In vivo Optical Coherence Elastography Reveals Spatial Variation and Anisotropy of Corneal Stiffness

TL;DR

This study introduces a high-frequency optical coherence elastography technique to measure in vivo corneal stiffness, revealing spatial variations and anisotropy in healthy human corneas with high precision and resolution.

Contribution

The paper presents a novel high-frequency OCE method using antisymmetric Lamb waves to quantify corneal elastic properties in vivo, highlighting spatial variation and anisotropy.

Findings

Central cornea shear modulus of 74 kPa

Peripheral cornea shear modulus decreases to 41 kPa

Limbus shear modulus exceeds 100 kPa

Abstract

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.