title: Corneal Cross-linking to Halt the Progression of Keratoconus and Corneal Ectasia: Seven-Year Follow-up.
abstract: OBJECTIVE
  To determine long-term efficacy and safety of riboflavin/ultraviolet A corneal cross-linking (CXL).
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Thirty-six patients (36 eyes) who underwent epithelium-off CXL at a University Hospital (Guy's and St Thomas' National Health Service Foundation Trust) 6-8 years previously were examined. The main outcome measures were refractive error, visual acuity, corneal topographic keratometry, ultrasonic pachymetry, and topography-derived corneal wavefront.
  
  
  RESULTS
  At 7 years compared to preoperative values, mean spherical equivalent refractive error (SEQ) increased by +0.78 diopter (D) (P < .005) and mean simulated topographic keratometry (SimK) and mean maximum keratometry (Kmax) reduced by -0.74 D (P < .0001) and -0.91 D (P < .0001), respectively. Uncorrected distance acuity (UCDA) (P < .0005) and corrected distance acuity (CDVA) (P < .0001) had improved and root mean square (RMS) (P < .0005), coma (P < .0005), and secondary astigmatism (P < .005) lessened. At 7 years compared to 1 year, CDVA improved (P < .05); mean SimK (P < .0005) and mean Kmax (P < .005) reduced by -0.45 D and -0.56 D, respectively; and RMS (P < .0005) and coma (P < .0005) decreased. At 7 years compared to 5 years, CDVA improved (P < .05) and trefoil reduced (P < .05). No treated eyes progressed. In 29 initially untreated fellow eyes mean SimK increased by +0.54 D (P < .02), mean Kmax by +0.87 D (P < .05), and refractive astigmatism increased (P < .0005).
  
  
  CONCLUSIONS
  Following corneal cross-linking, improvements in topographic and wavefront parameters evident at 1 year were seen to continue to improve at 5 years and were maintained at 7 years. No treated eyes progressed over the 7-year follow-up period.
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom. Electronic address: davidobrart@aol.com.
authors: David P S
authors: DP
authors: O'Brart
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom.
authors: Parul
authors: P
authors: Patel
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom.
authors: Gerassimos
authors: G
authors: Lascaratos
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom.
authors: Vijay K
authors: VK
authors: Wagh
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom.
authors: Connan
authors: C
authors: Tam
authors: Department of Ophthalmology, St Thomas' Hospital, London, United Kingdom.
authors: Jennifer
authors: J
authors: Lee
authors: School of Optometry, University of Cardiff, Cardiff, United Kingdom.
authors: Naomi A
authors: NA
authors: O'Brart
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000008:administration & dosage*; D004108:Dilatation, Pathologic / Q000188:drug therapy / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D011446:Prospective Studies; D012256:Riboflavin / Q000008:administration & dosage*; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D012256:Riboflavin