  Objective: The mechanical properties of corneal tissues play a crucial role
in determining corneal shape and have significant implications in vision care.
This study aimed to address the challenge of obtaining accurate in vivo data
for the human cornea. Methods: We have developed a high-frequency optical
coherence elastography (OCE) technique using shear-like antisymmetric (A0)-mode
Lamb waves at frequencies above 10 kHz. Results: By incorporating an
anisotropic, nonlinear constitutive model and utilizing the acoustoelastic
theory, we gained quantitative insights into the influence of corneal tension
on wave speeds and elastic moduli. Our study revealed significant spatial
variations in the shear modulus of the corneal stroma on healthy subjects for
the first time. The central cornea exhibited a shear modulus of 74 kPa, while
the corneal periphery showed a decrease to 41 kPa. The limbus demonstrated an
increased shear modulus exceeding 100 kPa. We obtained wave displacement
profiles that are consistent with highly anisotropic corneal tissues.
Conclusion: Our approach enabled precise measurement of corneal tissue elastic
moduli in situ with high precision (< 7%) and high spatial resolution (< 1 mm).
Significance: The high-frequency OCE technique holds promise for biomechanical
evaluation in clinical settings, providing valuable information for refractive
surgeries, degenerative disorder diagnoses, and intraocular pressure
assessments.
