title: Corneal collagen cross-linking for ectasia after LASIK and photorefractive keratectomy: long-term results.
abstract: OBJECTIVE
  To report the long-term results of corneal collagen cross-linking (CXL) in ectasia after LASIK and photorefractive keratectomy (PRK).
  
  
  METHODS
  Retrospective, interventional cases series.
  
  
  METHODS
  Twenty-six eyes of 26 patients (18 male, 8 female) with postoperative ectasia after LASIK (23 eyes) and PRK (3 eyes) were included with a mean age of 35 ± 9 years at the time of treatment and a mean follow-up of 25 months (range, 12-62 months).
  
  
  METHODS
  All consecutive patients treated with CXL for progressive ectasia after LASIK or PRK at the Institute for Refractive and Ophthalmic Surgery, Zurich, Switzerland between 2004 and 2010 were included.
  
  
  METHODS
  Corrected distance visual acuity (CDVA), maximum keratometry readings (K(max)), minimum radius of curvature (R(min)), and 6 corneal topography indices were assessed in this study.
  
  
  RESULTS
  Mean CDVA before CXL was 0.5 logarithm of the minimum angle of resolution (logMAR) units, which improved to a mean of 0.3 logMAR units (P<0.001). Corrected distance visual acuity improved 1 line or more in 19 cases and remained unchanged in 7 patients. Mean K(max) after CXL of 50.9 ± 4.9 diopters (D) was significantly lower (P<0.001) than mean pre-CXL K(max) of 52.8 ± 5 D. The R(min) after CXL was increased significantly (P = 0.006), whereas the index of surface variance (P = 0.03), the index of vertical asymmetry (P = 0.04), the keratoconus index (P = 0.03), and the central keratoconus index (P = 0.016) were reduced significantly.
  
  
  CONCLUSIONS
  Ectasia after LASIK and PRK was arrested by CXL with stabilization or improvement of CDVA and K(max) after a mean follow-up of 25 months. There were improvements in 4 topography indices, suggesting a more regular corneal surface.
authors.affiliation: Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, Geneva, Switzerland.
authors.forename: Olivier
authors.initials: O
authors.lastname: Richoz
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Mavrakanas
authors.forename: Bojan
authors.initials: B
authors.lastname: Pajic
authors.forename: Farhad
authors.initials: F
authors.lastname: Hafezi
mesh_terms: D000328:Adult; D003094:Collagen / Q000378:metabolism*; D003316:Corneal Diseases / Q000188:drug therapy* / Q000209:etiology / Q000378:metabolism; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004108:Dilatation, Pathologic / Q000188:drug therapy / Q000209:etiology / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy; D018903:Photorefractive Keratectomy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011183:Postoperative Complications; D012189:Retrospective Studies; 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