Quantitative assessment of corneal biomechanical properties using optical coherence elastography and a modified Rayleigh Lamb-frequency model

Abstract

This study reports the application of a modified Rayleigh-Lamb frequency equation (RLFE) to a noncontact optical coherence elastography (OCE) method for quantitative assessment of the biomechanical properties of a porcine cornea. A focused air-pulse induced an elastic wave in the cornea, which was imaged by a phasestabilized optical coherence tomography (OCT) system. From the displacement data acquired by the OCT system, phase velocities of the mechanical wave were extracted by spectral analysis using a fast Fourier transform. Experiments were conducted on 2% agar phantom samples, and the Young’s moduli were assessed by the Rayleigh-Lamb frequency equation, which was validated using uniaxial mechanical compression testing. The Rayleigh-Lamb frequency equation was then applied to OCE data from a normal porcine cornea, in which the fluid-solid effect was considered. The Young’s modulus of the porcine cornea was measured to be ~60 kPa and the shear viscosity was ~0.33 <i>Pa·s</i>. The combination of OCE and RLFE is a promising noninvasive method for the estimation of the biomechanical properties of the cornea <i>in vivo</i>.