title: Long-term follow-up of riboflavin/ultraviolet A (370 nm) corneal collagen cross-linking to halt the progression of keratoconus.
abstract: OBJECTIVE
  To determine long-term efficacy of riboflavin/ultraviolet A corneal cross-linking (CXL).
  
  
  METHODS
  Thirty patients (30 eyes) who had undergone CXL following epithelial removal 4-6 years previously were examined.
  
  
  RESULTS
  At 1-year mean, spherical equivalent error (SEQ) increased by +0.72 dioptres (D) (p<0.002), corrected distance visual acuity (CDVA) improved (p<0.005), mean simulated keratometry (Sim K) reduced by 0.27D (p<0.04), cone apex power (CAP) reduced by 0.4D (p<0.02), and secondary astigmatism improved (p<0.03) compared with preoperative values. At 4-6 years, mean SEQ increased by +0.82D (p<0.001), CDVA improved (p<0.03), mean Sim K reduced by 0.84D (p<0.00001), CAP reduced by 1.16D (p<0.0005), and root mean square (RMS) (p<0.0001), coma (p<0.0001), secondary astigmatism (p<0.005) and pentafoil (p<0.05) decreased compared with preoperative values. At 4-6 years, mean Sim K reduced by 0.59D (p<0.0005), CAP reduced by 0.76D (p<0.02), RMS (p<0.001), coma (p<0.002) and secondary astigmatism (p<0.02) reduced and central pachymetry increased (p<0.05) compared with 1 year. No treated eyes progressed. None lost >1 line of CDVA. Seven untreated fellow eyes progressed.
  
  
  CONCLUSIONS
  CXL is an effective and safe treatment with up to 4-6 years follow-up. Improvements in topographic and wave-front parameters evident at 1 year continue to improve at 4-6 years.
authors: Department of Ophthalmology, Keratoconus Research Insitute, St. Thomas' Hospital, London SE1 7EH, UK. davidobrart@aol.com
authors: David P S
authors: DP
authors: O'Brart
authors: Tsong Q
authors: TQ
authors: Kwong
authors: Parul
authors: P
authors: Patel
authors: Robert J
authors: RJ
authors: McDonald
authors: Naomi A
authors: NA
authors: O'Brart
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D002648:Child; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D003646:Debridement; D018450:Disease Progression; D019573:Epithelium, Corneal / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D017319:Photosensitizing Agents / Q000627:therapeutic use*; 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