Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland.
Department of Mechanics, Materials and Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland.
PLoS One. 2021 Mar 26;16(3):e0249213. doi: 10.1371/journal.pone.0249213. eCollection 2021.
The aim of this study was to evaluate the influence of increase in intraocular pressure (IOP) and cooccurring changes in ocular biometry parameters on the corneal optical coherence tomography (OCT) speckle distribution in ex-vivo experiments on porcine intact eyes. Twenty-three eyeballs were used in the inflation test where IOP in the anterior chamber was precisely set from 10 mmHg to 40 mmHg in steps of 5 mmHg and where eye biometry was utilized (IOL Master 700). To assess the influence of the duration of the experiment on the OCT speckle statistics, the second experiment was performed with 10 eyeballs at the constant IOP of 15 mmHg. Based on the OCT scans of central cornea (Copernicus REVO), spatial maps of the scale parameter (a) and the shape parameter (v) of the gamma distribution speckle model were estimated. The means of both parameters for each spatial map were computed within the 2 mm of the central stroma. Both distributional parameters statistically significantly varied with IOP and time (one way repeated measures ANOVA, all p-values < 0.001). The a parameter revealed a faster statistically significant increase in IOP up to 25 mmHg, regardless of time. Central corneal thickness (CCT), the anterior chamber depth, and the mean equivalent spherical power varied significantly with IOP, whereas CCT and axial length changed statistically significantly with time. Statistically significant correlation was found between CCT and the a parameter, after removing IOP as a confounding factor (r = -0.576, p < 0.001). The parameters of the gamma distribution can be used not only for identifying IOP induced changes in the optical scattering within the corneal stroma, but also in corneal geometry. The approach of corneal speckle analysis could be potentially utilized for an indirect and noninvasive assessment of some properties of corneal stroma.
本研究旨在评估眼内压（IOP）升高以及眼生物测量参数同时发生的变化对离体猪眼实验中角膜光学相干断层扫描（OCT）散斑分布的影响。在膨胀试验中使用了 23 只眼球，在前房中精确设定 IOP 从 10mmHg 逐步增加到 40mmHg，步长为 5mmHg，并利用 IOL Master 700 进行眼生物测量。为了评估实验持续时间对 OCT 散斑统计的影响，在恒定的 IOP 为 15mmHg 的情况下对 10 只眼球进行了第二次实验。基于中央角膜（Copernicus REVO）的 OCT 扫描，估计了伽马分布散斑模型的尺度参数（a）和形状参数（v）的空间图。在中央基质 2mm 范围内计算了每个空间图的两个参数的平均值。两个分布参数均与 IOP 和时间呈统计学显著相关（单向重复测量方差分析，所有 p 值均<0.001）。无论时间如何，a 参数均显示出与 IOP 快速且统计学显著的增加，直到 25mmHg。中央角膜厚度（CCT）、前房深度和平均等效球镜度数与 IOP 显著相关，而 CCT 和眼轴长度与时间呈统计学显著相关。在去除 IOP 作为混杂因素后，发现 CCT 与 a 参数之间存在统计学显著相关性（r = -0.576，p <0.001）。伽马分布的参数不仅可用于识别 IOP 诱导的角膜基质内光学散射变化，还可用于角膜几何形状。角膜散斑分析方法可用于间接和非侵入性地评估角膜基质的某些特性。
