Effect of aging on ocular light scatter and higher order aberrations

PURPOSE: To study the effect of aging on ocular light scatter and higher order aberrations in humans. METHODS: Seventy-six eyes of 76 normal subjects who had refractive errors but no ocular disease were studied. Their age ranged from 4 to 69 years (mean 34.8 +/- 5.8 yr). Both light scatter and total higher order aberrations were simultaneously and quantitatively measured by a Hartmann-Shack sensor for the central 4-mm-diameter pupil. Higher order aberrations were calculated from the Zernike polynomials up to the 4th order. The amount of light scatter was estimated by using the diameter of the point spread functions (PSFs) of the Hartmann images. A correction was made for the effect of the aberrations on the width of the images. Linear regression analysis was performed to investigate the effect of aging on light scatter and total higher order aberrations. RESULTS: A significant correlation was found between scatter and age (Spearman rank correlation coefficient, r = 0.501, P = .001). Also, the total higher order aberrations increased significantly with age (r = 0.323, P = .005). The total higher order aberration and scatter index were not statistically significantly correlated (r = 0.184, P = .112). CONCLUSIONS: These results indicate that scatter was better correlated with age than higher order aberrations.     

Diurnal fluctuation of higher order ocular aberrations: correlation with intraocular pressure and corneal thickness

PURPOSE: Optimal wavefront-guided refractive corneal laser surgery requires sufficiently exact data of optical higher order aberrations. We investigated whether these aberrations had a systematic during-the-day variation, studied the range of variation, and changes in intraocular pressure and central corneal thickness. METHODS: In 22 eyes of 22 young volunteers the optical aberrations of higher order were measured by means of a Tscherning-type ocular aberrometer three times during one day (7 AM, 12 noon, 4 PM). In addition, in 12 of these eyes the intraocular pressure and central corneal thickness were measured. The intraocular wavefront aberration was computed using Zernike polynomials up to the sixth order, and Zernike coefficients of third and fourth order were analyzed. RESULTS: Only the coefficient Z 2/4 (C13) showed a significant increase during the day by a mean 0.016 microm. A significant regression could be detected between changes of coefficients Z3/3, Z-2/4, Z0/4, Z4/4, and changes of intraocular pressure or central corneal thickness during the day. CONCLUSIONS: Due to the small values, the measured during-the-day changes of higher order aberrations had no direct practical consequences for the aberrometry-guided corneal laser surgery. Alterations of some Zernike coefficients during the day may be explained by the biomechanical behavior of the cornea.     

Toric设计角膜塑形镜矫正近视伴高度散光对角膜高阶像差的影响

目的 分析Toric设计角膜塑形镜矫正近视伴高度散光后角膜高阶像差的变化.设计回顾性病例系列.研究对象2018年5月至2019年2月内江市第一人民医院配戴Toric设计角膜塑形镜患者35例(67眼),近视屈光度-1.00～-4.00 D,散光-1.50～-3.00 D.方法 测量戴镜前,戴镜后1、3、6、12个月的裸眼...     

Total ocular, anterior corneal and lenticular higher order aberrations in hyperopic, myopic and emmetropic eyes

Total ocular higher order aberrations and corneal topography of myopic, emmetropic and hyperopic eyes of 675 adolescents (16.9 ± 0.7 years) were measured after cycloplegia using COAS aberrometer and Medmont videokeratoscope. Corneal higher order aberrations were computed from the corneal topography maps and lenticular (internal) higher order aberrations derived by subtraction of corneal aberrations from total ocular aberrations. Aberrations were measured for a pupil diameter of 5 mm. Multivariate analysis of variance followed by multiple regression analysis found significant difference in the fourth order aberrations (SA RMS, primary spherical aberration coefficient) between the refractive error groups. Hyperopic eyes (+0.083 ± 0.05 μm) had more positive total ocular primary spherical aberration compared to emmetropic (+0.036 ± 0.04 μm) and myopic eyes (low myopia = +0.038 ± 0.05 μm, moderate myopia = +0.026 ± 0.06 μm) (p < 0.05). No difference was observed for the anterior corneal spherical aberration. Significantly less negative lenticular spherical aberration was observed for the hyperopic eyes (−0.038 ± 0.05 μm) than myopic (low myopia = −0.088 ± 0.04 μm, moderate myopia = −0.095 ± 0.05 μm) and emmetropic eyes (−0.081 ± 0.04 μm) (p < 0.05). These findings suggest the existence of differences in the characteristics of the crystalline lens (asphericity, curvature and gradient refractive index) of hyperopic eyes versus other eyes.     

近视眼患者角膜高阶像差分布及LASIK和波前像差引导的优化LASIK术后高阶像差变化的研究

目的比较常规准分子激光原位角膜磨镶术（laserin situ keratomileusis,LASIK）和角膜波前像差引导的优化屈光角膜切削术（optimized refractive keratomy,ORK）后近视眼患者视力及角膜前表面高阶像差的变化,探讨角膜波前像差引导的优化准分子激光原位角膜磨镶术（ORK-LASIK）的安全性和有效性。方法选取拟做LASIK手术的近视眼患者396例733眼,按球镜屈光度分成低度（≤-3.00D）、中度（-3.00～-6.00D）和高度（-6.00～-12.00D）3组,每组柱镜度数均小于-2.50D,各组再随机分成2组,一组行常规LASIK手术,另一组行ORK-LASIK。手术切削区直径为6.0～7.0mm。角膜波前像差分析为6mm瞳孔直径。术后随访6个月,检查裸眼视力及角膜地形图并进行波前像差分析。结果成人近视眼角膜前表面波前像差在6mm瞳孔直径以3阶和4阶为主,占90%,在3阶和4阶中又以彗差和球差为主,分别占角膜全部像差的27.7%和28.4%;球差和球镜度数呈负相关（r=-0.501,P〈0.05）,其他高阶像差和球镜度数无关。但在-6.00D以上的近视眼中,彗差和次级彗差均和球镜度数有关（F=8.808,7.123,P〈0.04,0.01）。角膜前表面各高阶像差均和年龄及性别无关。LASIK和ORK-LASIK2组比较,术后6个月时,低度和高度组2组的裸眼视力均达到术前矫正视力,差异无统计学意义（P〉0.05）;在中度组,ORK-LASIK组视力明显好于LASIK组,2组差异有统计学意义（P〈0.05）。术后6个月时,角膜前表面的球差、彗差和总高阶像差均较术前增加,和术前比较差异有统计学意义（P〈0.05）。在低度组,ORK-LASIK组和LASIK组比较角膜彗差和球差2组间差异无统计学意义（P〉0.05）;中、高度组ORK-LASIK组角膜彗差和球差较LASIK组明显下降,差异有统计学意义（P〈0.05）。结论角膜波前像差引导的ORK-LASIK手术能有效地矫正近视和散光,提高中度近视患者的视力,降低中、高度组术后彗差和球差,手术效果稳定、安全。     

Effect of incision types for Artisan phakic intraocular lens implantation on ocular higher order aberrations

AIM: To evaluate the effect of incision types for Artisan phakic intraocular lens (PIOL) implantation on ocular higher-order aberrations (HOAs). METHODS: A retrospective review was conducted of the patients who had undergone Artisan PIOL implantation for the correction of myopia and followed up for at least 6mo. Patients are classified into 2 groups considering the incision type: cornea group with patients undergone clear corneal incision; sclera group with patients undergone sclera tunnel incision. All patients with postoperative astigmatism of under 1 diopter (D) were included to minimize the effect of residual astigmatism on postoperative HOAs. Visual acuity, special equivalents, astigmatism, predictability (±1 D from target refraction), HOAs (coma, trefoil, spherical aberration), and corneal endothelial counts were analyzed preoperatively and 6mo postoperatively. RESULTS: At the postoperative 6mo, all patients of both groups achieved uncorrected visual acuity of 16/20 or better, and significantly decreased the spherical equivalents compared with preoperative values. The predictability of refractive correction was 96% in the former, and 94% in the latter. Unlike the sclera group, preoperative astigmatism decreased significantly in cornea group at postoperative 6mo. The HOAs increased significantly at postoperative 6mo compared to the preoperative values in both groups, and the root mean square (RMS) total and trefoil wavefront aberration of cornea group were significantly higher than those of sclera group. CONCLUSION: Although corneal incision significantly reduces preexisting astigmatism, the postoperative 6mo of total RMS and trefoil aberration change may deteriorate the visual quality after Artisan PIOL implantation.     

近视散光患者角膜形态对高阶像差的影响

目的 探讨近视散光患者高阶像差的分布特点及角膜形态对其的影响.方法 用wavescan wavefront system波前像差仪对LASIK术前281例（434眼）近视散光患者进行客观测量,用TMS-4角膜地形图仪获得角膜表面规则指数（surface regularity index,SRI）、角膜表面不对称指数（surface asymmetry index,SAI）以及角膜表面形态.对屈光度、SRI和SAI与高阶像差作相关分析,将患者分别按角膜形态分为5组,对各组间的高阶像差的均方根值（root mean square,RMS）作秩和检验.结果 6.0 mm瞳孔直径下的总高阶像差（root mean square of higher order aberrations,RMSh）的均方根值为（0.286±0.098）μm,从3阶至6阶大致呈递减趋势,其中以3阶彗差、三叶草和4阶球差的均数最大.屈光力和SRI与RMSh没有显著的相关性,SAI与RMSh呈正相关,Pearson相关系数为0.161,P值为0.001.SAI值对高阶像差的影响较SRI值大,尤其是SRI值较低的患者,RMSh值随SAI的增高而增大,主要表现为3阶彗差和4阶球差的增大.角膜形态为不规则形和不对称领结形时高阶像差最大,主要表现为三叶草和3阶彗差的增大.结论 6.0 mm瞳孔直径时,最主要的高阶像差是3阶彗差、三叶草和4阶球差.角膜形态为不规则形和不对称领结形时高阶像差最大.SAI对高阶像差的影响比SRI大.     

SMILE与Trans-PRK手术矫正近视对角膜前表面像差的影响

目的：观察飞秒激光小切口角膜基质透镜取出术(SMILE)和经上皮准分子激光屈光性角膜切削术(Trans-PRK)矫正近视对角膜前表面三阶水平彗差、三阶垂直彗差、四阶球差和总高阶像差的影响。

方法：前瞻性非随机对照研究。收集2016-12/2017-02在乐山市眼科中心行SMILE手术及Trans-PRK手术矫正近视患者各20例40眼,分别于术前及术后1、3mo用Pentacam角膜地形图仪进行角膜像差检查。采用重复测量方差分析对角膜前表面三阶水平彗差、三阶垂直彗差、四阶球差和总高阶像差均方根进行统计分析。

结果：术后1、 3mo SMILE组和Trans-PRK组患者裸眼视力均达到或超过术前最佳矫正视力。术前两组患者各项角膜像差比较差异无统计学意义(P>0.05),术后两组患者角膜像差较术前均增高,差异有统计学意义(P<0.05),两组患者角膜像差在术后1、 3mo之间比较差异无统计学意义(P>0.05),术后各时间点两组患者水平彗差、垂直彗差之间比较差异无统计学意义(P>0.05),SMILE组患者术后四阶球差及总高阶像差均方根低于Trans-PRK组,差异有统计学意义(P<0.05)。

结论：SMILE与Trans-PRK手术矫正近视术后角膜像差均增高,两种手术方式对角膜三阶水平彗差和垂直彗差影响相似,SMILE手术对四阶球差及总高阶像差的影响较Trans-PRK手术更小。     

SMILE术后角膜前表面非球面性与角膜高阶像差的关系

目的探讨SMILE术后角膜前表面非球面性与角膜高阶像差变化特点及其相关性。方法前瞻性研究。随机选取自愿行SMILE手术的屈光不正患者41例,均选右眼为研究眼,于手术前及手术后3个月分别测量患者角膜前表面6、7、8、9mm直径范同的非球面系数Q值,并测量角膜总高阶像差（HOA）、球差（Z4^0）、次级球差（Z6^0）、垂直彗差（Z3^-1）、水平彗差（Z3^1）、水平三叶草（Z3^-3）、倾斜三叶卓（Z3^3）等高阶像差。采用配对t检验和Pearson相关进行数据分析。结果SMILE手术后角膜前表面6、7、8、9mm直径范围Q值均Fh负值转变为正值（t=-23．558、-26．661、-28．366、-28．788,P〈0．01）。角膜HOA、Z4^0、Z6^0、Z3^-1、Z3^1数值均增大（t=-11．815、-11．813、-16．209、6．470、4．835,P〈0．01）,而Z3^-3、Z3^3与术前比较差异无统计学意义（t=0．278、-1．064,P〉0．05）。术前角膜HOA、Z4^0、Z3^-1与Q值有-定的相关性（P〈0．05）,SMILE手术前后角膜HOA、Z4^0差值与角膜前表面各直径范同Q值差值均呈正相关关系（HOA：r=0．554、0．480、0．416、0．352,P〈0．05;Z40：r=0．671、0．577、0．495、0．395,P〈0．05）：Z3^-1差值与6、7mm直径范同Q值差值呈正相关（r=0．377、0．342,P〈0．05）;Z3^-1差值与6、7、8mm直径范同Q值差倩呈止相关（r=0．436、0．385、0．316,P〈0．05）;Z6^0、Z3^-3、Z3^3差值与各直径范同Q值差值均无相关性。透镜直径与SMILE手术前后Q值差值无相关性;与角膜HOA、Z4^0差值呈负相关（r=-0．315．-0．393,P〈0．05）;与角膜Z6^0、Z3^-1、Z3^-1、Z3^-1、Z3^3差值均无相关性（P〉O．05）。结论SMILE手术后角膜前表面O值由负值转变为止佰;角膜高阶像差增大;透镜直径越大,角膜HOA、Z4^0变化越小。角膜前表面Q值与角膜HOA、Z4^0、Z3^-1、Z3^1变化量均有正相关关系,其中与Z4^0相关程度最强?     

LASIK手术前后屈光状态和角膜形态对高阶像差的影响

目的 分析近视散光患者行准分子激光原位角膜磨镶术(LASIK)手术前后屈光状态和角膜形态对高阶像差的影响.方法 在LASIK术前和术后6个月,分别对患者69例108眼进行角膜地形图和波前像差检查,屈光矫正范围(-1.25～-9.00)D,切削直径为6.0 mm或6.5 mm.结果 LASIK手术前后在6.0 mm瞳孔直径下最主要的高阶像差是3阶彗差、4阶球差和三叶草散光,术后总高阶像差的均方根(RMSh)增加1.82倍.术后RMSh变化与近视度的矫正量呈正相关,主要表现为3阶彗差和4阶球差的变化.术后角膜表面不对称指数(SAI)显著增加,RMSh的变化与其增加量呈正相关,特别是3阶彗差.角膜形态术前为不规则型及术后为半环型和中央岛型时SAI增大,高阶像差增大.结论 LASIK手术前后的主要高阶像差均为3阶彗差和4阶球差.术后总高阶像差增大,主要表现为慧差增大,可能为角膜表面的不对称性增大引起.     

Age-related changes in ocular and corneal aberrations

PURPOSE: To compare the ocular and corneal higher-order aberrations (HA) in eyes of different ages. DESIGN: Observational cross-sectional study. METHODS: Sixty-six eyes of 66 normal subjects (age range 4-69 years; average 37.4 +/- 15.4 years) were examined. Wavefront aberrations of the whole eye (ocular) and cornea were measured for the central 4 mm using a Hartmann-Shack aberrometer. RESULTS: Ocular Coma-like aberration (r = 0.270, P =.029), Spherical-like aberration (r = 0.531, P =.001), and total HA(r = 0.431, P =.001) were significantly correlated with age, whereas the corneal aberrations were not significantly correlated. The ocular total HA aberrations increased significantly after age 50 years. CONCLUSIONS: After 50 years of age, ocular aberrations increased abruptly due to the increase of lenticular HA. Customized ablation should be carefully considered, especially in eyes of presbyopic age.     

Peripheral refraction and higher order aberrations

Peripheral image quality influences several aspects of human vision. Apart from off-axis visual functions, the manipulation of peripheral optical errors is widely used in myopia control interventions. This, together with recent technological advancements enabling the measurement of peripheral errors, has inspired many studies concerning off-axis optical aberrations. However, direct comparison between these studies is often not straightforward. To enable between-study comparisons and to summarise the current state of knowledge, this review presents population data analysed using a consistent approach from 16 studies on peripheral ocular optical quality (in total over 2,400 eyes). The presented data include refractive errors and higher order monochromatic aberrations expressed as Zernike co-efficients (reported in a subset of the studies) over the horizontal visual field. Additionally, modulation transfer functions, describing the monochromatic image quality, are calculated using individual wavefront data from three studies. The analysed data show that optical errors increase with increasing eccentricity as expected from theoretical modelling. Compared to emmetropes, myopes tend to have more hypermetropic relative peripheral refraction over the horizontal field and worse image quality in the near-periphery of the nasal visual field. The modulation transfer functions depend considerably on pupil shape (for angles larger than 30°) and to some extent, the number of Zernike terms included. Moreover, modulation transfer functions calculated from the average Zernike co-efficients of a cohort are artificially inflated compared to the average of individual modulation transfer functions from the same cohort. The data collated in this review are important for the design of ocular corrections and the development and assessment of optical eye models.     

Advanced corneal surface ablation efficacy in myopia: changes in higher order aberrations

Objective: To evaluate the change of ocular and corneal higher order aberrations (HOAs) after wavefront-guided advanced surface ablation (WF-ASA) for myopia using 4 different epithelial management techniques (AA-PRK, LASEK, Epi-PRK, and Epi-LASIK).Design: Retrospective single centre excimer database analysis.Participants: Two hundred and forty eyes equally divided between the 4 WF-ASA techniques, matched for mean and range of required spherical correction.Methods: Ocular wavefront aberrations were measured using the wavescan aberrometer and corneal aberrations were obtained from corneal topography elevation maps and calculated by ray-tracing. All data were collected preoperatively and 3 months following treatment. The aberrations were described as Zernike polynomials, and analysis focused on total HOAs and spherical aberration (SA).Results: Three months postoperatively, there was a statistically significant surgically induced increase in total HOAs and SA both for ocular and corneal analysis (p < 0.001). There was no statistically significant difference in the induced ocular SA and HOAs between the groups, but the differences in induced corneal SA and HOAs were significant (p = 0.010). Ocular changes in SA were weakly correlated to preoperative SA (−0.30, p < 0.001) but strongly correlated to applied spherical correction (−0.68, p < 0.001). Surgically induced corneal SA was weakly correlated to preoperative corneal SA (−0.34, p < 0.001) and applied spherical correction (−0.46, p < 0.001).Conclusions: Three months postoperatively, all procedures resulted in an increase in ocular and corneal HOAs and SA. Induced aberrations were most strongly correlated to the applied spherical power correction. Modifying the existing ablation pattern to compensate for induced HOAs might improve the outcome.     

小梁切除术对角膜曲率及眼轴的影响

目的观察并分析小梁切除术后角膜曲率和眼轴长度的改变及术中丝裂霉素C（MMC）的应用对其影响。方法青光眼小梁切除术20例31眼,其中7眼术中应用MMC,分别测定术前、术后1个月及3个月的角膜曲率、眼轴长度,采用SPSS13．0统计软件对资料进行分析。结果小梁切除术后1个月及3个月,循规散光较术前增加。术中应用MMC者术后1个月,循规散光较未用MMC者增加（P〈0．05）,但术后3个月循规散光恢复到术前状态（P〉0．05）。小梁切除术和MMC的应用对术后3个月的眼轴长度无明显影响,手术前后比较差异无统计学意义（P〉0．05）。结论小梁切除术后主要发生循规性散光。MMC会引起短期的循规性散光增加,但远期（3个月）不会引起角膜曲率的变化。小梁切除术和MMC的应用不会引起眼轴长度的变化。     

Postblink changes in total and corneal ocular aberrations

OBJECTIVE: The purpose of this study was to determine objectively the changes in optical aberrations induced by the progressive tear film irregularity after a blink and their effects on retinal image quality. DESIGN: Prospective, consecutive, nonrandomized comparative trial (self-controlled). PARTICIPANTS: Twenty healthy subjects. MAIN OUTCOME MEASURES: Corneal and total ocular aberrations were determined in 20 subjects at various time intervals (approximately 0, 10, and 20 seconds) after a blink. Corneal and total aberrations were measured with an Orbscan II topographer (Orbtek Inc, Salt Lake City, UT) and a Zywave aberrometer (Bausch & Lomb, Irvine, CA), respectively. All data were decomposed using Zernike polynomials to yield the root mean square wavefront deviations, in micrometers (microm), for different pupil diameters (3.5, 4.5, 5.5, and 6.5 mm). A merit function (Mf), defined as the volume under the 2-dimensional modulation transfer function as computed from the total wavefront error, was taken as the image quality metric. RESULTS: Both corneal and total aberrations (third order and higher) showed a statistically significant increase with time after the blink for all pupil diameters except 3.5 mm. The magnitude of the increase was greater at larger pupil diameters. For a 6.5-mm pupil, the aberrations increased on average by a factor of 2.5 (total) and 2.5 (corneal). Increases in total aberration were related closely to increases in corneal aberration (P<0.0001). For a 6.5-mm pupil, after 20 seconds, the reduction in optical quality (Mf) among the subjects studied was 21+/-8%. CONCLUSIONS: After a blink, the gradual increase in optical aberration associated with the increasingly irregular tear film may cause a progressive reduction in the optical quality of the eye. These changes in aberration with time may partly limit the improvements in visual performance that are achievable by customized corneal ablation.     

两种角膜缘切口白内障超声乳化吸除联合人工晶状体植入术后角膜前后表面高阶像差的影响

目的：探讨2．2 mm、3．0 mm两种角膜缘切口白内障超声乳化吸出术联合人工晶状体植入术后角膜前后高阶像差的变化情况。方法回顾性分析我院72例（130只眼）白内障患者根据治疗方法不同分为A组（2．2 mm切口）和B组（3．0 mm切口）各36例患者,分别于术前、术后3个月测量两组患者的角膜前后表面的高阶像差[总的高阶像差（ tHOAs）、慧差（ Coma）、初级球差（ SA）]的变化情况。结果 A组、B组患者手术前、手术后3个月组内、组间角膜前表面的tHOAs、Coma、SA测定值差异均无统计学意义（ P ＞0．05）;A组患者术后3个月的角膜后表面SA值较术前显著的提高（ P ＜0．05）,B组患者术后3个月的角膜后表面tHOAs值较术前显著提高（ P ＜0.05）;A组患者术后3个月角膜后表面的SA值大于B组（ P ＜0．05）,B组患者术后3个月的角膜后表面tHOAs值显著高于A组（ P ＜0．05）。结论2．2 mm、3．0 mm两种角膜缘切口白内障超声乳化吸出术联合人工晶状体植入术后角膜前表面高阶像差变化不显著,角膜后表面的高阶像差指标会受到一定程度的影响,这可能与手术质量具有一定的关系。