Abstract
Purpose :
Simulation of accommodation using a Three-Dimensional (3D) Finite Element Model (FEM) incorporating key anatomical structures including the sclera, ciliary muscles, crystalline lens, lens capsule, zonules, and choroid. Then using FEM to simulate accommodation, disaccommodation and predict Central Optical Power (COP) in a virtual ecosystem.
Methods :
A 3D FEM model of the eye was constructed based on current literature, and ocular imaging, histology, and scanning electron microscopy of human cadaver eyes. This complex model contains the structures biologically and mechanically required for biomechanical analysis of changes in total optical power with accommodation. FEM analysis was performed using Ansys’ Mechanical software. Optical power is based on the conventional lens formula (equation (1)) to determine the dioptric power of the crystalline lens. COP = nl − np ra + nl − np rp − t(nl − np) 2 (ra)(rp)(nl) (1) where nl = refractive index of the lens; np = refractive index of the aqueous humour and the vitreous body; ra and rb = anterior and posterior radii of curvature; and t = lens thickness. Simulations were performed demonstrating biomechanical effects and predict COP in young verses presbyopic eyes.
Results :
The FEM demonstrated the dynamic movements of the ciliary muscle, zonules, lens, sclera, choroid, and vitreous during accommodation at various ages. Biomechanical interactions between extralenticular changes and lens shape in accommodated and disaacommodated states were validated. The FEM successfully predicted the COP from 20-year-old eyes to 60-year-old eyes based on lens shape change and dioptric power with statistically significant correlation to experimental data reported in the literature. The utility of the FEM using predictive capabilities is explored in virtual reality using case examples of therapeutic and surgical interventions.
Conclusions :
Utilization of a FEM of the accommodative system allows for a deeper understanding of the mechanism of accommodation and the effects of age. We demonstrated the connection between the age-related parameters of the lens, and extralenticular structures which effect the amplitude of accommodation and COP using numerical analyses in the FEM. To our knowledge, this is the first effort to predict COP at various ages utilizing FEA in young and presbyopic eyes. Our novel FEM shows promise for predictive diagnostics for COP and presbyopic treatments.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.