Acoustic Micro-Tapping Optical Coherence Elastography to Quantify Corneal Collagen Cross-Linking

• Published in: Ophthalmology science (Online) Vol. 3; no. 2; p. 100257
• Main Authors: Kirby, Mitchell A., Pelivanov, Ivan, Regnault, Gabriel, Pitre, John J., Wallace, Ryan T., O’Donnell, Matthew, Wang, Ruikang K., Shen, Tueng T.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.06.2023; Elsevier
• Subjects: Cornea; Cross-linking; Elastic Anisotropy; NITI model; Optical Coherence Elastography; UV; Cornea; Elastic Anisotropy; BSS; NITI model; Optical Coherence Elastography; IOP; OCE; NITI; RF; Cross-linking; CXL; AμT
• ISSN: 2666-9145; 2666-9145
• DOI: 10.1016/j.xops.2022.100257

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). Acoustic micro-tapping OCE was performed on normal and CXL human donor cornea in an ex vivo laboratory study. Normal human donor cornea (n = 22) divided into 4 subgroups. All samples were stored in optisol. Elastic properties (in-plane Young’s, E, and out-of-plane, G, 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). Corneal elastic moduli (in-plane Young’s modulus, E, in-plane, μ, and out-of-plane, G, shear moduli) can be evaluated in both normal and CXL treated tissues, as well as monitored during the CXL procedure using noncontact AμT-OCE. Cross-linking induced a significant increase in both in-plane and out-of-plane elastic moduli in human cornea. The statistical mean in the paired study (presurgery and postsurgery, n = 7) of the in-plane Young’s modulus, E=3μ, increased from 19 MPa to 43 MPa, while the out-of-plane shear modulus, G, 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. 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. Proprietary or commercial disclosure may be found after the references.