Non-invasive mechano-chemical profiling of Delefilcon A contact lenses by Brillouin-Raman microspectroscopy

Water-gradient contact lenses represent a promising strategy for improving comfort and surface wettability, owing to their distinctive structural design. These lenses consist of a silicone hydrogel core which gradually transitions into a superficial hydrogel layer. While this soft, high-water content surface layer is expected to improve the wearing experience, it also raises concerns about the material’s homogeneity and durability under physiological stresses. In this work, we demonstrate the application of Brillouin-Raman microspectroscopy, a non-invasive and label-free spectroscopic method, for characterizing the chemical and viscoelastic properties of these lenses. Measurements on hydrated Delefilcon A lenses are presented as a proof of concept.