Regnault Gabriel, Kirby Mitchell A, Wang Ruikang K, Shen Tueng T, O'Donnell Matthew, Pelivanov Ivan
Department of Bioengineering, University of Washington, Seattle, USA.
Department of Ophthalmology, University of Washington, Seattle, USA.
ArXiv. 2023 Jun 26:arXiv:2306.15018v1.
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (A$\mu$T) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from $\sim 100\mu m$ in the periphery to $\sim 150\mu m$ in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
角膜交联（CXL）通常用于预防或治疗圆锥角膜。虽然通过跟踪机械波传播，非接触式动态光学相干弹性成像（OCE）可以监测CXL手术引起的角膜硬度变化，但如果角膜不是全层交联，深度依赖性变化仍不清楚。在这里，光学相干断层扫描（OCT）结构图像上的相位去相关测量与声学微敲击（AμT）OCE相结合，以探索在离体人角膜样本中交联角膜内深度依赖性硬度的可能重建。分析实验性OCT图像以确定CXL进入角膜的穿透深度。在一个具有代表性的离体人角膜样本中，交联深度从周边的约100μm到角膜中心的约150μm不等，并且在交联区域和未处理区域之间呈现出明显的深度转变。该信息用于分析性双层导波传播模型，以量化处理层的硬度。我们还讨论了部分CXL处理的角膜层的弹性模量如何反映整个角膜的有效工程硬度，以正确量化角膜变形。
