The relationship between mechanical properties, ultrastructural changes, and intrafibrillar bond formation in corneal UVA/riboflavin cross-linking treatment for keratoconus

Shao Hsuan Chang, Ashkan Eliasy, Kai Jung Chen, You Ren Ji, Tai Horng Young, Tsung Jen Wang, Colin E. Willoughby, Kevin J. Hamill, Ahmed Elsheikh

Research output: Contribution to journalArticle

5 Citations (Scopus)


PURPOSE: To determine the relationship between mechanical behavior in cross-linked corneas and changes in the corneal ultrastructure after corneal cross-linking (CXL). METHODS: Porcine corneas were treated following the “Dresden” protocol, the current gold standard for clinical treatment, consisting of dropwise application of 0.1% riboflavin in 20% dextran followed by 30 minutes of ultraviolet-A (UVA) irradiation. The effect of CXL was assessed using uniaxial tensile testing, transmission electron microscopy, and Fourier transform infrared spectroscopy, with results compared against corneas treated with each of the treatment solution components individually. RESULTS: UVA/riboflavin cross-linked corneas displayed 28% ± 17% increase in the material tangent modulus compared with dextran treatment alone, and altered collagen architecture within the first 300 µm of stromal depth consisting of 5% increase in the thickness of collagen fibrils, no significant changes to interfibrillar spacing, and an 8% to 12% decrease in number of fibrils per unit area. Fourier transform infrared spectroscopy confirmed formation of interfibrillar bonds (P = .012) induced by UVA-mediated CXL. CONCLUSIONS: The data support a model wherein collagen fibril diameter and structural density are fundamental parameters in defining tissue stiffening following UVA/riboflavin CXL and provide benchmarks against which modifications to the Dresden CXL protocol can be evaluated.

Original languageEnglish
Pages (from-to)264-272
Number of pages9
JournalJournal of Refractive Surgery
Issue number4
Publication statusPublished - Apr 1 2018


ASJC Scopus subject areas

  • Surgery
  • Ophthalmology

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