Abstract:
"Inverse computational analysis of in vivo corneal elastic modulus change after collagen crosslinking for keratoconus"
Corneal collagen crosslinking (CXL) is a biomechanical intervention designed to arrest keratoconus progression by stiffening the corneal stroma. In this study, patient-specific three-dimensional finite element (FE) models of 16 keratoconic eyes were generated from pre-treatment Scheimpflug topography and in vivo intraocular pressure (IOP) data. A reduced-polynomial hyperelastic material formulation captured baseline corneal behavior, including a cylindrical “weak zone” to mimic ectatic regions. Simulated CXL was modeled by spatially varying the strain energy parameters within a 9 mm treatment zone, assuming uniform anterior stiffening and exploring depth-dependent attenuation effects. An inverse Levenberg–Marquardt optimization minimized the difference between FE-predicted and post-treatment anterior surface tangential curvatures, yielding estimates of the elastic modulus increase (f = α′/α). Across all eyes and follow-up intervals (3–15 months), mean stiffening was 110.8 ± 48.1%, with interpatient variability driven by geometric and material factors. Sensitivity analyses showed that increasing the sclera-to-cornea modulus ratio slightly reduces estimated stiffening, while modeling UV attenuation concentrates stiffening in anterior stromal layers. Longitudinal trends revealed that most eyes stabilize by one year, though individual responses vary. These biomechanics-focused insights underscore the utility of inverse FE methods for quantifying in vivo corneal material changes, guiding personalized CXL protocols and advancing mechanistic understanding of load-bearing restoration in ectatic disease.
