title: Refractive improvements and safety with topography-guided corneal crosslinking for keratoconus: 1-year results.
abstract: To assess the refractive improvements and the corneal endothelial safety of an individualised topography-guided regimen for corneal crosslinking in progressive keratoconus.
  
  
  
  An open-label prospective randomised clinical trial was performed at the Department of Clinical Sciences, Ophthalmology, Umeå University Hospital, Umeå, Sweden. Thirty-seven patients (50 eyes) with progressive keratoconus planned for corneal crosslinking were included. The patients were randomised to topography-guided crosslinking (photorefractive intrastromal crosslinking (PiXL); n=25) or uniform 9 mm crosslinking (corneal collagen crosslinking (CXL); n=25). Visual acuity, refraction, keratometry (K1, K2 and Kmax) and corneal endothelial morphometry were assessed preoperatively and at 1, 3, 6 and 12 months postoperatively. The PiXL treatment involved an asymmetrical treatment zone centred on the area of maximum corneal steepness with treatment energies ranging from 7.2 to 15.0 J/cm2; the CXL treatment was a uniform 9 mm 5.4 J/cm2pulsed crosslinking. The main outcome measures were changes in refractive errors and corneal endothelial cell density.
  
  
  
  The spherical refractive errors decreased (p<0.05) and the visual acuity improved (p<0.01) at 3, 6 and 12 months after PiXL, but not after CXL. The between-groups differences, however, were not significant. K2 and Kmaxdecreased at 3, 6 and 12 months after PiXL (p<0.01), but not after CXL (p<0.01 when comparing the two treatments). No corneal endothelial cell loss was seen after either treatment.
  
  
  
  Individualised topography-based crosslinking treatment centred on the ectatic cone has the potential to improve the corneal shape in keratoconus with decreased spherical refractive errors and improved visual acuity, without damage to the corneal endothelium.
  
  
  
  NCT02514200, Results.
authors.affiliation: Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Nordström
authors.affiliation: Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Schiller
authors.affiliation: Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.
authors.forename: Anneli
authors.initials: A
authors.lastname: Fredriksson
authors.affiliation: Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Behndig
mesh_terms: D000293:Adolescent; D000328:Adult; D003094:Collagen / Q000627:therapeutic use; D003315:Cornea / Q000187:drug effects / Q000473:pathology*; D019781:Corneal Topography / Q000379:methods*; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000188:drug therapy* / Q000473:pathology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010778:Photochemotherapy / Q000379:methods*; D011446:Prospective Studies; D020127:Recovery of Function; D012029:Refraction, Ocular / Q000502:physiology*; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult
chemical_list: D003432:Cross-Linking Reagents; D003094:Collagen
keywords: Cornea; Degeneration; Optics and Refraction