基于裂隙扫描图像的角膜表面三维重建

A New Approach to the Surface Reconstruction of Corneal Based on Slit-lamp Imaging

角膜是人眼的重要组成部分,眼外科中对角膜表面检查一般采用基于Placido盘的角膜地形图法和裂隙扫描角膜地形图法,但这两种方法的结果都未能获得直观的角膜表面三维模型。本研究设计的一种基于裂隙扫描图像的角膜表面三维重建算法,实现了对角膜前后表面的重建,并能快速地计算出角膜前后表面的几何参数以及转换成传统的等高线图和地形图,方便了医生的诊断。该算法首先采集角膜的裂隙扫描图像序列,然后在图像集中提取出每层角膜的轮廓,进而采用轮廓线重构算法得到角膜表面模型。在对裂隙图像提取闭合轮廓线时,根据角膜区域的颜色差异,采用了色彩分割的算法;针对角膜轮廓线是凹的特点,对轮廓线重构算法做了改进,以便能构造出正确的角膜表面三角形网格。

Cornea is an important part of eyeball. There are two clinical methods that are commonly used in measuring corneal shape. One is Placido-based corneal topography, and the other is Orbscan corneal topography. By using both technologies, 3D corneal surface model can not be obtained. In this paper, a new approach to the surface reconstruction of corneal based on slit-lamp imaging was proposed, which realize visualization for 3D structure of corneal anterior and posterior surface and gain the geometric parameters of its shape fast. At the meantime the results can be transferred the hypsographic map and the topography map to diagnose easily. The algorithm firstly acquires an image series using slit-lamp, secondly extracts the contour of the corneal, at last the corneal surface model is produced using algorithm of contour reconstruction. In abstracting the contour, we adopt color segmentation method according to the difference of the corneal zone. Against the concave characteristics of corneal contour, we improve the algorithm of contour reconstruction to increase the robust of algorithm and obtain the triangle mesh of corneal surface.