Abstract
Purpose :
Lens biomechanical property changes contribute to the development of presbyopia. However, methods for measuring lens biomechanical properties are still in their infancy and have not progressed beyond linear elasticity. In the present study, we utilize multiple loading modalities (spinning and compression) in conjunction with inverse finite element analysis (iFEA) to enable more rigorous characterization of the lens, including incorporation of nonlinear, viscoelastic constitutive models.
Methods :
Porcine eyes were obtained from a local abattoir and lenses dissected within 2 hours post mortem. Lenses were decapsulated, then subjected to spinning and compression testing. These experiments controlled both load and loading rate. Photographs of the lens were taken at equally spaced loading increments, then processed to allow construction of a finite element model for each lens. Simulations were performed iteratively to estimate the biomechanical properties.
Results :
Previous experiments have found that the young porcine lens has a biomechanical property gradient (Reilly & Ravi, J. Biomech. Eng. 2009; 131(4):044502). Our method was able to resolve this gradient, producing results in line with what we have previously measured.
Conclusions :
The present approach has several key advantages over single-mode biomechanical tests. Multimode testing is essential for accurate calibration of constitutive models, and time-resolved loading is critical for assessing viscoelastic properties. By combining dynamic, automated methods for both compression and spinning, we have devised a method by which viscoelastic constitutive models may be accurately calibrated.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.