes of 24 Asian patients with keratoconus, where 10 eyes in group 1 had mild to moderate keratoconus with the steepest keratometry reading (Kmax) < 58 diopters (D), and 15 eyes in group 2 had advanced keratoconus with Kmax ≥ 58.0 D. The patients underwent accelerated CXL with 18 W/cm UV-A light for 5 minutes. Clinical and topographic parameters were obtained before and 1 year after treatment.
  
  
  RESULTS
  Overall, spectacle-corrected distance visual acuity, refraction, average keratometry readings, Kmax, anterior elevation at the apex, and corneal endothelial cell density remained stable (P < 0.102). Posterior elevation at the apex increased at 1 year (P = 0.002). The thinnest pachymetry readings also showed significant reduction (P < 0.001). Kmax in group 1 increased by 1.00 ± 1.63 D (range, -2.2 to 5.4 D; P = 0.012), whereas Kmax in group 2 reduced by 1.69 ± 2.61 D (range, -8.4 to 3.2 D; P = 0.013) at 1 year after accelerated CXL. The change in Kmax between the 2 groups was significantly different (P < 0.001). There was no intergroup difference for the change in other parameters. A significant correlation was found between the preoperative Kmax and postoperative change in Kmax at 1 year (r = -0.648; P < 0.001).
  
  
  CONCLUSIONS
  Accelerated CXL seems to be effective in preventing progression and causing topographic flattening in advanced cases of keratoconus but not as effective in the less progressed counterparts.
authors.affiliation: *Hong Kong Eye Hospital, Hong Kong, China; †Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China; and ‡Hong Kong Eye Hospital, Hong Kong, China.
authors.forename: Tommy C Y
authors.initials: TC
authors.lastname: Chan
authors.forename: Vanissa W S
authors.initials: VW
authors.lastname: Chow
authors.forename: Vishal
authors.initials: V
authors.lastname: Jhanji
authors.forename: Victoria W Y
authors.initials: VW
authors.lastname: Wong
mesh_terms: D000293:Adolescent; D000328:Adult; D002452:Cell Count; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism / Q000473:pathology*; D003319:Corneal Stroma / Q000378:metabolism; D019781:Corneal Topography; D003432:Cross-Linking Reagents; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000145:classification* / Q000188:drug therapy / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; 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