波前视觉矫正和视神经特性的研究

发布时间：2018-11-06 08:22

【摘要】：由于人眼屈光系统的复杂性，除了存在离焦和像散这样的低阶像差外，还存在各种非规则的高阶像差，它们也是限制视力的重要因素。波前技术的发展，使得验光不再局限于主观验光的离焦和像散，还可以获得包括球差、彗差等高阶像差在内的信息，波前技术使个性化的视觉矫正成为可能。此外，视觉系统包括眼球的光学系统和视网膜之后的神经系统两部分，分段评价整个视觉系统的成像质量，是视觉矫正治疗的前提和目的。神经对比敏感度函数的获取能够为许多眼科疾病的早期发现与及时治疗提供依据。 本文以最优化地矫正人眼像差为主要研究方向，应用波前像差技术，基于个性化的眼光学结构，对以框架眼镜和角膜接触镜为视觉矫正手段的设计方法，以及视功能的评价方面进行了如下研究： 设计了球-柱型波前眼镜。通过综合考虑人眼的2~6阶波前像差，在光学设计软件ZEMAX中建立起个体眼光学结构，在此基础上设计了波前球-柱型眼镜的结构，并给出矫正方案，经过模拟已有文献方法并与之对比，证明本文方法的屈光度结果可信。这种用眼模型设计镜片的方法，更适宜分析镜-眼系统在不同视场角和眼球有旋转时的成像质量。通过对随机选取的50只人眼进行建模分析，发现其中36只眼用这种球-柱镜进行矫正即能达到良好的视觉效果；14只眼仅球-柱矫正后成像改善不明显，尚需要其它面型的进一步矫正。 通过改进Liou的标准眼模型，运用测量的人眼波前像差数据，将离焦引入至晶状体和玻璃体，散光和高阶像差引入至角膜，建立了符合人眼调节特性的个体眼模型。针对于球-柱镜矫正无效的高阶像差较大的个体眼进行屈光矫正设计，利用光学设计中多重结构的设定对应眼球的旋转，每一结构下视场角的设定对应特定的视场要求，从而将人眼的视物特征纳入至镜片的设计中。针对于不同像差特征的人眼，分别将镜片设计为非球面-环曲面型，以及自由曲面-环曲面型。矫正结果表明，对于像散较大、球差较大的眼睛，非球面镜片矫正有效，在大视场的改善尤为明显；对于高阶像差较高，尤其是彗差、三叶草类像差较高的被试眼，自由曲面型眼镜对其矫正最为有效，不仅体现在大视场成像质量的明显提升，甚至对于中心0°视场成像的改善也有成效。这种基于人眼视物特征、运用特殊面型设计镜片的方法，对于某些像散和高阶像差大的人眼的视觉矫正有特殊意义。 提出了一种根据眼视光的客观测量数据获得角膜接触镜面型结构的方法。根据实际测量的角膜地形图数据，运用MATLAB软件编程对角膜前表面进行最佳球面或环曲面拟合，从而设计了角膜接触镜的后表面光学区的面型结构。结合实际测量的人眼波前像差数据，根据衍射的角谱理论，计算波前由出瞳平面传播到角膜前表面、经由泪液透镜及在角膜接触镜介质内的传播，得到角膜接触镜前表面的等效波前像差，进而运用最小二乘法拟合得到矫正该波前像差的角膜接触镜前表面光学区的最优的环曲面面型。由已设计完成的角膜接触镜的前后表面光学区的面型结构，，计算和拟合得到该角膜接触镜的最优球、柱度和散光轴位角。经过与人眼波前、泪液镜的屈光度进行比较，证明本方法结果的可信。与传统配镜的0.125D精度相比，本章拟合得到的屈光度精度仅为0.04D。 为了得到人眼在时间频率下的神经对比敏感度函数，对全眼时间频率下的对比敏感度函数和人眼波前像差分别进行测量。通过建立被试眼的个体眼模型得到眼屈光系统的调制传递函数，再根据对比敏感度函数和调制传递函数间的关联，通过数值计算得到时间频率下的神经对比敏感度函数曲线。测试结果表明：随着时间频率的增高，神经对比敏感度函数曲线整体大幅度降低，并且表现出由类似“带通”至“低通”再过渡至近乎“单调下降”的特点。表征高、低两种时间频率下神经对比敏感度函数变化特征的衰减因子，随空间频率的增加变化平缓，反映了视觉神经系统对于不同运动速度物体的响应特点。
[Abstract]:Due to the complexity of the human eye refractive system, in addition to the low-order aberrations such as defocus and astigmatism, there are various non-regular high-order aberrations, which are also important factors for limiting the vision. The development of the pre-wave technique makes the optometry not limited to the defocus and astigmatism of the subjective optometry, and can also obtain the information including the high-order aberrations including the spherical aberration and the aberration, and the pre-wave technique makes the personalized visual correction possible. In addition, the vision system includes two parts of the optical system of the eye and the nervous system after the retina, and the imaging quality of the whole vision system is evaluated in sections, and the premise and the purpose of the visual correction treatment are the visual system. The acquisition of the nerve-contrast sensitivity function can provide the basis for the early detection and timely treatment of many ophthalmic diseases. In this paper, in order to correct the human eye aberration as the main research direction and to apply the wavefront aberration technique, the design method based on the frame glasses and the contact lens of the cornea as the visual correction means and the evaluation of the visual function are as follows. Study: The ball-column is designed In the optical design software ZEMAX, the structure of the pre-wave ball-column type glasses is designed, and the correction scheme is given, and the existing literature method is simulated. In contrast, the refractive index of the method is proved. The method of designing the lens with the eye model is more suitable for the analysis of the rotation of the lens-eye system at different angles of view and the eyeball By modeling and analyzing the randomly selected 50 human eyes, 36 eyes were found to be corrected with such a ball-column lens to achieve a good visual effect; 14 eyes only-post-correction imaging improvement was not obvious, and other surface-type was still needed. Further, by improving the standard eye model of Liou, using the measured wavefront aberration data of the human eye, introducing the defocus into the lens and the vitreous, the astigmatism and the high-order aberration are introduced into the cornea, and the human eye regulation is established. The invention relates to an individual eye model with characteristics, aiming at the refraction correction design of an individual eye with a large high-order aberration which is not effective in the correction of a ball-column lens, a specific field of view is required to characterize the visual object of the human eye, in the design of the lens, aiming at the human eyes with different aberration characteristics, the lens is designed as an aspheric-ring surface type, and the lens The results show that, for the eyes with larger astigmatism and larger spherical aberration, the correction of the aspherical lens is effective, and the improvement of the large field of view is especially obvious; for the high-order aberrations, especially the eye-eye and the free-curved-type glasses with higher higher-order aberrations, especially the low-order aberration and the clover-like aberration The correction is most effective not only in the significant improvement of the imaging quality of the large field of view, but also for the center 0 掳 field of view. The improvement of the image is also effective, which is based on the characteristics of the human eye, the method of using the special-surface-type design lens, and the vision of the human eye with large astigmatism and high-order aberrations. In this paper, an objective measurement data acquisition angle based on the visual light of the eye is proposed. according to the actual measured corneal topography data, the optimal spherical or ring-surface fitting on the anterior surface of the cornea is obtained by using the MATLAB software programming, so that the contact lens of the cornea is designed, The surface-type structure of the posterior surface optical zone. According to the measured wavefront aberration data of the human eye, according to the diffraction angle spectrum theory, the exit pupil plane is propagated to the anterior surface of the cornea before the wave is calculated, and the contact of the cornea is obtained through the propagation of the tear lens and in the contact lens of the cornea. The equivalent wave front aberration of the front surface of the mirror is obtained by using the least square method to obtain the front surface light of the contact lens for correcting the wavefront aberration of the wavefront. The optimal ring-surface type of the area of the cornea is obtained. The surface-type structure of the anterior and posterior surface optical areas of the designed corneal contact lens is calculated and fitted to obtain the most optimal contact lens for the cornea. Excellent ball, column degree, and astigmatic axis position angle. Comparison of the power of the tear mirror before the person's eye wave It is proved that the results of this method are credible. Compared with the precision of 0.125D of the traditional mirror, the result of this chapter is obtained in this chapter. The photometric accuracy is only 0.04D. In order to obtain the nerve-contrast sensitivity function of the human eye at the time frequency, the contrast sensitivity function at the full-eye time frequency is according to the correlation between the contrast sensitivity function and the modulation transfer function, the time frequency is obtained by numerical calculation, The results of the test show that, with the increase of the time frequency, the whole curve of the neural-contrast sensitivity function is greatly reduced, and a similar 鈥渨ith one's mouth鈥

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