角膜地形图系统复原算法研究及其应用

发布时间：2018-02-02 17:10

本文关键词： 角膜地形图角膜复原 Placido盘屈光度特征点提取　出处：《南京航空航天大学》2010年硕士论文　论文类型：学位论文

【摘要】：随着角膜外科手术的发展,角膜地形图系统已经成为眼科诊疗中必不可少的设备。Placido圆盘检查角膜地形是应用最为广泛的检查手段,它具有精度高、成本低等特点,并且结构简单,对噪声敏感度低,相比其他检查方法更适合于临床应用。本文致力于Placido盘检查方法的复原算法研究与应用,在传统方法的基础上,提出一种基于精确角膜顶点定位的复原算法,并在本文算法的基础上开发角膜地形图软件系统。论文主要的研究工作如下: 1.研究了角膜的结构和生理特性,介绍了角膜地形图的历史和发展现状。 2.对角膜地形图系统的关键技术展开研究,介绍了其系统原理以及硬件构成。阐述了角膜地形图图像采集过程中的自动对中和自动对焦的方法;研究了图像分析处理的方法,包括图像预处理,中心定位以及特征点提取的方法。 3.对传统的角膜复原方法进行深入的分析探讨,并提出一种基于精确定位角膜顶点的复原算法,通过引入单球面镜反射公式求解第一反射点和角膜顶点的位置关系,以此精确定位角膜顶点,在此基础上计算了反射点的位置以及屈光度。通过建立屈光度数据场网格以及线性颜色编码表,最终获得屈光度伪彩图。 4.在本文算法的基础上,给出角膜局部数量化参数以及全局参数的计算方法。局部参数包括屈光度信息和高度信息,全局参数包括模拟角膜镜读数、表面不规则指数和表面规则指数。探讨各种局部参数的特点以及适用场合,并且分析了全局参数的意义。 5.选用多个标准球对本文算法的精度和稳定性能进行验证,结果表明本文算法精度优于传统的方法,并且适用于较大的屈光度范围,满足临床要求。
[Abstract]:With the development of corneal surgery, corneal topographic system has become an indispensable equipment in ophthalmology diagnosis and treatment. Placido disc examination of corneal topography is the most widely used means of examination. It has the characteristics of high precision, low cost, simple structure and low sensitivity to noise. Compared with other methods, this paper is more suitable for clinical application. This paper focuses on the research and application of restoration algorithm of Placido disk inspection method, based on the traditional methods. A restoration algorithm based on accurate corneal vertex location is proposed, and a corneal topographic software system is developed on the basis of this algorithm. The main research work of this paper is as follows: 1. The structure and physiological characteristics of cornea were studied, and the history and development of corneal topography were introduced. 2. The key technology of corneal topographic map system is studied, the system principle and hardware structure are introduced, and the method of automatic alignment and auto-focusing in the process of corneal topographic image acquisition is described. The methods of image analysis and processing, including image preprocessing, center location and feature point extraction, are studied. 3. The traditional corneal restoration method is deeply analyzed and discussed, and an algorithm based on accurate location of corneal vertex is proposed. By introducing the single spherical mirror reflection formula to solve the position relationship between the first reflection point and the corneal vertex, the corneal vertex can be accurately located. On this basis, the position and diopter of the reflection point are calculated, and the pseudo-color diopter image is obtained by establishing the grid of refraction data field and the linear color coding table. 4. Based on this algorithm, the calculation method of corneal local quantization parameters and global parameters is given. The local parameters include refraction information and height information, and the global parameters include simulated corneal reading. The surface irregularity index and surface rule index are discussed. The characteristics and application of various local parameters are discussed, and the significance of global parameters is analyzed. 5. The accuracy and stability of the algorithm are verified by using several standard spheres. The results show that the accuracy of the proposed algorithm is superior to that of the traditional method, and it is suitable for a wide range of diopters and meets the clinical requirements.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2010
【分类号】：TP391.41;R779.6

【参考文献】