Biomechanical properties of corneal tissue after ultraviolet-A-riboflavin crosslinking

Photodynamic collagen crosslinking (CXL) using ultraviolet-A (UVA) irradiation combined with the photosensitizer riboflavin has been introduced as a new treatment for progressive keratoconus. The results of clinical studies are promising, but the efficacy of the treatment in halting the progression depends on the stability of the induced biomechanical effects. The effects of corneal CXL on corneal rigidity; collagen fiber diameter; and resistance to heat degradation, enzymatic digestion, and swelling due to hydration are reviewed in this paper. The collective results indicate that CXL using UVA and riboflavin enhances the biomechanical properties of the corneal tissue, which remain stable over time. Therefore, this treatment could become the future standard therapy for keratoconus or used to halt the progression of keratoconus and postpone the need for corneal transplantation. The increase in availability and popularity of the CXL technique accentuates the requirement for reliable and accurate techniques for measuring corneal biomechanical properties before and after treatment.