Acoustic Micro-Tapping Optical Coherence Elastography to Quantify Corneal Collagen Cross-Linking
Mitchell A. Kirby, Ivan Pelivanov, Gabriel Regnault, John J. Pitre, Ryan T. Wallace, Matthew O’Donnell, Ruikang K. Wang, Tueng T. Shen
Abstract
Purpose: To evaluate changes in the anisotropic elastic properties of ex vivo human cornea treated with ultraviolet cross-linking (CXL) using noncontact acoustic micro-tapping optical coherence elastography (AμT-OCE). Design: Acoustic micro-tapping OCE was performed on normal and CXL human donor cornea in an ex vivo laboratory study. Subjects: Normal human donor cornea (n = 22) divided into 4 subgroups. All samples were stored in optisol. Methods: , shear modulus) of normal and ultraviolet CXL-treated human corneas were quantified using noncontact AμT-OCE. A nearly incompressible transverse isotropic model was used to reconstruct moduli from AμT-OCE data. Independently, cornea elastic moduli were also measured with destructive mechanical tests (tensile extensometry and shear rheometry). Main Outcome Measures: , shear moduli) can be evaluated in both normal and CXL treated tissues, as well as monitored during the CXL procedure using noncontact AμT-OCE. Results: increased from 188 kPa to 673 kPa. Mechanical tests in a separate subgroup support CXL-induced cornea moduli changes and generally agree with noncontact AμT-OCE measurements. Conclusions: The human cornea is a highly anisotropic material where in-plane mechanical properties are very different from those out-of-plane. Noncontact AμT-OCE can measure changes in the anisotropic elastic properties in human cornea as a result of ultraviolet CXL.