主客观结合人眼波前像差测量系统的设计与实验

设计了主客观方法相结合的人眼波前像差测量系统。该系统的控制部分以工控机为中心,实现了对离焦补偿装置、LCD视标显示装置和可变形镜驱动器的控制。使用Hartmann-Shack传感器对人眼出瞳的波前像差进行测量,光路中加入了能够显示各种视标和测试图案的LCD,从而考虑到了主观调节对人眼像差的影响,能够对人眼的视觉质量进行全面衡量,实现了客观测量和主观测量在光路中的结合。使用该系统分别测量得到了模拟眼和活体人眼的波前像差,并对主客观测量结果进行了信息融合,能够为个性化的人眼屈光矫正提供有用的依据。     

在测量人眼像差中信息融合方法的应用

建立了基于Hartmann-Shack传感器的主客观人眼波前像差测量系统,该系统使用Hartmann-Shack传感器客观测量人眼像差,分别对模拟眼和活体人眼进行了像差测量.同时系统中加入了主观测量人眼像差的部分,该系统能够同时进行客观和主观的像差测量,实现了使用信息融合的方法对测量结果进行数据处理.并结合了客观测量和主观测量的优点,使用信息融合的方法使测量结果更加合理.     

主客观相结合眼波面像差分析系统

利用Hartmann-Shack波面传感器对眼出瞳位置的波面像差进行测量,根据所测像差控制可变形镜对像差进行实时补偿.眼像差以Zernike多项式表示,通过对可变形镜的精确控制,可在光路中生成特定模式和幅值的像差.因此,被测者根据视觉的主观感觉,调节视标像差,直至获得最满意的视觉效果.该系统采用移动三棱镜和柱镜的方法对离焦和散光进行预补偿,弥补了波面传感器测量范围和可变形镜矫正范围受限制的缺点.该系统把快速、客观的测量及补偿和主观调整相结合,更加符合人眼工作的特性,可用于在人眼像差与视觉分辩的基础和临床研究.     

基于人眼光学质量的球差和离焦补偿关系研究

基于人眼光学质量客观评估方法,通过实测的屈光手术前后人眼波前像差数据,研究和分析了球差与离焦的补偿关系。结果表明,对于屈光手术前的近视眼患者,离焦与球差的补偿关系并不明显。对于屈光手术后的近视眼患者,离焦与球差的补偿关系明显,残余离焦可以部分补偿由于高阶像差增加引起的视功能降低。当残余离焦处于0.27D～0.74D范围内,离焦与高阶像差组合后,光学质量提高了20%以上。在屈光手术方案设计时,预留0.27D～0.74D的离焦时,可以使80%的人眼达到更好的视觉矫正效果。     

一种新型人眼波前像差测量补偿系统的研究

离焦是人眼中最主要的像差之一,离焦量过大会严重影响人眼波前像差的测量及矫正精度。为了消除离焦在此方面带来的影响,设计了带有补偿装置的人眼波前像差测量及矫正系统。重点分析了该系统的原理、结构和工作流程。运用Hartmann-Shack波前传感器测量了人眼波前像差,并使用变形反射镜对人眼波前像差进行矫正。对模拟人眼矫正离焦前后的光斑点阵图和波前三维重构图进行了对比分析。研究表明,通过离焦补偿系统对模拟人眼的离焦量进行矫正,使被测量人眼的离焦量由2.020D和-2.035D分别减小到0.011D和-0.007D;通过调焦系统,使显示器上显示出的人眼光斑点阵图由模糊变清晰,提高了信标光在人眼眼底的成像质量。     

二次曲面前房型有晶体眼人工晶体的球差矫正特性分析

为探究二次曲面前房型有晶体眼人工晶体的球差矫正特性,进行了球面和二次曲面有晶体眼人工晶体的设计,并利用像差理论对二者的球差矫正特性进行了研究.基于R.Navarro等人提出的模型眼得到屈光不正眼模型,利用ZEMAX光学软件分别设计了可矫正屈光不正人眼的球面与二次曲面前房型有晶体眼人工晶体.通过对光学传递函数和Zerni...     

矫正器平移和旋转对人眼高阶像差矫正的容限分析

人眼像差矫正器的位置变化对矫正人眼像差能力的容限分析有重要的意义.在基于哈特曼-夏克人眼像差仪对三只人眼像差准确测量的基础上,比较了人眼高阶像差矫正器与人眼低阶像差矫正器矫正效果的不同,从理论上计算了在平移和旋转下高阶像差矫止器矫正效果优于低阶像差矫正器的移动容限.三组被测试像差对旋转的容限均在20°左右,而对平移的容限差异较大.结果表明,位置变化对不同的像差有着不同的影响,人眼波前像差越大对位置变化越敏感,高阶矫正优势越不明显;高阶像差矫正对不同类型的位置变化有不同的容限度.其中平移的容限较小而旋转的容限较大.     

可诱导人眼自主调节的动态像差测量仪

研究了人眼在近视力状态下自动调节产生的动态像差。采用哈特曼-夏克(Hartmann-Shack,H-S)原理研制了一套可诱导人眼屈光调节,并能测量不同调节状态下人眼像差的测量仪。诱导原理为用视标在人眼近距离范围内移动以诱发人眼屈光调节,哈特曼-夏克传感器同时进行像差的测量,可以获得人眼调节时的视觉信息。与干涉仪测量同一像差板进行相比,像差仪的测量精度均方根(RMS)值为λ/50,重复性为λ/500,具有较好的测量精度和重复性。在测量的10人19只眼中,最大的诱发调节幅度为8.6D,一般可诱发调节幅度为3~8D之间,占总人数的84%。     

角膜手术后眼模型的构建和人工晶状体设计

根据角膜屈光手术前的角膜地形图、眼内各组分的轴向间距和波前像差,运用ZEMAX光学设计软件,构建了术前的个性化眼模型.结合角膜屈光手术后实际测量的波前像差,建立了术后个性化眼模型.运用该模型,为角膜屈光手术眼设计了双球面人工晶状体.研究表明:对于角膜屈光手术后人眼,用术后个性化眼模型计算的人工晶状体度数可靠.该模型还能够为术后眼设计矫正像散和其他高阶像差的人工晶状体,同时可以用来评估角膜手术联合白内障术后人眼的光学性能,以及手术中各类偏差对视觉质量的影响.     

基于波前曲率的客观验光新方法

波前像差的客观验光准确度对眼科临床应用有重要的意义。基于实测人眼的波前像差数据,计算波前像差曲面图的曲率分布,得到人眼在瞳孔平面位置的屈光度。通过波前传播,计算得到眼镜镜片所处位置的屈光度。该方法包含了高阶像差对人眼屈光度的影响,分析该屈光度与主观验光屈光度间的差异发现,4 mm瞳孔直径下的波前验光结果与主观验光结果差异较小,平均球度差异为0.06D,平均柱度和柱度角的差异分别为-0.07D和0.62°。结果表明,利用4 mm瞳孔直径下的曲率分布图验光结果可以较准确的预测主观验光结果。     

Information fusion method for ocular aberrations measurement based on subjective visual compensation

The human eye is an imperfect refractive system which not only has defocus and astigmatism, but also has spherical aberration, coma and anomalistic high-order aberrations, all of which have certain influence on the imaging quality of retina. What's worse, aberration is further enlarged as a result of mydriasis in dark field and weak light, thus making the vision performance of human eyes far below diffraction limitation. Further research revealed that human eye visual imaging is not only connected with refractive system, but also is closely related to the subjective judgment of human brain and the process of neural system. In order to overcome the deficiencies, wave-front aberration measurement method and system that has subjective visual compensation is proposed and conducted in combination with objective measurement, which ensures more accurate and realistic measuring results. The experimental data revealed that wave-front aberration obtained from subjective visual compensation measuring method is smaller than objective measurement, which is the result of subjects’ adaptive correction when watching sighting targets. In addition, when subjects are watching different sighting targets, the fluctuation value of wavefront aberration is small. Therefore, it is concluded that subjective visual compensation measuring method contributes to aberration measuring improvement and obtains results match with the realistic state by taking into consideration the actual condition of human eyes when watching targets. Hopefully, these discoveries will be of positive and beneficial value to the determination of human eye aberration treatment.     

Influence of refractive correction on ocular dominance

We investigated the effects of refractive correction and refractive defocus on the assessment of sensory ocular dominance. In 25 healthy subjects (4 males and 21 females) aged between 20 and 31 years, a quantitative measurement of sensory ocular dominance was performed with refractive correction and the addition of a positive lens on the dominant eye. Sensory ocular dominance was measured with a chart using binocular rivalry targets. The reversal point changed after the addition of a +1.00 D lens on the dominant eye in all subjects. However, sighting ocular dominance and stereopsis did not change after the addition of a positive lens on the dominant eye (P > 0:05, Wilcoxon test). These results suggest that refractive correction affects sensory ocular dominance, indicating the possible development of a new type of occlusion for amblyopia in the future.     

用于复色哈特曼人眼波像差测量的折/衍混合调焦系统

设计了一个折/衍混合多色调焦系统,可用于哈特曼波前传感器测量不同波长下人眼的波像差.系统由两片折射透镜和一个二元衍射面构成,焦距调整范围为－200～200 mm.系统性能达到衍射受限,在0.488～0.655 μm波长范围内,焦点色位移小于3 μm.整个系统结构简单、紧凑,同哈特曼波前传感器相匹配,可用于普通人群眼波像差的测量.     

Fresnel-based analysis of Kasprzak's crystalline model: statistical results and individual predictions

We present a new modelization technique of the human eye based on the calculation of light distributions inside the eye. The method is applied to the study of the crystalline model proposed by Kasprzak and Popiolek. We obtain corneal surface data and axial lengths for two groups of real eyes. With these data, we construct a diffractive model of a human eye, which permits calculation of propagated light distributions at any distance inside the eye. The real crystalline lens is substituted by Kasprzak's model, thus obtaining a realistic model eye. From calculated patterns, we obtain the Strehl ratio and the modulation transfer functions of 44 eyes, divided in two groups according to the age. We compare our results with those in the bibliography. Finally, we check the performance of the method through individual comparison of the calculated image positions with respect to the retina with the refractive data for the each subject. We have observed good agreement between our method and results from other authors. We also find reasonable correlation between calculated refraction and subjective exams.     

The biomechanical modelling of the refractive surgery

A study reports the numerical modelling of corneal-shaped sculpting according to simulation of the refractive surgery to verify biomechanical as well as geometrical parameters of the eye and to obtain the expected changes in the refractive power of the eyeball model.The finite-element method (FEM) was used to simulate an effect of refractive surgery. The corneal ablation and deformation for myopia correction were modelled.The refractive correction has an insignificant sensitivity on the assumed eccentricity of the corneal anterior profile across the range e=0-0.5. The expected correction occurs for corneal Young's modulus E_C?2 MPa. The including elasticity of the Descemet membrane E_D=2E_C or 5E_C has an insignificant influence on the refraction correction of the cornea with E_C>2 MPa, and has a greater influence for E_C<1 MPa.The understanding of the relationship between geometry, material properties and intraocular pressure (IOP) applied on the human eye has an importance for results of the refractive surgery. Numerical calculations showed that modelled dynamics of the eye is important for obtaining quantitative information about the biomechanical parameters of the biological eye tissues and permits its modelling before refractive surgery.     

用SVGA1薄膜晶体管液晶显示器矫正人眼波像差

在研究了SVGA1薄膜晶体管液晶显示器（TFT LCD）的位相调制特性的基础上,用它作为眼波像差的矫正器件,在用哈特曼-夏克波前传感器的眼像差测量系统中对眼波像差进行了成功的矫正.对于5.2 mm的瞳孔,矫正后人眼波像差的PV值降低了3倍多,并接近瑞利判据的像差容限.对系统的光学传递函数(MTF)的分析说明,经波像差矫正后眼的空间分辨率由17 c/deg提高到38 c/deg.     

Purkinje imaging system to measure anterior segment scattering in the human eye

We present an instrument based on Purkinje imaging that permits the objective measurement of the amount of scattering associated with the eye's anterior segment, avoiding the contribution from the retina. The experimental system records the fourth Purkinje image, and adequate processing is used to compute a parameter that quantifies the scattering. The method was first tested in an artificial eye and later in normal young eyes wearing customized contact lenses that induced different amounts of scatter. We were able to detect scattering increments, which indicates that this technique may be used as an objective tool to quantify the level of scattering in the anterior segment of the living human eye. The future use of this technique in clinical environments might help to estimate the level of corneal haze in eyes undergoing refractive surgery or/and scattering within the lens during cataract development.     

超视力人眼模型的研究

超视力人眼模型对充分发掘人眼视力达到“鹰视”具有重要意义。用Zernike多项式描述角膜前表面，用渐变折射率描述晶状体的折射率分布，同时考虑人眼视轴和光轴的夹角对成像的影响，利用光学设计软件Zemax建立了人眼超视力模型。将Zernike条纹矢高面应用到人眼模型中，能有效改变视轴方向(即5°视场)的成像质量，提高点扩散函数（PSF）值。采用晶状体渐变折射率符合人眼的实际解剖结构，可有效减小人眼像差。通过分析人眼极限分辨能力和人眼模型波像差，得出当空间频率为60周期/度时，该模型对目标高频细节感知的调制度可达到0.55。     

Closed-loop adaptive optics in the human eye

We have developed a prototype apparatus for real-time closed-loop measurement and correction of aberrations in the human eye. The apparatus uses infrared light to measure the wave-front aberration at 25 Hz with a Hartmann-Shack sensor. Defocus is removed by a motorized optometer, and higher-order aberrations are corrected by a membrane deformable mirror. The device was first tested with an artificial eye. Correction of static aberrations takes approximately five iterations, making the system capable of following aberration changes at 5 Hz. This capability allows one to track most of the aberration dynamics in the eye. Results in living eyes showed effective closed-loop correction of aberrations, with a residual uncorrected wave front of 0.1microm for a 4.3-mm pupil diameter. Retinal images of a point source in different subjects with and without adaptive correction of aberrations were estimated in real time. The results demonstrate real-time closed-loop correction of aberration in the living eye. An application of this device is as electro-optic "spectacles" to improve vision.