title: Corneal cross-linking in keratoconus using the standard and rapid treatment protocol: differences in demarcation line and 12-month outcomes.
abstract: OBJECTIVE
  To compare the occurrence rate and depth of the demarcation line and topographical outcome after corneal cross-linking (CXL) for keratoconus using two different treatment protocols.
  
  
  METHODS
  A retrospective analysis of 131 eyes with progressive keratoconus treated with CXL using riboflavin and UV-A was performed. Eyes were treated either with the standard Dresden protocol (30 minutes irradiation, 3 mW/cm(2), UV-XTM 1000) or a rapid protocol (10 minutes irradiation, 9 mW/cm(2), UV-XTM 2000). The presence and depth of the corneal demarcation line was assessed with an anterior segment optical coherence tomography device 1 month after CXL by a masked observer. Corneal topography and tomography was performed at baseline and at 12-month follow-up with Pentacam and the TMS (Topographic Modeling System) device.
  
  
  RESULTS
  In the standard protocol group, 76.5% (62/81) of treated corneas revealed a demarcation line 1 month after CXL, whereas such a demarcation line was observed in only 22% (11/50) of eyes treated with the rapid protocol (P < 0.0001). The demarcation line was significantly more superficial in the rapid protocol group (P = 0.004). Corneal topography values between baseline and 12 months after CXL showed a mean change of -0.76 diopters (D) in Kmax (SD ± 2.7) in the standard protocol group versus a mean change of +0.72 D in Kmax (SD ± 1.5) in the rapid protocol (P = 0.007).
  
  
  CONCLUSIONS
  The rapid CXL protocol negatively influences the occurrence and depth of the demarcation line 1 month after CXL. Our results show a negative effect on the topographical outcome 1 year after CXL.
authors.affiliation: Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Sara
authors.initials: S
authors.lastname: Brittingham
authors.affiliation: Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Tappeiner
authors.affiliation: Department of Ophthalmology, Inselspital, University of Bern, Bern, Switzerland.
authors.forename: Beatrice E
authors.initials: BE
authors.lastname: Frueh
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000175:diagnosis / Q000188:drug therapy*; D008297:Male; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011446:Prospective Studies; D013997:Time Factors; D041623:Tomography, Optical Coherence; D016896:Treatment Outcome; D014792:Visual Acuity
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents
keywords: cornea; corneal topography; cross-linking; demarcation line; keratoconus; rapid protocol; riboflavin UV-A treatment; standard Dresden protocol