Xu Mengchen, Ramirez-Garcia Manuel A, Narang Harshita, Buckley Mark R, Lerner Amy L, Yoon Geunyoung
Department of Mechanical Engineering, University of Rochester, Rochester, New York, United States.
Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States.
Invest Ophthalmol Vis Sci. 2020 Aug 3;61(10):54. doi: 10.1167/iovs.61.10.54.
The spatial distribution of collagen fibril dispersion has a significant impact on both corneal biomechanical and optical behaviors. The goal of this study was to demonstrate a novel method to characterize collagen fibril dispersion using intraocular pressure (IOP)-induced changes in corneal optical aberrations for individualized finite-element (FE) modeling.
The method was tested through both numerical simulations and ex vivo experiments. Inflation tests were simulated in FE models with three assumed patterns of collagen fibril dispersion and experimentally on three rhesus monkey corneas. Geometry, matrix stiffness, and the IOP-induced changes in wavefront aberrations were measured, and the collagen fibril dispersion was characterized. An individualized corneal model with customized collagen fibril dispersion was developed, and the estimated optical aberrations were compared with the measured data.
For the theoretical investigations, three assumed distributions of fibril dispersion were all successfully characterized. The estimated optical aberrations closely matched the measured data, with average root-mean-square (RMS) differences of 0.29, 0.24, and 0.10 µm for the three patterns, respectively. The overall features of the IOP-induced changes in optical aberrations were estimated for two ex vivo monkey corneas, with average RMS differences of 0.57 and 0.43 µm. Characterization of the fibril dispersion in the third cornea might have been affected by corneal hydration, resulting in an increased RMS difference, 0.8 µm.
A more advanced corneal model with individualized distribution of collagen fibril dispersion can be developed and used to improve our ability to understand both biomechanical and optical behaviors of the cornea.
胶原纤维分散的空间分布对角膜的生物力学和光学行为均有显著影响。本研究的目的是展示一种利用眼压（IOP）引起的角膜光学像差变化来表征胶原纤维分散的新方法，用于个体化有限元（FE）建模。
该方法通过数值模拟和离体实验进行测试。在具有三种假定胶原纤维分散模式的有限元模型中模拟膨胀测试，并在三只恒河猴角膜上进行实验。测量几何形状、基质刚度以及IOP引起的波前像差变化，并表征胶原纤维分散情况。开发了具有定制胶原纤维分散的个体化角膜模型，并将估计的光学像差与测量数据进行比较。
对于理论研究，三种假定的纤维分散分布均成功表征。估计的光学像差与测量数据紧密匹配，三种模式的平均均方根（RMS）差异分别为0.29、0.24和0.10μm。估计了两只离体猴角膜IOP引起的光学像差变化的总体特征，平均RMS差异为0.57和0.43μm。第三只角膜中纤维分散的表征可能受到角膜水化的影响，导致RMS差异增加至0.8μm。
可以开发一种具有个体化胶原纤维分散分布的更先进角膜模型，并用于提高我们理解角膜生物力学和光学行为的能力。
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