谱域光学相干层析成像的深度拓展及其在眼调节研究中的应用

发布时间：2018-06-02 22:31

本文选题：光学相干层析成像 + 成像深度　；参考：《上海交通大学》2015年博士论文

【摘要】：精准、快速、有效的眼组织成像和参数测量对眼科基础研究和临床诊疗具有十分重要的应用价值。在临床眼科成像技术中,光学相干层析成像技术(Optical Coherence Tomography,OCT)以其无接触、非侵入、高分辨率、高速、实时等优点,在眼科疾病检测和临床研究中呈现出巨大的潜力。但是,由于成像深度的限制,常用OCT系统无法实现对全眼前节乃至全眼结构的同时成像,限制了其在眼科领域的应用范围。因此,本文的研究目的在于拓展谱域OCT(Spectral-domain OCT,SD-OCT)系统的探测深度,使之能够准确完整地反映全眼组织层析结构特征,以提供更加丰富有价值的全眼参数信息用于眼科基础研究和临床检查。针对以上研究目的,本研究利用双通道双焦点技术与消共轭技术相结合的方法,研制并优化大成像范围的SD-OCT系统,实现了高分辨率全眼组织同时成像,并利用以上技术对调节所引起的眼内组织形态变化进行了全面深入的研究。本论文的主要研究内容和结果如下:首先,研制双通道双焦点SD-OCT系统,成功实现了对人眼全眼前节组织的同时成像及参数测量并保证了较高的横向分辨率。将该系统用于观察放松和不同调节状态下的眼前节参数变化,实验结果支持了经典眼调节理论,同时也证实了双通道双焦点SD-OCT系统用于眼前节参数测量和眼调节功能研究中的可行性。其次,为了进一步提高系统的成像深度,在原有双通道双焦点sd-oct系统的基础上,结合消共轭技术,成功实现了全眼前节和视网膜的同时成像,并基于合成的全眼图像测得了相应的眼参数。实验结果证明该系统对人眼轴向参数的测量具有很好的重复性。另外,将该系统与临床常用的iolmaster生物测量仪进行对比,发现两者对前房深度和眼轴长的测量结果具有高度的相关性和一致性。因此,消共轭型双通道双焦点sd-oct系统可作为一种准确可靠的生物成像测量技术为临床眼科诊断和研究提供更详细丰富的图像信息。再次,由于调节引起的视网膜牵拉或变形可能与视觉感知变化有关,高分辨率的影像测量学技术可为研究调节引起的视网膜厚度变化以及牵拉现象提供一种更直接准确的定量分析。本研究利用改进的双通道双焦点sd-oct系统对人眼最大调节前后的角膜和视网膜同时进行三维成像,并计算了视网膜厚度、视网膜体积和眼轴长。实验结果表明,在最大调节状态下,中央凹周围4-mm2黄斑区域的视网膜显著变薄,且该变化与象限无关。这是首次利用视网膜厚度变化的影像测量学证据证明了人眼调节时视网膜可能存在的牵拉或变形现象。最后,为进一步解决视网膜成像范围和系统成像信噪比受限等问题,研制了一套中心波长在1050nm和840nm的双波段双焦点sd-oct系统,实现了大范围、高探测灵敏度的全眼组织同时成像。利用双波段探测光束和样品臂的特殊光学设计,不但解决了原系统信号衰减的问题,而且实现了双扫描双焦点结构,从而最优化两个成像通道(特别是对视网膜成像)的横向分辨率、焦深和扫描范围。将该系统用于观察和测量+6d调节前后的全眼参数变化,实验结果与经典眼调节假说基本一致,同时该研究还发现了调节时眼轴长显著增加。调节引起的眼轴伸长可能与近距离工作引起的暂时性近视的发生相关。因此,该成像系统不仅能用于眼科疾病的检测,同时还能为眼调节、屈光不正等眼视光学研究提供强有力的技术支持。本论文重点解决了SD-OCT系统成像深度拓展和同时大范围成像的技术难题,实现了全眼组织的高分辨率同时成像和眼参数的高精度测量。同时,利用所研制的系统,精确测量了眼调节引起的全眼组织形态变化,从中发现了调节引起的眼轴长增加和视网膜牵拉的直接证据。本论文的研究成果不仅为眼科疾病的检查诊断和基础研究提供了一种强大的成像测量工具,也为眼调节功能的深入研究提供了有利的理论依据和实验参考。
[Abstract]:Accurate, rapid and effective eye tissue imaging and parameter measurement are of great value for the basic ophthalmology and clinical diagnosis and treatment. In the clinical ophthalmic imaging technology, Optical Coherence Tomography (OCT) has the advantages of non contact, non invasion, high resolution, high speed, real-time and so on, in the ophthalmological examination. However, because of the limitation of imaging depth, the common OCT system can not achieve simultaneous imaging of the whole eye and the whole eye structure, which limits its application in the field of Ophthalmology. Therefore, the purpose of this study is to expand the depth of the detection depth of the spectral domain OCT (Spectral-domain OCT, SD-OCT) system. It can accurately and completely reflect the structural characteristics of the whole eye tissue, so as to provide more valuable information of all eye parameters for basic ophthalmology and clinical examination. For the purpose of the above research, this study develops and optimizes the SD-OCT system of large imaging range by the combination of dual channel dual focus technology and elimination of conjugation. The main research contents and results of this paper are as follows: first, a dual channel dual focus SD-OCT system is developed, which successfully realizes simultaneous imaging of the eyes of the eye. The parameters are measured and the high lateral resolution is guaranteed. The system is used to observe the changes in the parameters of the anterior segment under the condition of relaxation and adjustment. The experimental results support the classical eye adjustment theory. At the same time, it also proves the feasibility of the dual channel dual focus SD-OCT system in the study of the parameters measurement and eye regulation. Secondly, In order to further improve the imaging depth of the system, on the basis of the original dual channel dual focus SD-OCT system, combined with the elimination of conjugation technique, the simultaneous imaging of the whole eyes and the retina is successfully realized, and the corresponding eye parameters are measured on the basis of the synthetic full eye image. The experimental results show that the system has a good weight for the measurement of the axial parameters of the human eye. In addition, comparing the system with the commonly used clinical IOLMaster biometric instrument, it is found that both of them have high correlation and consistency for the measurement of anterior chamber depth and axial length. Therefore, the conjugate dual channel dual focus SD-OCT system can be used as an accurate and reliable bioimaging technique for clinical ophthalmology diagnosis and The study provides more detailed image information. Again, the retina traction or deformation caused by adjustment may be associated with visual perception changes. High resolution imaging techniques provide a more direct and accurate quantitative analysis for the study of changes in retinal thickness and traction caused by adjustment. The double channel dual focus SD-OCT system performs three dimensional imaging of the cornea and the retina before and after the maximum adjustment of the human eye, and calculates the retinal thickness, retina volume and eye axis. The experimental results show that the retina in the 4-mm2 macular region around the central concave is thinner and the change is not related to the quadrant in the maximum regulation state. In order to further solve the problems of retina imaging range and the limitation of the signal to noise ratio of the system, a set of dual focus SD-OCT system with central wavelength of 1050nm and 840nm is developed. Large range, high detection sensitivity full eye imaging. Using the special optical design of dual band detection beam and sample arm, it not only solves the problem of the signal attenuation of the original system, but also realizes the double scanning dual focus structure, thus optimizing the transverse resolution, focal depth and scanning of the two imaging channels, especially to the retina imaging. The range. The system is used to observe and measure the changes of all eye parameters before and after the +6d regulation. The experimental results are basically consistent with the classical eye regulation hypothesis. Meanwhile, the study also found that the axial length of the eye is significantly increased during the adjustment. The axis elongation caused by the adjustment may be related to the occurrence of temporary myopia caused by the close distance work. Therefore, the imaging system It can not only be used for the detection of ophthalmological diseases, but also provide strong technical support for eye optic research, such as eye adjustment and refractive error. This paper focuses on the technical problems of the depth expansion of the SD-OCT imaging system and the large range imaging at the same time. The high resolution simultaneous imaging of the whole eye and the high precision measurement of the eye parameters are realized. At the same time, the whole eye tissue morphologic changes caused by eye regulation were measured accurately by using the developed system. The direct evidence for the increase of axial length and retina traction caused by adjustment was found. The results of this paper not only provide a powerful imaging tool for the examination and diagnosis of ophthalmological diseases, but also for the eye. The in-depth study of joint function provides favorable theoretical basis and experimental reference.
【学位授予单位】：上海交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R770.4

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