Biomechanical properties of lenticules in the ReLEx® SMILE® minimally invasive surgery: Do the age and degree of myopia matter?

This study quantified mechanical properties of human corneal stromal lenticules harvested during ReLEx® SMILE® refractive surgery (122 lenticules; ages 17–47 years; stratified by low/moderate/high myopia) to clarify whether age or myopia severity measurably affects stromal biomechanics. Using multiscale testing (AFM nanoindentation, microscale indentation, and macroscale tensile testing), the authors found wide inter-sample dispersion but no consistent differences between the anterior (Bowman’s-side) and posterior (Descemet’s-side) surfaces. Indentation-derived Young’s moduli were broadly similar across age and myopia groups (AFM means ~54–56 kPa; microindenter values generally higher and more variable), and no robust correlation with axial length was observed. In contrast, whole-lenticule tensile testing (high-strain regime) showed significantly lower tensile modulus for moderate/high myopia compared with low myopia, highlighting method-dependent conclusions and reinforcing that technique, scale, hydration, and loading regime strongly influence apparent corneal stiffness.