title: Long-Term Results of Phototherapeutic Keratectomy Versus Mechanical Epithelial Removal Followed by Corneal Collagen Cross-Linking for Keratoconus.
abstract: OBJECTIVE
  To compare the long-term visual outcomes of patients with keratoconus treated with either phototherapeutic keratectomy (PTK) or mechanical epithelial removal before corneal collagen cross-linking (CXL) at 1, 3, 6, and 12 months postoperatively.
  
  
  METHODS
  CXL was performed by 1 of 3 surgeons (K.B., W.B.J., or G.M.). Seventeen eyes underwent mechanical epithelial removal before CXL and were consecutively selected after being matched with the 17 eyes in the PTK group for the variables of procedure date, average keratometry, and pachymetry. All cones were central. Manifest refraction spherical equivalent, sphere, cylinder, corrected distance visual acuity (CDVA), and pachymetry were measured and compared preoperatively and in follow-up.
  
  
  RESULTS
  The mean CDVA change in the PTK group at 12 months postoperatively was statistically different from the mean CDVA change in the mechanical group at 12 months postoperatively (P = 0.031). The PTK group had significantly better outcomes in visual acuity 12 months postoperatively than did the mechanical group (P > 0.05). The mean number of lines of improvement in the PTK and mechanical groups were 2.30 ± 0.96 and 0.00 ± 0.33 lines, respectively (P = 0.0036). The mean change between the preoperative and 12 months postoperative manifest refraction spherical equivalent for the PTK and mechanical groups were 0.78 ± 0.65 and 0.17 ± 0.65, respectively (P > 0.05).
  
  
  CONCLUSIONS
  PTK CXL resulted in better visual outcomes in comparison with mechanical epithelial removal CXL 1 year after treatment.
authors.affiliation: *Department of Ophthalmology, University of Ottawa, Ottawa, Ontario, Canada; and †Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Mustafa
authors.initials: M
authors.lastname: Kapasi
authors.forename: Amanpreet
authors.initials: A
authors.lastname: Dhaliwal
authors.forename: George
authors.initials: G
authors.lastname: Mintsioulis
authors.forename: W Bruce
authors.initials: WB
authors.lastname: Jackson
authors.forename: Kashif
authors.initials: K
authors.lastname: Baig
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000378:metabolism*; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D003432:Cross-Linking Reagents; D003646:Debridement; D019573:Epithelium, Corneal / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy / Q000503:physiopathology / Q000601:surgery / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; 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