【作者】 曹正林；

【导师】 廖文和；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2007， 博士

【摘要】 近年来,随着光学测量手段的发展和提高,人眼波前像差的测量与矫正技术也得到迅速发展。当前,波前像差引导的角膜个体化切削技术已成为眼科领域的研究热点。论文系统研究了眼波前像差的测量,波前像差的矫正手术以及准分子激光屈光不正矫正手术中的关键技术,论文的主要内容如下:1.系统地叙述了人眼的视光学原理,眼波前像差的概念与分类,眼波前像差的Taylor级数和Zernike多项式表示法。2.系统地研究了主观式波前像差仪中的图像处理与自动跟踪技术。对测量过程中捕捉到的瞳孔图像采用Ostu方法进行分割,使瞳孔图像与背景图像分离;然后利用探测法跟踪瞳孔图像的边界,采用多次跟踪的方法实现对瞳孔图像边界的精确跟踪;对跟踪到的瞳孔边界点,采用了等距离选点,大距离组点的方法,利用点Hough变换计算出瞳孔的中心坐标和半径;采用自动跟踪技术对测量过程中人眼的转动进行自动跟踪补偿。3.深入研究了基于Zernike多项式的波前重构技术。提出了基于改进的Gram-Schmidt正交化的拟合算法以及基于Householder变换的拟合算法来求解波前拟合中的未知模式系数。并对改进的Gram-Schmidt正交化法、Householder变换法,以及传统的构造法方程组法的拟合精度进行了比较。4.研究了准分子激光矫正屈光不正的关键技术。基于非球面因子的角膜曲面方程,提出了非球面因子的屈光不正矫正模型以及过渡区角膜切削量计算模型,并对模型进行了计算仿真。该模型适用于矫正单纯近视和单纯远视,可有效降低术后眼球差的增加,减少术后视力的回退。5.完善和发展了项目组研究的波前像差引导的个体化切削手术中的关键技术。建立了波前像差与角膜切削量之间的关系,并对波前像差矫正模型进行了计算仿真;深入研究了准分子激光眼科治疗机中的小光斑飞点扫描算法,对飞点扫描过程进行了计算仿真。6.研究了主观式波前像差仪的硬件和软件系统,以及矫正模型在准分子激光眼科治疗机中的实现情况。同有关单位合作,研制出世界上第一台主观式波前像差仪。该仪器能精确测量出人眼的低价和高级像差,与准分子激光眼科治疗机一起构成了准分子激光人眼像差矫正系统,目前该系统已进入产业化生产,应用前景非常广阔。更多还原

【Abstract】 In recent years, with the development and improvement of the optical measurements, the techniques for wavefront aberration measurement and correction have been developing rapidly. At present, wavefront aberration guided customized corneal ablation surgery has become the researching focus in ophthalmology. The paper has studied the key techniques for the measurement of wavefront aberration of the human eye’s, wavefront aberration correction surgery and excimer laser refractive surgery. Main research achievements of the paper are as following:1. The principle of human eye’s visual optics was systematically described. The concept and classes of the human eye’s wavefront aberration were presented. The mathematical expressions of the wavefront aberration based on Taylor series and Zernike polynomials were also presented.2. The key techiniques of image processing and auto-tracing in subjective wavefront aberrometer were systematically researched. Using Ostu method to segment the captured pupil’s image, then applying Multiple detecting method for tacing the boundary of pupil’s image. The coordinates of the pupil’s center and the radii was calculated using Point Hough Transform under the principle of equal distance selecting points and large distance combining points. In order to compensate the movement of the eye in the process of measuring eye’s wavefront aberration, the auto-tracing technique was used.3. The technique for wavefront reconstruction based on Zernike polynomials was researched. The fitting algorithm based on developed Gram-Schmidt orthogonalization and Householder transformation were put forward. The unknown Zernike coefficients could be wored out using these two fitting algorithm. The fitting precision of these two algorithms was also compared with traditional constructing normal equation group method.4. The key techniques for excimer laser refractive surgery were presented. The refractive correction model based on aspherical factor was put forward. The transition zone model was also bring forward. Ablation models based on aspherical factor were simulated on computer. The model could be used to correct the simple myopia and simple hyperopia. Using this model can effectively reduce the spherical aberration in postoperative eyes and decrease the regression of visual sights.5. The key techniques in wavefront-guided laser customized ablation surgery were developed. The ablation profile for the correction of wavefront aberration is presented and simulated on computer. The process of scanning-spot excimer laser was studied and simulated on computer.6. The hardware system and software system of subjective wavefront aberrometer was presented. The ablation model was used in ophthalmic excimer laser system (AOV-FB system). With the cooperaton of Suzhou 66 Vision Tech Co.Ltd, the subjective wavefront aberrometer has been developed. It can accurately measure the low-order and high order aberrations in humen eyes. Combined with AOV-FB, it makes the Ophthalmic excimer laser system (AOV-FB system). At present, the system has entered the industrialization period. It will be widely used in the future.更多还原