Three-dimensional characterization of changes in corneal biomechanics due to corneal crosslinking treatment

• Applicant: Professor Dr. Stefan Lang
• Subject Area: Ophthalmology
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 451894178

The biomechanical stability of the cornea is important for optimal vision. Diseases such as keratoconus lead to progressive visual deterioration due to corneal deformation. This progression can be halted by corneal crosslinking, which is designed to increase mechanical stability of the cornea. Meanwhile, different variants of crosslinking (including accelerated crosslinking over shorter periods of time) are available in clinical treatment. We measure the biomechanical properties of the human cornea using nanoindentation. This enables conclusions about the elasticity of the tissue by indenting the cornea. In our previous DFG-funded research project, we were able to show on the one hand that the elastic modulus in keratoconus is lower than in healthy comparative corneas. In another project we characterized the temporal change of the elastic modulus during crosslinking. This showed a linear increase during treatment. In addition, we compared the increase in elastic modulus for common crosslinking schemes. This includes accelerated crosslinking (from 3 mW / cm² up to 30 mW / cm²) and different riboflavin solutions (with dextran, without dextran and hypoosmolar). In a separate project, we were able to significantly improve the measurement variability of the experimental setup by measuring the cornea under physiological pressure conditions. All results were spatially resolved at the surface of the cornea. The effect on the deeper corneal layers remains unclear. There is evidence that the depth effect of crosslinking differs with different treatment protocols due to oxygen availability. The aim of our follow-up project is the three-dimensional characterization of the effect of different crosslinking protocols on the biomechanics of the human cornea. For this purpose, comparative measurements will be performed after crosslinking treatment of the cornea centrally, paracentrally and peripherally at different depths in 100 µm steps. In addition, we plan to further optimize our experimental setup using a flow system.

• DFG Programme: Research Grants
• Co-Investigators: Professor Dr. Thomas Reinhard; Professor Dr. Günther Schlunck