Regional Biomechanical Properties of Human Sclera After Cross-linking by Riboflavin/Ultraviolet A

Abstract

Equatorial and posterior human sclera may be enhanced by CXL with riboflavin/ultraviolet A irradiation. Equatorial scleral CXL may be a good choice for the treatment of progressive myopia. Because of its safety and efficacy, 20 minutes of riboflavin infiltration before CXL is recommended.

Dose‐dependent collagen cross‐linking of rabbit scleral tissue by blue light and riboflavin treatment probed by dynamic shear rheology

“…However, the versatile technology of dynamic shear rheology offers several possibilities, including additional opportunities of data acquisition or small strains, in comparison with conventional material tester equipment using strain and stress strengths close to the point of complete material rupture. Employing a material tester in other studies, the elastic modulus was calculated at strains of 8% (Wollensak & Spoerl 2004;Wang et al 2012) or even of 50% (Wollensak et al 2005). In this study, we could show that the elastic modulus of normal scleral tissue already decreases at these strain levels and the viscous properties become more prominent.…”

“…A similar increase of the stiffness (approx. factor 1.3-2.0 at 3 mW/cm 2 UVA light) was observed in isolated human sclera stripes, whereas treatment of isolated porcine sclera increased its stiffness by a factor of 2.6 (Wollensak & Spoerl 2004;Wang et al 2012). Differences of the efficiency of the cross-linking treatment might be due to differences of the used wavelength, irradiation time and the resulting different cumulative surface energies, species-and/or age-specific scleral tissue properties, as well as due to different measurement methodologies.…”

“…Many studies characterizing biomechanical properties of scleral tissue were performed with material tester, and these devices provide useful information about the elastic properties of the material (McBrien & Gentle 2003;Wollensak & Spoerl 2004;Iseli et al 2008;Wang et al 2012). However, the versatile technology of dynamic shear rheology offers several possibilities, including additional opportunities of data acquisition or small strains, in comparison with conventional material tester equipment using strain and stress strengths close to the point of complete material rupture.…”

“…Some studies investigated the effects of various riboflavin instilling times (Wang et al 2012) or different UVA light irradiation times on the biomechanical properties of scleral tissue with one UVA light intensity (Zhang et al 2013). However, data neither about blue light energy-dependent changes of scleral stiffness nor about treatment-induced changes of scleral tissue structure, including possible damaging effects, are available.…”

“…Therefore, various approaches were suggested to stiffen the biomechanically weakened scleral tissue by collagen cross-linking (Wollensak & Spoerl 2004;Wang et al 2012), and these approaches were critically discussed (Elsheikh & Phillips 2013). Collagen cross-linking either by application of substances (e.g.…”