title: A randomized, controlled trial of corneal collagen cross-linking in progressive keratoconus: three-year results.
abstract: OBJECTIVE
  To report the refractive, topographic, and clinical outcomes 3 years after corneal collagen cross-linking (CXL) in eyes with progressive keratoconus.
  
  
  METHODS
  Prospective, randomized controlled trial.
  
  
  METHODS
  One hundred eyes with progressive keratoconus were randomized into the CXL treatment or control groups.
  
  
  METHODS
  Cross-linking was performed by instilling riboflavin 0.1% solution containing 20% dextran for 15 minutes before and during the 30 minutes of ultraviolet A irradiation (3 mW/cm(2)). Follow-up examinations were arranged at 3, 6, 12, 24, and 36 months.
  
  
  METHODS
  The primary outcome measure was the maximum simulated keratometry value (Kmax). Other outcome measures were uncorrected visual acuity (UCVA; measured in logarithm of the minimum angle of resolution [logMAR] units), best spectacle-corrected visual acuity (BSCVA; measured in logMAR units), sphere and cylinder on subjective refraction, spherical equivalent, minimum simulated keratometry value, corneal thickness at the thinnest point, endothelial cell density, and intraocular pressure.
  
  
  RESULTS
  The results from 48 control and 46 treated eyes are reported. In control eyes, Kmax increased by a mean of 1.20±0.28 diopters (D), 1.70±0.36 D, and 1.75±0.38 D at 12, 24, and 36 months, respectively (all P <0.001). In treated eyes, Kmax flattened by -0.72±0.15 D, -0.96±0.16 D, and -1.03±0.19 D at 12, 24, and 36 months, respectively (all P <0.001). The mean change in UCVA in the control group was +0.10±0.04 logMAR (P = 0.034) at 36 months. In the treatment group, both UCVA (-0.15±0.06 logMAR; P = 0.009) and BSCVA (-0.09±0.03 logMAR; P = 0.006) improved at 36 months. There was a significant reduction in corneal thickness measured using computerized videokeratography in both groups at 36 months (control group: -17.01±3.63 μm, P <0.001; treatment group: -19.52±5.06 μm, P <0.001) that was not observed in the treatment group using the manual pachymeter (treatment group: +5.86±4.30 μm, P = 0.181). The manifest cylinder increased by 1.17±0.49 D (P = 0.020) in the control group at 36 months. There were 2 eyes with minor complications that did not affect the final visual acuity.
  
  
  CONCLUSIONS
  At 36 months, there was a sustained improvement in Kmax, UCVA, and BSCVA after CXL, whereas eyes in the control group demonstrated further progression.
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia; Royal Victorian Eye & Ear Hospital, Melbourne, Australia.
authors.forename: Christine
authors.initials: C
authors.lastname: Wittig-Silva
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia; Royal Victorian Eye & Ear Hospital, Melbourne, Australia.
authors.forename: Elsie
authors.initials: E
authors.lastname: Chan
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia; Faculty of Life and Social Sciences, Swinburne University of Technology, Melbourne, Australia.
authors.forename: Fakir M A
authors.initials: FM
authors.lastname: Islam
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia. Electronic address: gsnibson@eyesurgery.com.au.
authors.forename: Tony
authors.initials: T
authors.lastname: Wu
authors.affiliation: Royal Victorian Eye & Ear Hospital, Melbourne, Australia.
authors.forename: Mark
authors.initials: M
authors.lastname: Whiting
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia; Royal Victorian Eye & Ear Hospital, Melbourne, Australia.
authors.forename: Grant R
authors.initials: GR
authors.lastname: Snibson
mesh_terms: D000328:Adult; D002452:Cell Count; D003094:Collagen / Q000378:metabolism*; D063171:Corneal Pachymetry; D003319:Corneal Stroma / Q000378:metabolism*; D019781:Corneal Topography; D003432:Cross-Linking Reagents / Q000627:therapeutic use*; D004728:Endothelium, Corneal / Q000473:pathology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007429:Intraocular Pressure; D007640:Keratoconus / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; 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