Determination Of Central Optical Power Utilizing A Finite Element Model Of Accommodation

To create a Three Dimensional (3D) Finite Element Model (FEM) of accommodation incorporating key anatomical structures including the sclera, ciliary muscles, crystalline lens, lens capsule, zonules, and choroid. We intend to use this FEM to simulate accommodation and disaccommodation and to predict Central Optical Power (COP) in a virtual ecosystem.

A novel proprietary physics-based computer-simulated Finite Element Ecosystem. 

A 3D FEM model was constructed based on current literature, and refined based on imaging, histology, and scanning electron microscopy of human cadaver eyes. This model contains the structures required for biomechanical analysis of changes in total optical power with accommodation. Optical power is based on the 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. Various simulations were performed to demonstrate biomechanical effects and predict COP in young verses presbyopic eyes. 

The FEM was able to demonstrate 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 both accommodation and disaccommodation 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. Comparative FEM simulations to published works will be presented. The utility of the FEM using predictive capabilities is further explored in virtual reality case examples of therapeutic and surgical interventions.

Utilization of a FEM of the accommodation system allows for a deeper understanding of the mechanism of accommodation and the effects of age. We were able to demonstrate the connection between the age-related parameters of the lens, and extralenticular structures which effect the amplitude of accommodation and COP by 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.