Ortiz Sergio, Siedlecki Damian, Grulkowski Ireneusz, Remon Laura, Pascual Daniel, Wojtkowski Maciej, Marcos Susana
Instituto de Optica Daza de Valdés, Consejo Superior de Investigaciones Científicas, 28006 Madrid, Spain.
Opt Express. 2010 Feb 1;18(3):2782-96. doi: 10.1364/OE.18.002782.
A method for three-dimensional 3-D optical distortion (refraction) correction on anterior segment Optical Coherence Tomography (OCT) images has been developed. The method consists of 3-D ray tracing through the different surfaces, following denoising, segmentation of the surfaces, Delaunay representation of the surfaces, and application of fan distortion correction. The correction has been applied theoretically to realistic computer eye models, and experimentally to OCT images of: an artificial eye with a Polymethyl Methacrylate (PMMA) cornea and an intraocular lens (IOL), an enucleated porcine eye, and a human eye in vivo obtained from two OCT laboratory set-ups (time domain and spectral). Data are analyzed in terms of surface radii of curvature and asphericity. Comparisons are established between the reference values for the surfaces (nominal values in the computer model; non-contact profilometric measurements for the artificial eye; Scheimpflug imaging for the real eyes in vivo and vitro). The results from the OCT data were analyzed following the conventional approach of dividing the optical path by the refractive index, after application of 2-D optical correction, and 3-D optical correction (in all cases after fan distortion correction). The application of 3-D optical distortion correction increased significantly both the accuracy of the radius of curvature estimates and particularly asphericity of the surfaces, with respect to conventional methods of OCT image analysis. We found that the discrepancies of the radii of curvature estimates from 3-D optical distortion corrected OCT images are less than 1% with respect to nominal values. Optical distortion correction in 3-D is critical for quantitative analysis of OCT anterior segment imaging, and allows accurate topography of the internal surfaces of the eye.
已经开发出一种用于眼前节光学相干断层扫描（OCT）图像的三维（3-D）光学畸变（折射）校正方法。该方法包括通过不同表面进行三维光线追踪，随后进行去噪、表面分割、表面的德劳内三角剖分以及扇形畸变校正的应用。该校正已在理论上应用于逼真的计算机眼睛模型，并在实验上应用于以下OCT图像：带有聚甲基丙烯酸甲酯（PMMA）角膜和人工晶状体（IOL）的假眼、摘除的猪眼以及从两个OCT实验室设置（时域和光谱）获得的人眼活体图像。根据表面曲率半径和非球面度对数据进行分析。在表面的参考值之间进行比较（计算机模型中的标称值；假眼的非接触轮廓测量；体内和体外真实眼睛的Scheimpflug成像）。在应用二维光学校正和三维光学校正（在所有情况下均在扇形畸变校正之后）之后，按照将光路除以折射率的传统方法对OCT数据的结果进行分析。相对于传统的OCT图像分析方法，三维光学畸变校正的应用显著提高了曲率半径估计的准确性，特别是表面非球面度的准确性。我们发现，经过三维光学畸变校正的OCT图像的曲率半径估计值与标称值的差异小于1%。三维光学畸变校正对于OCT眼前节成像的定量分析至关重要，并能够实现眼睛内表面的精确地形图绘制。
