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Long-term follow-up of riboflavin/ultraviolet A (370 nm) corneal collagen cross-linking to halt the progression of keratoconus
  1. David P S O'Brart1,
  2. Tsong Q Kwong1,
  3. Parul Patel1,
  4. Robert J McDonald1,
  5. Naomi A O'Brart2
  1. 1Department of Ophthalmology, Keratoconus Research Institute, St. Thomas’ Hospital, London, UK
  2. 2School of Optometry, University of Cardiff, Cardiff, Wales
  1. Correspondence to David P S O'Brart, Department of Ophthalmology, Keratoconus Research Insitute, St. Thomas’ Hospital, London SE1 7EH, UK; davidobrart{at}


Aims To determine long-term efficacy of riboflavin/ultraviolet A corneal cross-linking (CXL).

Methods Thirty patients (30 eyes) who had undergone CXL following epithelial removal 4–6 years previously were examined.

Results At 1-year mean, spherical equivalent error (SEQ) increased by +0.72 dioptres (D) (p<0.002), corrected distance visual acuity (CDVA) improved (p<0.005), mean simulated keratometry (Sim K) reduced by 0.27D (p<0.04), cone apex power (CAP) reduced by 0.4D (p<0.02), and secondary astigmatism improved (p<0.03) compared with preoperative values. At 4–6 years, mean SEQ increased by +0.82D (p<0.001), CDVA improved (p<0.03), mean Sim K reduced by 0.84D (p<0.00001), CAP reduced by 1.16D (p<0.0005), and root mean square (RMS) (p<0.0001), coma (p<0.0001), secondary astigmatism (p<0.005) and pentafoil (p<0.05) decreased compared with preoperative values. At 4–6 years, mean Sim K reduced by 0.59D (p<0.0005), CAP reduced by 0.76D (p<0.02), RMS (p<0.001), coma (p<0.002) and secondary astigmatism (p<0.02) reduced and central pachymetry increased (p<0.05) compared with 1 year. No treated eyes progressed. None lost >1 line of CDVA. Seven untreated fellow eyes progressed.

Conclusions CXL is an effective and safe treatment with up to 4–6 years follow-up. Improvements in topographic and wave-front parameters evident at 1 year continue to improve at 4–6 years.

  • Cornea
  • Clinical Trial
  • Treatment Surgery
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