Localized Elastography Map of Human Cornea Through Surface Vibrations

Elastography techniques are being developed to diagnose and monitor the progression and treatment of diseases that correlate with changes in soft tissue stiffness. The objective of this paper is to outline the application of vibrations to the human cornea in order to reconstruct a stiffness map. Having a localized stiffness map is useful for early diagnosis of cornea related diseases such as glaucoma and keratoconus. Experimental data was collected by directly vibrating the excised cornea axisymetrically along the edge and measuring wave propagation inward with the use of laser vibrometry. Different methods have been implemented to increase the reflectivity of the cornea for laser vibrometry. To corroborate the data, as well as to test feasibility, experiments have been done on phantoms constructed from silicone-based polymers. To reconstruct the data into a stiffness map, an appropriate analytical model has to be derived. This paper outlines the derivation of the analytical model for the cornea starting with simple circular plates and moving towards the curved geometry of the cornea. To verify the analytical model, finite element simulations were used to replicate the results. These results have also been checked against experimental data to help determine any external variables that affect results. Overall, the feasibility and application of a process has been determined. Future goals include increasing in-vivo application to make the process safe and cost-effective.