title: Dose-dependent collagen cross-linking of rabbit scleral tissue by blue light and riboflavin treatment probed by dynamic shear rheology.
abstract: OBJECTIVE
  To determine the visco-elastic properties of isolated rabbit scleral tissue and dose-dependent biomechanical and morphological changes after collagen cross-linking by riboflavin/blue light treatment.
  
  
  METHODS
  Scleral patches from 87 adult albino rabbit eyes were examined by dynamic shear rheology. Scleral patches were treated by riboflavin and different intensities of blue light (450 nm), and the impact on the visco-elastic properties was determined by various rheological test regimes. The relative elastic modulus was calculated from non-treated and corresponding treated scleral patches, and treatments with different blue light intensities were compared.
  
  
  RESULTS
  Shear rheology enables us to study the material properties of scleral tissue within physiological relevant parameters. Cross-linking treatment increased the viscous as well as the elastic modulus and changed the ratio of the elastic versus viscous proportion in scleral tissue. Constant riboflavin application combined with different blue light intensities from 12 mW/cm(2) up to 100 mW/cm(2) increased the relative elastic modulus of scleral tissue by factors up to 1.8. Further enhancement of the applied light intensity caused a decline of the relative elastic modulus. This might be due to destructive changes of the collagen bundle structure at larger light intensities, as observed by histological examination.
  
  
  CONCLUSIONS
  Collagen cross-linking by riboflavin/blue light application increases the biomechanical stiffness of the sclera in a dose-dependent manner up to certain light intensities. Therefore, this treatment might be a suitable therapeutic approach to stabilize the biomechanical properties of scleral tissue in cases of pathological eye expansion.
authors.affiliation: Soft Matter Physics Division, Institute for Experimental Physics I, Department of Physics and Earth Science, Leipzig University, Leipzig, Germany.|Translational Centre for Regenerative Medicine, Leipzig University, Leipzig, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schuldt
authors.affiliation: Translational Centre for Regenerative Medicine, Leipzig University, Leipzig, Germany.|Paul-Flechsig-Institute for Brain Research, Leipzig University, Leipzig, Germany.
authors.forename: Anett
authors.initials: A
authors.lastname: Karl
authors.affiliation: Translational Centre for Regenerative Medicine, Leipzig University, Leipzig, Germany.|Paul-Flechsig-Institute for Brain Research, Leipzig University, Leipzig, Germany.
authors.forename: Nicole
authors.initials: N
authors.lastname: Körber
authors.affiliation: Translational Centre for Regenerative Medicine, Leipzig University, Leipzig, Germany.|Department of Ophthalmology, University Hospital, Leipzig University, Leipzig, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Koch
authors.affiliation: Paul-Flechsig-Institute for Brain Research, Leipzig University, Leipzig, Germany.
authors.forename: Qing
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Soft Matter Physics Division, Institute for Experimental Physics I, Department of Physics and Earth Science, Leipzig University, Leipzig, Germany.
authors.forename: Anatol W
authors.initials: AW
authors.lastname: Fritsch
authors.affiliation: Paul-Flechsig-Institute for Brain Research, Leipzig University, Leipzig, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Reichenbach
authors.affiliation: Department of Ophthalmology, University Hospital, Leipzig University, Leipzig, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Wiedemann
authors.affiliation: Soft Matter Physics Division, Institute for Experimental Physics I, Department of Physics and Earth Science, Leipzig University, Leipzig, Germany.
authors.forename: Josef A
authors.initials: JA
authors.lastname: Käs
authors.affiliation: Translational Centre for Regenerative Medicine, Leipzig University, Leipzig, Germany.|Paul-Flechsig-Institute for Brain Research, Leipzig University, Leipzig, Germany.
authors.forename: Mike
authors.initials: M
authors.lastname: Francke
authors.affiliation: Department of Ophthalmology, University Hospital, Leipzig University, Leipzig, Germany.|Limmat Eye Center, Zürich, Switzerland.
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Iseli
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003094:Collagen / Q000378:metabolism*; D003432:Cross-Linking Reagents; D004307:Dose-Response Relationship, Radiation; D055119:Elastic Modulus / Q000502:physiology*; D008027:Light; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology; D011817:Rabbits; D012212:Rheology; D012256:Riboflavin / Q000494:pharmacology*; D012590:Sclera / Q000187:drug effects* / Q000378:metabolism*
chemical_list: D003432:Cross-Linking Reagents; D017319:Photosensitizing Agents; D003094:Collagen; D012256:Riboflavin
keywords: blue light; collagen cross-linking; rabbit; rheology; sclera