复曲面人工晶状体成像质量实验研究

发布时间：2018-05-12 18:53

本文选题：晶状体 + 人工　；参考：《河北医科大学》2013年博士论文

【摘要】：角膜散光是一种常见的屈光不正，约有20%的白内障患者角膜有不同程度的散光。在白内障手术中控制术后散光，一直是手术医生关注的问题。通过白内障手术切口的设计可以简便有效的矫正低度散光，但这种方法的可预测性较差，并且随着白内障手术技术的不断进步，手术切口越来越小，可以提供矫正散光的效果越小。不同技术的角膜松解切口术也可以用于手术中矫正角膜散光，主要缺点是稳定性差，有出现角膜穿孔，甚至切口组织溶解的危险，限制了其在临床的应用。散光型人工晶状体（intraocular lens，IOL）是一种将散光的toric面与球面相融合新型屈光型IOL，目前临床研究表明，Toric IOL能有效地矫正角膜散光提高裸眼视力。对不规则的角膜散光-圆锥角膜、角膜移植术后、角膜外伤瘢痕等，使用Toric IOL仍然能矫正部分散光使患者视力获得一定程度提高。复曲面IOL虽然在屈光度上能有效矫正角膜散光，提高患者视力，但其复杂的光学结构使其在很多方面的光学质量仍然存在双眼径线成像不等大的融合问题、径线屈光度差异对Toric IOL焦深、纵向色差的影响等疑问；同时Toric IOL不可避免存在偏心、倾斜和散光轴位旋转等位置误差对IOL成像质量的影响是目前探讨的热点。随着波前像差技术的进步人工晶状体眼的像差的认识及矫正使IOL成像质量进一步提高，患者的视觉质量获得更大的改善。对于Toric IOL进行光学结构的改进，优化球差(sphrecial aberration, SA)，是否能获得和球面IOL相同的光学质量的提高？由于Toric IOL存在着比旋转对称的IOL更多的误差指标，如何使Toric IOL光学质量提高同时拥有对误差更好的耐受性是本研究的目的。第一部分基于模型眼复曲面人工晶状体成像质量实验研究目的：评价复色光环境下球面、非球面、Toric IOL的成像质量、焦深及纵向色差。方法：在Zemax光学设计软件中建立Hwey-Lan Liou模型眼，使用光线追迹法计算，评价TecnisZA9003IOL、SN60AT IOL、Toric IOL复色光的成像质量、纵向色差和焦深。结果：复色光环境下非球面IOL成像质量仍然优于球面IOL; ToricIOL与球面IOL有相近的成像质量。材料色散系数小的IOL有较小的纵向色差；球面SN60AT和Toric IOL有相同的纵向色差；短波长的光线的纵向色差大于长波长。球面IOL和Toric IOL随着瞳孔直径增大离焦调整传递函数降低，并且向负离焦方向偏移；非球面IOL随着瞳孔直径增大保持较好的离焦调制传递函数，但焦深明显减小。 0小结：（1）Toric IOL有与球面IOL相近的成像质量。（2）Abbe数越大，IOL的纵向色差越小。（3）Toric IOL、球面IOL和非球面IOL的焦深随着瞳孔直径的增大而减小；而且Toric IOL、球面IOL对负离焦耐受较好。（4）非球面IOL对离焦的耐受性较低，焦深较小。第二部分复曲面人工晶状体偏心及旋转对成像质量影响的实验研究目的：评价Toric IOL旋转偏心对成像质量的影响和波前像差的改变。方法：模型眼中550nm波长单色光，研究SN60AT和Toric IOL分别沿从0o~90o每间隔5o子午线从中心偏离，分别偏心0.25mm、0.5mm、0.75mm， Toric IOL在模型眼中旋转3o、5o、7o、10o，评价偏心和旋转对的成像质量和波前像差的影响及旋转对残留屈光度的影响。结果：在IOL居中SN60AT IOL与Toric IOL的成像质量非常接近，并且都随着瞳孔直径的增大成像质量降低；在轴位准确，散光完全矫正的情况下，Toric IOL偏心不受方向的影响，沿0o~90o各子午线屈光力不同方向偏心时成像质量几乎保持不变。 SN60AT IOL与Toric IOL随着偏心增加RMS逐渐增大，主要是彗差的增加，伴随少量三叶草像差和散光的增加。随着Toric IOL旋转的增加，高空间频率成像质量降低明显；ToricIOL旋转主要引起散光的增大，不伴有高阶像差的增加。Toric IOL旋转不但造成残留散光的增加，还伴有球镜的增大。小结：（1）Toric IOL成像质量略低于球面IOL; Toric IOL偏心成像质量不受偏心方向的影响，只与偏心量有关；Toric IOL对偏心的耐受性与球面IOL非常接近。（2）Toric IOL偏心引起波前像差的变化主要是彗差增加，同时有少量散光和三叶草像差的增加。（3）Toric IOL旋转带来散光和球镜的增加，不伴有高阶像差的增加。第三部分复曲面人工晶状体优化及对成像质量影响的实验研究目的：对于Toric IOL的球差进行优化，设计不同球差的Toric IOL，并且对不同球差Toric IOL的旋转、偏心的耐受性及成像规律进行研究。方法:模型眼中在550nm波长单色光条件下，对复曲面人工晶状体进行两个步骤的优化：1.复曲面人工晶状体球面结构的优化，，优化函数设定人工晶状体前、后表面曲率半径和厚度为可变参量，以ZERN函数第11项C04最小为目标进行优化。2.复曲面人工晶状体球差的优化，优化目标设计为：-0.26μm、-0.1μm和0μm球差的复曲面人工晶状体。优化函数设定ZERN函数第11项分别以C04为0μm、0.16μm、0.26μm为目标，对人工晶状体前表面Q值和2、4阶非球面系数进行优化。球面和非球面Toric IOL在模型眼中沿x轴分别偏心0.25mm、0.5mm、0.75mm，评价其成像质量和波前像差的改变；；旋转3o、5o、7o、10o，评价其对成像质量及波前像差影响。球面和非球面Toric IOL在模型眼中分别在3mm、4mm、5mm瞳孔直径随机偏心0~0.5mm，旋转0o~5o，进行1000次模拟，结果进行蒙特卡洛分析。结果：居中时非球面Toric IOL都有非常好的成像质量，明显优于球面结构的Toric IOL，随着瞳孔直径的增大更加明显。3mm瞳孔偏心0.25mm，球面和非球面Toric IOL都有与居中时相近的MTF，对0.25mm偏心的耐受较好。偏心0.5mm时，-0.26μm球差的Toric IOL的成像质量下降并且低于0μm球差和-0.1μm球差的IOL。偏心0.75mm时，0μm球差的Toric IOL在中低空间频率优于其他IOL。4mm瞳孔偏心0.25mm时，-0.1μm球差的Toric IOL成像质量最好。偏心0.75mm时-0.1μm球差的Toric IOL优于球面和其他非球面Toric IOL。5mm瞳孔直径时，偏心0.25mm时-0.26μm球差的Toric IOL中低空间频率优于其他Toric IOL，高空间频率MTF与0μm球差和-0.1μm球差的IOL接近。偏心0.75mm时-0.26μm球差IOL的MTF与球面Toric IOL接近，0μm球差和-0.1μm球差的IOL略优于球面Toric IOL。小结：(1)居中时非球面Toric IOL能有效的提高模型眼的光学质量；-0.26μm球差的Toric IOL成像质量最好。(2)存在偏心和旋转误差时非球面Toric IOL的成像质量仍然优于球面Toric IOL，-0.1μm球差的Toric IOL即有较好的成像质量，又有较好的对误差的耐受性。(3)对Toric IOL球差适量的优化，可以提高模型眼的成像质量，同时保持对偏心和旋转误差的耐受性，在综合情况下获得更好的光学质量。第四部分复曲面人工晶状体个体化模型眼成像质量的实验研究目的：采集患者眼部解剖参数，利用Zemax光学设计软件建立个体化模型眼，研究不同球差的Toric IOL植入后的视觉质量。方法：Pentacam采集患者手术前的角膜地形图。IOLMaster测量患者眼轴长。Matlab4.5数学计算软件中采集5×5mm范围角膜前表面高度图数据使用最小二乘法根据双二次曲线方程进行拟合，建立前角膜表面散光模型，采集5×5mm范围角膜后表面高度图数据根据二次曲线方程拟合建立角膜后表面模型。在Zemax光学设计软件构建个体化模型眼。散光角膜模型的平坦轴置于y轴，陡峭轴置于x轴；角膜厚度使用该例角膜地形图中央最薄点厚度数据；IOL的前表面置于相应的ELP（effective thin-lensposition，ELP）。在550nm波长条件下，计算个体化模型眼6mm直径角膜球差（sphericalaberration，SA）。强光环境（300Td），瞳孔直径为3mm；暗光环境（0.3-1Td），瞳孔直径为5mm；根据两种条件下的神经传递函数,计算每一个模型眼的对比敏感度。结果：个体化模型眼角膜前表面平坦轴Q值：-0.12±0.22；陡峭轴Q值：-0.12±0.23；后表面Q值：-0.43±0.37；角膜平均球差为：0.23μm±0.18μm（-0.15μm~0.42μm）。强光环境非球面Toric IOL的RMS和球差都优于球面IOL；全矫球差的Toric IOL对比敏感度在各空间频率都优于其他IOL。暗光环境非球面Toric IOL的RMS和球差也优于球面IOL；全矫球差的Toric IOL在中高空间频率都优于其他IOL，低空间频率与其他球差的非球面Toric IOL对比敏感度差异无统计学意义。小结：（1）角膜高度数据对双二次曲面公式的拟合可以准确建立角膜散光模型。（2）非球面Toric IOL能有效的抵消散光角膜球差，提高个体化模型眼大部分空间频率的对比敏感度。结论： 1Toric IOL与球面IOL有相近的成像质量及离焦特性。 2Toric IOL与球面IOL对偏心的耐受性也相近。偏心造成波前像差的变化主要是彗差的增加。Toric IOL的旋转主要造成散光的增加，不引入高阶像差。 3对Toric IOL球差适量的优化，可以提高的成像质量，同时保持对偏心和旋转误差的耐受性，在综合情况下获得更好的光学质量。 4角膜高度数据对双二次曲面公式的拟合可以准确建立个体化角膜散光模型。
[Abstract]:The corneal astigmatism is a common refractive error , and about 20 % of the cataract patients have different degrees of astigmatism .

The astigmatic intraocular lens ( IOL ) is a new type of refractive - type IOL combining astigmatism with spherical phase . At present , the clinical study shows that the Toric IOL can effectively correct corneal astigmatism and improve the visual acuity of the naked eye . The Toric IOL can correct some astigmatism after the irregular corneal astigmatism - cone cornea , corneal transplantation , corneal trauma scar , etc . The patient ' s vision is improved to a certain extent .

Although the complex surface IOL can effectively correct corneal astigmatism and improve the visual acuity of the patient , the complex optical structure still has large fusion problems such as binocular radial line imaging in many aspects , and has some doubts about the influence of the refractive power difference on the focal depth and longitudinal chromatic aberration of the Toric IOL ;
At the same time , the influence of position error such as eccentricity , tilt and optical axis position on IOL imaging quality is inevitable in Toric IOL .

With the improvement of the optical structure of the Toric IOL , it is an object of this study to improve the optical quality of the Toric IOL and to improve the tolerance of the Toric IOL at the same time .

Experimental study on the imaging quality of the first part based on the model eye complex curved surface intraocular lens

Objective : To evaluate the imaging quality , focal depth and longitudinal chromatic aberration of spherical , aspheric , Toric IOL in complex light environment .

Methods : The image quality , longitudinal chromatic aberration and focal depth of the TecnisZA9003IOL , SN60AT IOL , Toric IOL composite light were evaluated by using the ray tracing method in the Zemax optical design software .

Results : The imaging quality of aspheric IOL was still superior to that of spherical IOL in compound light environment . Toric IOL had similar imaging quality with spherical IOL . IOL with small material dispersion coefficient had smaller longitudinal chromatic aberration ;
spherical SN60AT and Toric IOLs have the same longitudinal chromatic aberration ;
the longitudinal chromatic aberration of the short wavelength light is greater than the long wavelength . The spherical IOL and the Toric IOL are reduced from the focus adjustment transfer function with the pupil diameter and are shifted towards the negative focus direction ;
The aspheric IOL maintains a better off - focus modulation transfer function as the pupil diameter increases , but the depth of focus is significantly reduced .

( 2 ) The larger the Abbe number , the smaller the longitudinal chromatic aberration of the IOL . ( 3 ) The focal depth of the Toric IOL , the spherical IOL and the aspherical IOL decreases with the increase of the pupil diameter ;
( 4 ) The tolerance of the aspheric IOL to the defocus is low and the depth of the focal depth is smaller .

Experimental study on the influence of the eccentricity and rotation of the second part complex curved intraocular lens on the imaging quality

Objective : To evaluate the effect of Toric IOL rotation eccentricity on imaging quality and the change of wavefront aberration .

Methods : The 550 nm wavelength monochromatic light was observed in the model eye . The SN60AT and Toric IOL were deviated from the center along the 5o meridian from 0o to 90o , respectively , eccentric 0.25 mm , 0.5 mm , 0.75 mm , and Toric IOL were rotated 3o , 5o , 7o , 10o in the eye of the model . The effects of eccentricity and rotation on the imaging quality and wavefront aberration and the effect of rotation on residual power were evaluated .

Results : The imaging quality of the IOL centered SN60AT IOL was very close to the imaging quality of the Toric IOL and decreased with increasing pupil diameter ;
Under the condition that the axial position is accurate and the astigmatism is completely corrected , the eccentricity of the Toric IOL is not influenced by the direction , and the imaging quality is almost unchanged when the optical power of each meridian of 0o - 90o is eccentric in different directions .

The SN60AT IOL and the Toric IOL gradually increase with the increase of the eccentricity , mainly the increase of coma , accompanied by a small amount of clover aberration and the increase of astigmatism .

With the increase of Toric IOL rotation , the quality of high spatial frequency imaging was reduced ;
Toric IOL rotation mainly results in an increase in astigmatism , not accompanied by an increase in higher order aberrations . Toric IOL rotation not only results in an increase in residual astigmatism but also an increase in the spherical mirror .

Summary : ( 1 ) The imaging quality of the Toric IOL is slightly lower than that of the spherical IOL ; the eccentric imaging quality of the Toric IOL is not affected by the eccentric direction , and is only related to the eccentric amount ;
Toric IOL ' s tolerance to eccentricity is very close to the spherical IOL . ( 2 ) The variation of wavefront aberration caused by the eccentricity of the Toric IOL is mainly the increase of coma aberration , while a small amount of astigmatism and the increase of the aberration of clover . ( 3 ) Toric IOL rotation brings astigmatism and increased spherical mirror , without the increase of higher order aberration .

Experimental study on the optimization of the third part complex curved surface intraocular lens and its effect on imaging quality

Objective : To optimize the spherical aberration of Toric IOL and to design Toric IOL with different spherical aberration .

Methods : In the eye of the model , the optimization of two steps : 1 . The optimization of the spherical structure of the complex curved lens was carried out . The curvature radius and thickness of the anterior and posterior surface of the artificial lens were optimized by the optimization function . The optimal objective was as follows : - 0.26 渭m , - 0.1 渭m and 0 渭m spherical aberration . The optimal objective was designed as : - 0.26 渭m , - 0.1 渭m and 0 渭m spherical aberration .

The spherical and aspheric Toric IOLs were respectively eccentric 0.25 mm , 0.5 mm and 0.75 mm in the eye of the model along the x - axis , and the imaging quality and wavefront aberration were evaluated .
Rotate 3o , 5o , 7o , 10o to evaluate its impact on imaging quality and wavefront aberration .

The spherical and non - spherical Toric IOLs were randomly eccentric 0 ~ 0.5mm and rotated 0o ~ 5o at 3mm , 4mm , 5mm pupil diameter in the eyes of the model . The results were analyzed by Monte Carlo .

Results : Toric IOLs with spherical aberration of 0.25 mm and 0 渭m were superior to those of other Toric IOLs in the middle and low spatial frequencies .

Summary : ( 1 ) The aspheric Toric IOL can effectively improve the optical quality of the model eye .
( 2 ) The imaging quality of the aspheric Toric IOL is superior to that of spherical Toric IOL , - 0.1 渭m spherical aberration Toric IOL , which is superior to spherical Toric IOL , - 0.1 渭m spherical aberration Toric IOL , which has better imaging quality and better tolerance to error .

Experimental study on the quality of eye imaging of the fourth part complex curved intraocular lens

Objective : To study the visual quality of Toric IOL implanted with different spherical aberration by using Zemax optical design software to establish a personalized model eye .

Methods : The corneal topography before operation was collected from Pentacam . The corneal anterior surface height map data collected in the Matlab4.5 mathematical calculation software was fitted with the biquadratic curve equation . The corneal posterior surface model was established by fitting the corneal posterior surface height map data with the quadratic curve equation .
the thickness of the cornea is the thinnest point thickness data of the cornea topography of the case ;
the anterior surface of the iol is placed in a corresponding elp ( effective thin - position position , elp ) .

The spherical aberration ( SA ) of 6 mm diameter was calculated at 550 nm wavelength .

Strong light environment ( 300Td ) , pupil diameter is 3mm ;
Dark light environment ( 0.3 -1Td ) , pupil diameter is 5mm ;
The contrast sensitivity of each model eye was calculated based on the nerve transfer function under both conditions .

Results : The Q value of the anterior surface of the corneal anterior surface was 0.12 卤 0.22 ;
The Q value of the steep axis is - 0.12 卤 0.23 ;
Rear surface Q value : - 0.43 卤 0.37 ;
The mean spherical aberration of cornea was 0.23 渭m 卤 0.18 渭m ( - 0.15 渭m ~ 0.42 渭m ) .

The RMS and spherical aberration of the aspheric Toric IOL in the strong light environment are superior to those of the spherical IOL ;
Toric IOL contrast sensitivity was superior to other IOLs at all spatial frequencies . The RMS and spherical aberration of aspheric Toric IOLs were also superior to spherical IOLs .
Toric IOLs with all - corrected spherical aberration were superior to other IOLs at medium and high spatial frequencies , with no statistically significant difference in contrast sensitivity between low spatial frequencies and other spherical Toric IOLs .

Conclusion : ( 1 ) The fitting of the corneal height data to the double quadratic surface formula can accurately establish the corneal astigmatism model . ( 2 ) The aspheric Toric IOL can effectively counteract the astigmatic corneal spherical aberration and improve the contrast sensitivity of the most spatial frequency of the individual model eye .

Conclusion :

The 1 Toric IOL has similar imaging quality and defocus characteristics to the spherical IOL .

The tolerance of the 2Toric IOL and the spherical IOL is similar to that of the spherical IOL . The change of the wavefront aberration caused by eccentricity is mainly the increase of coma aberration . The rotation of the Toric IOL mainly causes the increase of astigmatism and does not introduce higher order aberrations .

3 To optimize the spherical aberration of Toric IOL , the quality of imaging can be improved , while the tolerance of eccentricity and rotational errors can be maintained , and better optical quality can be obtained under comprehensive circumstances .

The fitting of the corneal height data to the double quadratic surface formula can accurately establish the individualized corneal astigmatism model .

【学位授予单位】：河北医科大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R779.66

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