基于周边屈光度的儿童眼光学模型构建及其应用研究

Peripheral optical components have been found to be associated with myopia progression. Peripheral optical components involve two concepts, refraction (defocus and astigmatism) and retinal image quality (aberration, scatter and diffraction). Change in peripheral defocus alone can significantly slow myopia progression in animals, but has obtained only partial success in humans. This suggests that peripheral optical components such as astigmatism, aberration and diffraction in humans might be prominent after the correction of defocus, then affect peripheral retinal image quality, and finally influence myopia progression in humans. The applicant has recently found that the peripheral refractions of children in central China have similar patterns, but lower magnitudes as those of other races. Does peripheral retinal image quality mainly influence the myopia progression in Chinese children? In this project, the applicant plans to (1) use optical software to establish optical models of children based on peripheral refraction, to follow up these children annually for 3 years and then optimize the optical models based on changes in refraction. (2) With these optical models and Fourier transformation, retinal image quality (point spread function, modulation transfer function, and Strehl ratio) at different optical wavelengths, field angles and pupil sizes can be obtained. The influences of these factors on peripheral retinal image quality could be identified.(3) evaluate the variation tendency of peripheral retinal image quality and their effects on myopia progression after adjusting of near work visual load and time spent in outdoor activities in children, then provide theoretical basis for intervention strategies for myopia.

周边光学信号被发现与近视进展相关。光学信号涉及屈光度（离焦、散光）和视网膜像质（像差、散射和衍射）两层概念。仅改变周边离焦能显著延缓动物近视进展，在人类仅获部分成功，提示人眼周边光学信号如散光、像差和衍射等可能在矫正离焦后突显，影响了周边视网膜像质并导致人类近视进展。申请者最近研究发现，我国中原地区儿童的周边屈光度与其他人种相比模式相似幅度较小。是否周边视网膜像质主要影响了我国儿童的近视进展？本项目拟（1）采用光学软件建立基于周边屈光度的儿童眼光学模型，随访儿童3年并根据屈光变化值逐步优化模型；(2)由光学模型经傅里叶转换获得不同个体在不同光波长、视场角和瞳孔大小下的周边视网膜像质（点扩散函数、调制传递函数和斯特列尔比），明确上述因素对周边视网膜像质的影响程度；(3)综合评估周边视网膜像质的变化趋势及其在校正儿童近距离视负荷和户外活动时间后对近视进展的影响，为近视的干预治疗提供理论依据。

周边屈光度被发现与近视密切相关，但近期研究提示，周边视网膜像质可能也有作用，构建出基于周边屈光度的儿童眼光学模型有助于回答此问题。本项目基于前期基础，即已建立的3000多名小学生眼部数据库，采用ZEMAX软件构建符合我国儿童眼球特点和周边屈光度的眼光学模型；通过此模型研究了视场角和瞳孔大小对周边视网膜像质的影响，探讨了周边视网膜像质与儿童近视进展的关系。项目按照原计划顺利完成，结果如下。.1.构建了7岁儿童的正视眼眼光学模型，该模型眼的总屈光力为62.55 D，眼轴长度23.03 mm，该模型可作为儿童眼正视化和近视研究的参考工具。眼光学模型的光学参数为：角膜前表面曲率半径7.78 mm，非球面系数-0.18；后表面曲率半径6.4 mm，非球面系数-0.60；厚度0.54 mm，折射率1.376。前房深度3.00 mm，房水折射率1.336。晶状体前表面曲率半径12.4 mm，非球面系数-0.94；后表面曲率半径-8.1 mm，非球面系数0.96；厚度3.55 mm，折射率为梯度渐变折射率。玻璃体厚度15.94 mm，折射率1.336。视网膜曲率半径-12.3 mm，眼轴长度23.03 mm，总屈光力62.55D。.2.构建了7岁儿童、14岁儿童、7岁男童、7岁女童、14岁男童和14岁女童共计6套三表面近轴眼光学模型。这些模型眼随年龄增加而变化的参数包括前房深度加深、晶状体厚度减小、玻璃体腔长度增加、眼轴长度增加、晶状体前曲率增加以及晶状体屈光力下降。男童模型眼比女童模型眼具有较深的前房深度、较长的玻璃体腔长度、较长的眼轴长度、较大的晶状体前曲率和较低的晶状体屈光力。.3.以构建的儿童眼模型进行分析，入瞳直径为2 mm～8 mm，以1 mm为间隔，眼光学模型的波前像差PV值分别为0.017、0.182、0.660、1.579、2.904、4.367、5.302微米，RMS值分别为0.005、0.053、0.199、0.486、0.901、1.401、1.827微米，均随入瞳直径增大而变大；MTF曲线下面积随入瞳直径增大而变小。周边视网膜像质与儿童近视进展之间没有显著相关性。.本项目构建的儿童眼光学模型是首个基于我国儿童队列数据，可用于分析眼部不同参数、不同环境下的眼部光学特点，可以比较其他具有相同或不同种族背景和不同生活地点的儿童，为儿童近视研究提供了一种有力工具。