A whole eye finite element analysis of accommodation

The young human eye has the ability to change focus from far to near distance by changing the shape of the lens in a process called accommodation. Contraction of the ciliary muscle drives accommodation. Hypothetically it also plays a mechanical role in the etiology of glaucoma and presbyopia. Biomechanical assessment of the associated tissues has been done primarily with tissue samples in isolation after dissection, or through optometric measurements. The ciliary muscle has been inaccessible without dissection, except with various imaging modalities, including UBM OCT and MRI. However, it has not been well characterized in terms of its contraction kinetics. To address this gap in knowledge a biomechanical finite element analysis (FEA) model was built of the entire globe of the eye that includes the tissue components in the loading pathway of accommodative forces, and with an active ciliary muscle. This time-based model, consisting of discrete 3D geometric regions for each tissue, was populated with tissue material models from literature, and calibrated based on reported measurements of tissue movement from the clinical literature. It is hoped that the knowledge and modeling tools from this work will provide a platform for future study of pathologies associated with accommodation.