Poster Session: Estimation of crystalline lens mechanical properties from patient accommodation data.

Presbyopia is thought to involve changes in stiffness of the crystalline lens. Quantifying such changes poses challenges due to the nature of the lens' materials. One approach has been to use finite element models and deformation profiles of lenses to estimate elastic moduli. In this work, this approach is extended to accommodation data for individual subjects. 11 subjects aged 20 to 30 were measured in an OCT system to record their accommodative response to a 4.5D stimulus. Lens surfaces were reconstructed from a diameter of 6mm and the periphery of the lens was estimated using eigenlenses method. The resulting profiles were used as input for a finite element model of accommodation. The lens was modelled with two primary components (nucleus and cortex) with elastic moduli for each region set as a variable. A load of 0.05-0.06N was used to approximate the accommodative process. An inverse modeling procedure was used to estimate cortical and nuclear moduli, by minimizing the difference between experimental and simulated surfaces at maximum deformed state. Estimated mean nuclear and cortical moduli values were 1.42 kPa (SD 1.16) and 7.07 kPa (SD 4.81). For all lenses evaluated, nuclear modulus was lower than cortical modulus. Age dependence was found for the average elastic modulus (R2 0.83) and for nuclear (R2 0.5) and cortical (R2 0.45) moduli. Results suggest that this method can be used to quantify stiffness of crystalline lens in subjects.