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Comparative evaluation of progression rate in keratoconus before and after collagen crosslinking
  1. Yu Meng Wang1,
  2. Tommy CY Chan1,2,
  3. Marco C Y Yu3,
  4. Vishal Jhanji1,4
  1. 1 Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
  2. 2 Department of Ophthalmology, Hong Kong Eye Hospital, Hong Kong, China
  3. 3 Department of Mathematics and Statistics, Hang Seng Management College, Hong Kong, China
  4. 4 Department of Ophthalmology, UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, USA
  1. Correspondence to Dr Vishal Jhanji, Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong SAR; vishaljhanji{at}


Purpose To compare the rate of disease progression in keratoconus before and after corneal collagen crosslinking (CXL).

Methods 145 eyes were followed without CXL (no-CXL group) for a median duration of 31 months whereas 45 eyes were followed up for 41 months before (pre-CXL) and after (post-CXL) accelerated, epithelium-off crosslinking. Progression was defined based on significant slope found in linear mixed effect models against time. Swept-source optical coherence tomography was used for measurement of anterior steep keratometry, anterior flat keratometry (Ant Kf), anterior average keratometry (Ant Avg K); posterior steep keratometry, posteriorflat keratometry (Post Kf), posterior average keratometry (Post Avg K) and corneal thickness.

Results The patients in pre-CXL group were significantly younger (26.3±5.48 years) compared with the patients in no-CXL group (32.7±10.24 years) (P=0.004). Significant differences were observed during baseline examination for all parameters (P≤0.035) between pre-CXL and no-CXL groups except Ant Cyl and Post Cyl. During observation period, statistically significant differences were noted between pre-CXL and no-CXL groups in the progression rate of Ant Kf, Ant Avg K, Post Kf and Post Avg K (P≤0.045). After CXL, the progression rate in post-CXL group was comparable to that in no-CXL group. All corneal parameters remained stable in no-CXL group throughout the follow-up period.

Conclusions Serial tomographic examination is useful to document disease progression before and after CXL. In our study, a decrease in progression rate of corneal parameters was noted after CXL. In cases with stable corneal parameters over time, careful monitoring can be considered instead of collagen crosslinking.

  • cornea
  • treatment other
  • imaging

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  • Contributors Study design: YW, TCYC, VJ. Data collection: YW. Statistical analysis: MCYY. Writing of manuscript: YW, TCYC, MCYY, VJ. Final approval of manuscript: YW, TCYC, MCYY, VJ. Supervision: VJ.

  • Competing interests None declared.

  • Ethics approval Kowloon Ethics Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Correction notice This article has been corrected since it published Online First. The Corespondence to address has been updated.

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