Accommodation-related changes in monochromatic aberrations of the human eye as a function of age

PURPOSE: To investigate the relationship between accommodation and the optical aberrations of the whole human eye, as a function of age. METHODS: Sixty healthy subjects with spherical ametropia in the range +/-3 D, astigmatism less than 1 D, corrected visual acuity of 20/18 or better, and normal findings in an ophthalmic examination were enrolled. Subjects were divided into four groups, with age ranges of 19 to 29, 30 to 39, 40 to 49, and 50 to 60 years. Monochromatic optical aberrations and pupil size were measured with a Hartmann-Shack wavefront sensor under monocular viewing conditions, without pharmacological dilation or cycloplegia. Stimulus vergences were in the range of 0 to 5 D, with an increment of 0.5 D. The change in aberration during accommodation for different groups and different pupil conditions (natural and fixed 4-mm pupil) was compared. RESULTS: Fourth-order spherical aberration (SA) became more negative with accommodation, and the rate of this change was greater in older individuals. For natural pupil conditions, there were no significant differences between age groups in the changes of the higher-order aberrations, coma, and trefoil with accommodation. However, for a 4-mm pupil, the youngest and oldest group showed significant differences in higher order RMS (root mean square) and spherical aberration compared with the other groups. High-order RMS showed a lower increase during accommodation when the pupil accommodative miosis was taken into account (natural pupil condition) than when a fixed 4-mm pupil was used. CONCLUSIONS: Aberrations change with accommodation and with age. SA changes more with accommodation do than other higher-order aberrations. SA becomes more negative with accommodation, and this change is larger in older individuals. Accommodative miosis is useful for ameliorating the increase in higher-order aberrations with accommodation.     

近视眼患者波前像差的分析研究

目的：对近视眼患者存在的波前像差进行相关因素分析。 方法：用波前像差仪对前来我院行LASIK手术的115例218眼进行波前像差的检查,并进行常规角膜屈光手术的各项术前检查,同时用对比敏感度检查表进行对比敏感度的检查,将各项结果分别与波前像差进行相关性分析。 结果：像差成分以低阶像差为主,高阶像差有明显的个体差异,最大值是最小值的62倍;术前像差和瞳孔直径呈正相关关系,即随着瞳孔直径的增加高阶像差增加;高阶像差与中频区对比敏感度存在弱的负相关性;波前像差和患者的屈光度的高低有关系;随着散光度数的增加,波前像差增加。术前像差各成分和性别无显著相关性。 结论：近视眼患者的波前像差受患者具体条件的影响,个性化手术去除波前像差应考虑周全。     

近距离计算机工作对不同类型近视眼波前像差的影响

背景 近视眼近距离工作时存在的调节异常及高阶像差均与视网膜图像模糊相关,因此研究稳定性和进展性近视眼近距离工作前后高阶像差的变化具有重要意义. 目的 观察进展性近视和稳定性近视在近距离工作,如计算机工作前后高阶像差的变化,同时评估不同类型近视眼高阶像差的变化.方法 采用病例对照研究设计.60例受试者按年龄、性别匹配的原则进入进展性近视组及稳定性近视组,每组各30例.使用框架眼镜矫正屈光不正,然后持续使用计算机1h,阅读距离为40 cm,暗环境、自然最大瞳孔状态下使用COAS波前像差仪测量右眼计算机工作前后的波前像差,分别导出3、4、5 mm瞳孔直径下各阶像差的变化,分析计算机工作和近视类型对波前像差的影响,各阶高阶像差(3～6阶)以均方根(RMS)表示.结果 直径3、4、5 mm瞳孔下受试者使用计算机工作前后高阶像差的差异均无统计学意义(均P＞0.05).直径3mm瞳孔时进展性近视和稳定性近视的高阶像差RMS差异均无统计意义(均P＞0.05);直径4 mm瞳孔下进展性近视3、5、6阶RMS和总高阶RMS显著高于稳定性近视,差异均有统计学意义(F=5.985,P=0.016;F=3.975,P=0.049;F=8.130,P=0.005;F=6.493,P=0.012);直径5 mm瞳孔下进展性近视3、5、6阶RMS和总高阶RMS显著高于稳定性近视,差异均有统计学意义(F=13.132,P=0.000; F=4.032,P=0.047;F=4.393,P=0.038;F=10.508,P=0.002).各瞳孔直径下进展性近视组球差均大于稳定性近视组,但差异均无统计学意义(P＞0.05).结论 进展性近视眼高阶像差大于稳定性近视眼,但近距离工作,如从事计算机工作,不引起近视眼高阶像差的显著变化.     

Influence of age on ocular wavefront aberration changes with accommodation

PURPOSE: To perform a quantitative analysis of high order wavefront aberrations of the entire optical system of the eye that accompanies accommodation demands in the healthy and emmetropic eye. METHODS: Fifty-six healthy emmetropic eyes of 30 patients were separated into three groups according to age: group 1, 20 to 29 years; group 2, 30 to 39 years; and group 3, 40 to 49 years. Using iTrace ray-tracing technology, pupil diameter, objective refraction, and wavefront aberrations at accommodation demands of 0 to 4.00 diopters (D) in five 1.00-D increments were determined. In analyzing higher order aberrations in the central 4-mm diameter zone of the pupil, Zernike polynomials were used to study the changes associated with accommodation in the magnitude of total higher order aberrations, third order aberrations (coma-like aberrations), fourth order aberrations (spherical-like aberrations), and the spherical aberration component (C4(0)) of the fourth order aberrations. RESULTS: Pupil diameter decreased significantly (P < .05) with accommodation demand in each group. Total higher order aberrations in group 1 increased significantly (P < .05). No significant change was seen in third order aberrations in any group, but fourth order aberrations increased significantly (P < .05) in group 1. Spherical aberration (C4(0)) showed phase shifts from positive to negative in all groups, but the shift in group 3 was minimal, remaining positive even for a 4.00-D accommodation demand. CONCLUSIONS: Among higher order aberrations accompanying accommodation demands, spherical aberration (C4(0)) in particular showed characteristic changes; however, these changes showed age-related disparities. The changes were probably due to the effects of reduction in accommodation resulting from age-related changes in the crystalline lens.     

Accommodation stimulus-response function and retinal image quality

Accommodation stimulus-response function (ASRF) and its relationship to retinal image quality were investigated using a modified wavefront sensor. Ten subjects were presented with six vergence stimuli between 0.17 D and 5 D. For each vergence distance, ocular wavefronts and subjective visual acuity were measured. Wavefronts were analysed for a fixed 3-mm pupil diameter and for natural pupil sizes. Visual Strehl ratio computed in the frequency domain (VSOTF) and retinal images were calculated for each condition tested. Subjective visual acuity was significantly improved at intermediate vergence distances (1D and 2D; p < 0.01), and only decreased significantly at 5 D compared with 0.17 D (p < 0.05). VSOTF magnitude was associated with subjective visual acuity and VSOTF peak location correlated with accommodation error. Apparent accommodation errors due to spherical aberration were highly correlated with accommodation lead and lag for natural pupils (R(2) = 0.80) but not for fixed 3-mm pupils (R(2) < 0.00). The combination of higher-order aberrations and accommodation errors improved retinal image quality compared with accommodation errors or higher order aberrations alone. Pupil size and higher order aberrations play an important role in the ASRF.     

Wavefront aberration and its relationship to the accommodative stimulus-response function in myopic subjects.

BACKGROUND: Autorefractors are increasingly used in myopia research because they are convenient tools to investigate aspects of the accommodation response. The degree to which the autorefractor measures are affected by ocular aberrations has been highlighted by studies that have shown changes in aberration levels through different parts of the pupil and with accommodation. We have compared accommodative accuracy as measured with a Shin-Nippon SRW 5000 autorefractor with wavefront error as measured with a Hartmann-Shack wavefront sensor to investigate how factors such as accommodation demand, ocular aberrations, and pupil size can influence autorefractor measures. METHODS: Accommodation stimulus-response curves were determined (using negative lenses) for 30 young healthy subjects (20 myopic [-0.75 to -6.00 D] and 10 emmetropic). Accommodation levels ranged from 0 to 4 D in 1 D steps. Wavefront aberrations were also determined for the same accommodation levels using a Hartmann-Shack wavefront sensor for both the subjects' natural pupil sizes and for a 2.9-mm pupil. RESULTS: For all subjects, there was a consistent increase in negative spherical aberration with increases in accommodative stimulus. However, there was no consistent change in paraxial spherocylindrical refractive correction with accommodation stimulus. For the emmetropic subjects, accommodation error as measured with the autorefractor was statistically similar to the total spherocylindrical correction for the eye as estimated by the Hartmann-Shack wavefront sensor, but only for a 2.9-mm pupil (the pupil size utilized by the autorefractor). For the myopic subjects, accommodation error as measured with the autorefractor was statistically similar to the higher-order aberrations, but only when measured for a natural pupil size. CONCLUSIONS: The relationship between the accommodation accuracy as measured with the autorefractor and the total wavefront aberration as measured with a Hartmann-Shack wavefront sensor is largely influenced by the higher-order (fourth and above) aberration levels. For the emmetropic subjects, the errors measured by the two methods agree when adjusted to measure at similar pupil sizes. For the myopic subjects with similar pupil sizes, however, the Hartmann-Shack wavefront sensor underestimates the accommodation error at higher accommodation levels (2 to 4 D) compared with the autorefractor.     

Effects of Zernike wavefront aberrations on visual acuity measured using electromagnetic adaptive optics technology

PURPOSE: This study measured the changes in visual acuity induced by individual Zernike ocular aberrations of various root-mean-square (RMS) magnitudes. METHODS: A crx1 Adaptive Optics Visual Simulator (Imagine Eyes) was used to modify the wavefront aberrations in nine eyes. After measuring ocular aberrations, the device was programmed to compensate for the eye's wavefront error up to the 4th order and successively apply different individual Zernike aberrations using a 5-mm pupil. The generated aberrations included defocus, astigmatism, coma, trefoil, and spherical aberration at a level of 0.1, 0.3, and 0.9 microm. Monocular visual acuity was assessed using computer-generated Landolt-C optotypes. RESULTS: Correction of the patients' aberrations improved visual acuity by a mean of 1 line (-0.1 logMAR) compared to best sphero-cylinder correction. Aberrations of 0.1 microm RMS resulted in a limited decrease in visual acuity (mean +0.05 logMAR), whereas aberrations of 0.3 microm RMS induced significant visual acuity losses with a mean reduction of 1.5 lines (+0.15 logMAR). Larger aberrations of 0.9 microm RMS resulted in greater visual acuity losses that were more pronounced with spherical aberration (+0.64 logMAR) and defocus (+0.62 logMAR), whereas trefoil (+0.22 logMAR) was found to be better tolerated. CONCLUSIONS: The electromagnetic adaptive optics visual simulator effectively corrected and generated wavefront aberrations up to the 4th order. Custom wavefront correction significantly improved visual acuity compared to best-spectacle correction. Symmetric aberrations (eg, defocus and spherical aberration) were more detrimental to visual performance.     

A population study on changes in wave aberrations with accommodation

Wave aberrations were measured with a Shack-Hartmann wavefront sensor (SHWS) in the right eye of a large young adult population when accommodative demands of 0, 3, and 6 D were presented to the tested eye through a Badal system. Three SHWS images were recorded at each accommodative demand and wave aberrations were computed over a 5-mm pupil (through 6th order Zernike polynomials). The accommodative response was calculated from the Zernike defocus over the central 3-mm diameter zone. Among all individual Zernike terms, spherical aberration showed the greatest change with accommodation. The change of spherical aberration was always negative, and was proportional to the change in accommodative response. Coma and astigmatism also changed with accommodation, but the direction of the change was variable. Despite the large inter-subject variability, the population average of the root mean square for all aberrations (excluding defocus) remained constant for accommodative levels up to 3.0 D. Even though aberrations change with accommodation, the magnitude of the aberration change remains less than the magnitude of the uncorrected aberrations, even at high accommodative levels. Therefore, a typical eye will benefit over the entire accommodative range (0-6 D) if aberrations are corrected for distance viewing.     

Aberrationen h?herer Ordnung bei Akkommodation

Background

Monochromatic aberrations may influence the visual acuity of the eye. They are not stable and can be affected by different factors. The subject of the following paper is the dynamic investigation of the changes in wavefront aberration with accommodation.

Method

Dynamic measurement of higher and lower order aberrations was performed with a WASCA Wavefront Analyzer (Carl-Zeiss-Meditec) and a specially constructed target device for aligning objects in far and near distances on 25 subjects aged from 15 to 27 years old.

Results

Wavefront aberrations showed some significant changes in accommodation. In addition to the characteristic sphere reaction accompanying miosis and changes in horizontal prism (Z₁ ¹) in the sense of a convergence movement of the eyeball also occurred. Furthermore defocus rose (Z₂ ⁰) and astigmatism (Z₂ ^?2) changed. In higher-order aberrations a decrease in coma-like Zernike polynomials (Z₃ ^?1, Z₃ ¹) was found. The most obvious change appeared in spherical aberration (Z₄ ⁰) which increased and changed from positive to negative. In addition the secondary astigmatism (Z₄ ^?2) and quadrafoil (Z₄ ⁴) rise also increased. The total root mean square (RMS), as well as the higher-order aberrations (RMS-HO) significantly increased in accommodation which is associated with a theoretical reduction of visual acuity. An analysis of the influence of pupil size on aberrations showed significant increases in defocus, spherical aberration, quadrafoil, RMS and RMS HO by increasing pupil diameter. By accommodation-associated miosis, the growing aberrations are partially compensated by focusing on near objects. Temporal analysis of the accommodation process with dynamic wavefront analysis revealed significant delays in pupil response and changing of prism in relation to the sphere reaction. In accommodation to near objects a discrete time ahead of third order aberrations in relation to the sphere response was found.

Conclusion

Using dynamic wavefront measurement achieved a sequential analysis of aberrations during accommodation. Significant changes in the lower and higher-order aberrations could be detected. These are additionally varied by the associated pupillary response. Moreover, the synchronicity of wave front reaction in the accommodation process was proven.     

瞳孔直径和调节刺激对年轻人正视眼单色高阶波阵面像差的影响

目的 探讨不同瞳孔直径下,调节对年轻正视眼单色高阶波阵面像差的影响.方法 干预性试验研究设计.使用光线追踪原理的波阵面像差仪测量12只年轻正视眼自然生理状态,在4.0、3.0、2.0 mm瞳孔直径下,0.00、1.00、2.00、3.00和4.00 D调节刺激下的单色波阵面像差.采用单因素方差分析及最小显著差法多重比较,对获得的数据进行统计学分析.结果 调节松弛下正视眼的总高阶像差、总彗差、总高阶散光、总球差和总三叶草像差的均方根值均随瞳孔直径减小而减小.在4.0、3.0、2.0mm瞳孔直径下,总彗差是调节松弛状态总高阶像差的最主要成分;总高阶像差仅在调节刺激达4.00 D时升高(P<0.05).瞳孔直径4.0 mm时,随调节刺激增加,4阶球差出现从大到小、从正值向负值的变化,但在瞳孔直径为3.0和2.0 mm时,4阶球差始终为正值.3阶水平方向三叶草像差在4.0、3.0、2.0 mm瞳孔直径下均表现出从负值向正值变化的规律.结论 不同瞳孔直径不同调节刺激下,正视眼各项单色高阶波阵面像差发生了不同规律和方向的变化.高阶像差在调节过程变化的意义和对不同注视距离视觉处理过程的作用有待于进一步研究,波阵面像差的研究将从单纯的消除向优化方向发展.     

Age-related changes in monochromatic wave aberrations of the human eye

PURPOSE. To investigate the relations between age and the optical aberrations of the whole eye. The eye's optical quality, as measured by the modulation transfer function (MTF), degrades with age, but the MTF does not provide a means to assess the contributions of individual aberrations, such as coma, spherical aberration, and other higher order aberrations to changes in optical quality. The method used in this study provides measures of individual aberrations and overall optical quality. METHODS. Wave aberrations in 38 subjects were measured psychophysically using a spatially resolved refractometer. Data were fit with Zernike polynomials up to the seventh order to provide estimates of 35 individual aberration terms. MTFs and root mean square (RMS) wavefront errors were calculated. Subjects ranged in age from 22.9 to 64.5 years, with spherical equivalent corrections ranging from +0.5 to -6.0 D. RESULTS. Overall RMS wavefront error (excluding tilts, astigmatism, and defocus) was significantly positively correlated with age (r = 0.33, P = 0.042). RMS error for the highest order aberrations measured (fifth through seventh order) showed a strong positive correlation with age (r = 0.57, P = 0.0002). Image quality, as quantified by the MTF, also degraded with age. CONCLUSIONS. Wave aberrations of the eye increase with age. This increase is consistent with the loss of contrast sensitivity with age observed by other investigators.     

Relationship between ocular wavefront aberrations and refractive error in Chinese school children

Background: The relationship between ocular wavefront aberrations and refractive error in children's eyes remains controversial. The purpose of this study is to re‐examine this relationship in Chinese school children under natural distance accommodation. Methods: Ocular wavefront aberrations were measured in 86 Chinese children with spherical equivalent refraction (SER) between +0.5 D and ‐6.0 D and astigmatism less than ‐1.00 D. Wavefront aberrations were calculated using an objective method based on the Hartmann‐Shack principle. Refractive error was obtained using a phoropter after cycloplegia. Subjects were categorised into three groups based on the mean SER: emmetropia (SER from ‐0.50 D to +0.50 D), mild myopia (SER greater than ‐0.50 D to ‐3.00 D) and moderate myopia (SER greater than ‐3.00 D to ‐6.00 D). Of the 86 participants, 22 were emmetropic, 43 were mildly myopic and 21 were moderately myopic. The root mean square (RMS) values of higher‐order aberrations, Zernike coefficients (third‐, fourth‐ and fifth‐order aberrations) and R_j (the ratio of third‐, fourth‐ or fifth‐order aberrations to total higher‐order aberrations) were compared across the three refractive groups. Results: No significant correlations were found between the RMS values of total higher‐order aberrations, third‐order aberrations, fourth‐order aberrations, fifth‐order aberrations, spherical aberration or coma and SER. No significant differences in the RMS values of total higher‐order aberrations or R_j were observed among the groups. The difference in fifth‐order aberrations was statistically significant among the groups (p = 0.022); no other differences in higher‐order aberration were found. Aside from C (3,1), no other differences were observed for Zernike coefficients. Conclusion: Ocular wavefront aberrations are similar among Chinese school children with different refractive errors under natural accommodation for a distance target. There is no evidence that myopes have a different amount of ocular higher‐order aberrations than emmetropes.     

近视青少年在阅读状态下调节反应和像差的研究

背景近距离工作时,视网膜的成像质量受调节、瞳孔和像差的共同影响;而近距离工作时视网膜成像的清晰度又被认为是青少年近视发生发展的可能诱因。因此,研究近视及正视青少年在阅读状态下的眼动参数和像差的差异性显得尤为重要。目的研究有初发性近视和进展性近视的青少年在阅读状态下的调节反应、瞳孔直径和像差的差异,从视网膜离焦诱导近视和像差诱导近视这两个假说探讨调节反应和像差与近视发生发展的相关机制。方法57例年龄12～16岁青少年受试者分为正视组16眼、初发性近视组20眼和进展性近视组21眼。嘱受试者阅读左眼前25effl处电脑显示屏上由快速序列视觉呈现方式软件所呈现的一篇中文短文,用SEIKO—WV500型自动验光仪测量调节反应,实时录像记录瞳孔直径,并用WASCA波前像差仪测量像差,对3组间的结果进行比较。结果各组受试者的调节反应和像差的个体差异均较大,在4D的调节刺激下,初发性近视组和进展性近视组的调节滞后值为（1．72±0．53）D,（1．74±0．44）D,高于正视组的（0．96±0．55）D,差异有统计学意义（t=4．25、t=4．47,P〈0．01）。初发性近视组和进展性近视组的调节滞后差异无统计学意义（t=0．18,P〉0．05）。调节刺激在0～4D时,所有受试者的瞳孔直径、全眼像差、高阶像差、球差和彗差均随着调节力的增加而显著减小（P〈0．01）,但在同一调节刺激下,不同屈光组之间受试者的瞳孔直径、全眼像差、高阶像差、球差和彗差的差异均无统计学意义（P〉0．05）。结论初发性近视和近视进展过程中在近距离阅读状态下存在较高的调节滞后,近距离阅读状态下对离焦的低模糊敏感性、较高的调节滞后及远视性离焦可能是近视发生、发展的促进因素。     

Spatially variant changes in lens power during ocular accommodation in a rhesus monkey eye

This study investigated the changes in ocular aberrations that occur over the entire lens equatorial diameter during accommodation in iridectomized rhesus monkey eyes to understand the nature of accommodative lenticular deformation. Accommodation was centrally stimulated to a range of different response amplitudes (0 D to approximately 11 D), and ocular aberrations were measured with a Shack-Hartmann wavefront sensor in both eyes of one previously iridectomized 10-year-old rhesus monkey. At the highest amplitude in the two eyes, aberrations were analyzed over entrance pupil diameters ranging from 3 to 8 mm in steps of 1 mm. Root mean square error of the total measured aberrations, excluding defocus, increased systematically with increasing accommodation from about 1 to 3.5 microns. Spherical aberration became systematically more negative, and vertical coma increased significantly in magnitude with accommodation. There was a strong accommodative change in power near the center of the lens and little change in power at the periphery. At the highest accommodative state, decreasing the analyzed entrance pupil diameter from 8 to 3 mm considerably reduced the wavefront error. The greater increase in optical power near the central region of the lens, combined with an accommodative pupillary miosis, would serve to maximize accommodative refractive change while maintaining acceptable image quality.     

儿童散光度数变化对波前像差的影响

目的 探讨儿童散光度数变化对波前像差的影响,进而评估儿童视觉质量.方法 收集就诊于大连医科大学附属第二医院眼科门诊的7 ～10岁儿童,散瞳3d,第4天行验光和OPD像差仪检查,选取符合入选标准的顺规散光儿童59例.患者依散光度大小分为低散光度组(1.00D≤散光度＜2.00D)、中散光度组(2.00 D≤散光度＜3.00 D)、高散光度组(3.00D≤散光度＜4.00 D).通过OPD检查获取波前像差、调制传递函数(modulation transfer function,MTF)和点扩散函数(point spreadfunction,PSF)等光学信息,进而分析全眼的总高阶像差、总彗差、总球差、总三叶草所对应的均方根值(root mean square,RMS)和MTF曲线对应的面积比值(area ratio,AR)及PSF曲线对应的斯特列尔比值(strehl ratio,SR).我们采用单因素方差分析比较三组间各高阶像差所对应的RMS值、AR值及SR值的差异.结果 4 mm瞳孔直径下,总高阶像差的均方根值、总彗差的均方根值及总三叶草的均方根值随着散光度的增加而增大,且三纽之间差别均有统计学意义(均为P＜ 0.05).总球差的均方根值随着散光度的增加而增大,但组间差别无统计学意义(P＞0.05).MTF曲线的AR值及PSF曲线的SR值都随着散光度增大而减小,且三组之间差别均有统计学意义(均为P＜0.05).结论 顺规散光儿童散光度的变化对高阶像差、MTF、PSF均有影响,顺规散光的大小主要对高阶像差的不对称成分产生影响.     

眼高阶像差评价分析

目的 :评价眼高阶像差的分布状况、影响因素及临床意义。方法 :利用基于Tscherning像差原理的Allegrettowaveanalyzer对 78例 ( 14 8眼 )要行LASIK治疗病人进行像差测量 ,其近视等效球镜为 -1 75D～ -10 0 0D ,年龄 19～ 3 6岁。比较眼在 4mm和 7mm瞳孔直径下眼高阶像差的分布及LASIK手术对眼高阶像差的影响。结果 :14 8眼近视者眼高阶像差 (即第三、四、五、六阶像差 )在 7mm瞳孔直径下的均方根值分别为 :RMS3 0 17± 0 0 7、RMS40 14± 0 14、RMS5 0 0 7± 0 0 5、RMS60 0 6± 0 0 6总的眼高阶像差RMSh为 0 2 6± 0 15 ,分别比 4mm瞳孔直径下增加97%、 194%、 110 %和 10 9% ,差别有统计学意义 (P <0 0 1) ;Lasik术后 1个月复查眼高阶像差均有不同程度增加 (从 5 3 %～88% ) ,其中第五阶像差增加最大 ,这会影响术后早期特别是低照明条件下的视力质量。结论 :在正常条件下 (瞳孔直径在 2 5～ 4mm) ,眼高阶像差处于一个低水平 ,随着瞳孔增大 (≥ 7mm )眼高阶像差尤其是球差、慧差成倍增加 ,屈光手术后也有类似情况 ,这将影响眼视觉质量     

掺钕钇铝石榴石激光后囊膜混浊切开对人工晶状体眼波前像差的影响

目的研究掺钕钇铝石榴石(Nd:YAG)激光后囊膜混浊切开对人工晶状体(IOL)眼波前像差的影响。方法对57例(68眼)白内障超声乳化吸除加IOL植入术后后囊膜混浊(PCO)患者行Nd:YAG激光后囊膜切开,激光前后应用NidekOPDScanⅠ角膜地形图/波前像差仪测量瞳孔直径为5.0mm时IOL眼的总像差、总高阶像差、球差、彗差和三叶草像差的均方根值(RMS),比较Nd:YAG激光前后波前像差的变化。Nd:YAG激光后囊膜切开采用环形切开向后翻转法,切开后囊膜瓣直径为5.0mm。结果激光术后最佳矫正视力较术前提高,差异有统计学意义(P<0.05)。激光术后总像差、总高阶像差、球差、彗差和三叶草像差的RMS分别为1.849±0.763、0.605±0.247、0.238±0.146、0.166±0.112及0.322±0.132,均较术前下降,差异有统计学意义(P<0.05)。结论 Nd:YAG激光后囊膜混浊切开直径5.0mm可以明显降低IOL眼的波前像差,改善视觉质量。     

近视散光患者眼球高阶像差的研究

目的了解国人近视散光患者眼球高阶像差的分布、瞳孔直径、近视、散光度数对高阶像差的影响。方法使用依据Tscherning原理设计的Allegretto Wave波前像差仪,对147只眼准分子激光原位角膜磨镶术(LASIK)前的近视散光情况进行检查,分别提取当瞳孔直径为4．0、4．5、5．0、5．0、5．5、6．0、6．5及7．0mm时高阶像差的均方根(RMS)值,根据近视和散光的度数高低分组对比研究分析。结果同一只眼内从3阶到6阶像差的RMS值呈递减趋势;同阶像差内最大值与最小值相差6．1至36．6倍;随着瞳孔的增大,高阶像差相应增加,尤其以3阶的彗差和4阶的球差增速快。当瞳孔小时近视度数只影响次级球差(第6级),随着瞳孔增大,近视度数既增加次级球差,也增加球差(第4级),当瞳孔直径≥5．0mm时,次级彗差(第五级)也增加,但在任何瞳孔直径下,近视度数对彗差无明显影响。散光度数对高阶像差的影响：当瞳孔直径≥6．5mm时,散光度数即使第3级彗差增加,也使第5阶的次级彗差增加,但在任何瞳孔直径下,散光度数对球差无明显影响。结论高阶像差在个体中存在较大差异,瞳孔直径、近视和散光程度对高阶像差有明显的影响。     

Optical quality and depth-of-field of eyes implanted with spherical and aspheric intraocular lenses

PURPOSE: To compare experimental optical performance in eyes implanted with spherical and aspheric intraocular lenses (IOLs). METHODS: Corneal, total, and internal aberrations were measured in 19 eyes implanted with spherical (n=9) and aspheric (n=10) IOLs. Corneal aberrations were estimated by virtual ray tracing on corneal elevation maps, and total aberrations were measured using a second-generation laser ray tracing system. Corneal and total wave aberrations were fit to a Zernike polynomial expansion. Internal aberrations were measured by subtracting corneal from total wave aberrations. Optical performance was evaluated in terms of root-mean-square (RMS) wavefront error and Strehl ratio (estimated from the modulation transfer function). Depth-of-field was obtained from through-focus Strehl estimates from each individual eye. RESULTS: Corneal aberrations increased after IOL implantation, particularly astigmatism and trefoil terms. Third and higher order RMS (and the corresponding Strehl ratio) were significantly better in eyes with aspheric IOLs than with spherical IOLs; however, this tendency was reversed when astigmatism was included. Spherical aberration was not significantly different in eyes with aspheric IOLs, whereas it was significantly positive in eyes with spherical IOLs. Third order aberrations were not significantly different across groups. Depth-of-field was significantly larger in eyes with spherical IOLs. Spherical IOLs showed better absolute optical quality in the presence of negative defocus >1.00 D. CONCLUSIONS: Our study shows a good degree of compensation of the corneal spherical aberration in eyes implanted with aspheric IOLs, as opposed to eyes implanted with spherical IOLs. Other sources of optical degradation, both with aspheric and spherical IOLs, are non-symmetric preoperative corneal aberrations, incision-induced aberrations, and third order internal aberrations. Although best corrected optical quality is significantly better with aspheric IOLs, tolerance to defocus tended to be lower.