Far and near visual acuity with multifocal intraocular lenses in an optomechanical eye model with imaging capability

PURPOSE: To compare the quantitative and qualitative visual performances of different multifocal intraocular lenses (IOLs) in an experimental model of the human eye. SETTING: University Hospital San Raffaele, Milan, Italy. METHODS: Five multifocal IOLs and 1 monofocal IOL were implanted in an optomechanical eye model with imaging capability. The comparative optical characterization of the imaging performance included aberrometry, simulated visual acuity testing at variable contrast for far and near distance, glare tests, and image records of optotype charts. RESULTS: The maximum recorded far visual acuity for the monofocal IOL was between 20/12.5 and 20/16; the multifocal IOLs decreased visual acuity by 1 to 2 lines. The difference tended to increase at reduced contrast. Full-contrast near visual acuity with multifocal IOLs ranged between 20/63 and 20/25; the near distance performance of the monofocal IOL without an additional correcting lens was worse by 1 to 3 lines of acuity with large pupils but was comparable with small pupils. Multifocal IOLs of different designs showed marked differences as a function of contrast, which tended to balance between far and near behaviors. CONCLUSIONS: Multifocal IOLs of different optical designs were well characterized and distinguished by simulated contrast acuity testing in an experimental eye model, allowing quantitative comparison. Their overall visual performance, averaged over contrast and distance, was not superior to the performance of a monofocal IOL without an additional correcting lens.     

1CU可调节人工晶状体眼的近期视觉质量评价

目的评价1CU可调节后房型人工晶状体（IOL）眼的视觉质量,并与非球面单焦点IOL眼进行比较。设计非随机对照试验。研究对象老年性白内障患者118例（118眼）。方法白内障超声乳化吸除术时植入1CU可调节IOL（1CU组）和非球面IOL（Tecnis ZA9003组）各为59例59眼。术后3个月时检查裸眼及矫正远、近视力,最佳矫正远视力下的近视力,波前像差,调制传递函数,40、63、100cm处对比敏感度,拟调节力,并比较脱近用镜率。主要指标视力、波前像差、调制传递函数值、对比敏感度、拟调节力、脱近用镜率。结果术后3个月1CU组的裸眼近视力（1．06±0．24）和最佳矫正远视力下的近视力（1．02±0．13）优于TecnisZA9003组（分别为0．43±0．14、0．43±0．11）（江8．85,P=0．00;t=13．05,P=0．00）。调节幅度1CU组为（2．58±0．37）D,大于非球面IOL组的（1．46±0．25）D（t=14．33,P=0．00）。1CU组3mm、5mm瞳孔下的球差（0．34±0．06、0．36±0．06）和总像差（0．47±0．14、0．49±0．14）均大于Tecnis ZA9003组（分别为0．06±0．06、0．07±0．04,0．30±0．07、0．30±0．58）（3mm瞳孔下t=18．48,P=0．00;t=5．70,P-0．00。5mm瞳孔下f=19．98,P=0．00;t=6．70,P=0．oo）。在40、63 cm1CU组视锐度得分（VAS）分值高于Tecnis ZA9003组（t=3．64,P=0．00;t=2．74,P=0．00;t=2．65,P=0．00;t=2．44,P=0．01）。脱近用镜率1CU组（85％）优于Tecnis ZA9003组（25％）（χ^2=41．95,P=0．00）。结论虽然1CU可调节后房型IOL对比敏感度较非球面单焦点IOL有损失,但可获得良好远、中、近视力,适合于迫切要求脱镜的患者。（眼科,2009,18：91-95）     

基于模型眼的球面人工晶状体单色像差分析

目的运用基于Hartmann-Shack原理的模型眼来评价球面人工晶状体（IOL）单色像差。方法前瞻性研究。本研究分为2个部分。①选取SA60AT（美国Alcon公司）系列IOL 5片,屈光度分别为+10、+15、+20、+25、+30 D;②选取IOL 3片,屈光度均为+20 D,分别为SA60AT、Akreos Adapt（美国博士伦公司）、AR40e（美国AMO公司）。搭建模型眼光路,将待测IOL置于光路中,以电子耦合设备（CCD）图像传感器接受像点,测出在436、486、525、546、589、660、710 nm不同波长下的像点图,经Matlab软件进行处理,采用双因素Pearson相关分析及单因素方差分析评价IOL的单色像差。结果第一部分：SA60AT系列IOL的球差（Z12,r=0.599,P<0.05）、垂直彗差（Z7,r=0.817,P<0.05）、水平彗差（Z8,r=0.488,P<0.05）与屈光度呈正相关,总高阶像差均方根值（RMSh）与屈光度不相关（r=0.007,P>0.05）;波长与球差（r=-0.213,P>0.05）、垂直彗差（r=-0.074,P>0.05）、水平彗差（r=0.021,P>0.05）及RMSh（r=-0.322,P>0.05）均不相关。第二部分：3种IOL的球差（F=74.637,P<0.05）、水平彗差（F=6.719,P<0.05）及RMSh（F=11.768,P<0.05）差异有统计学意义,垂直彗差差异无统计学意义（F=1.295,P>0.05）,AR40e的球差、水平彗差及RMSh相对最小;波长与各IOL的球差（r=0.007,P>0.05）、垂直彗差（r=-0.312,P>0.05）、水平彗差（r=-0.238,P>0.05）及RMSh（r=0.246,P>0.05）均不相关。结论利用Hartmann-Shack原理设计的模型眼可以便捷地检测IOL的单色像差,为临床上IOL的选择及其光学设计的改进提供了参考依据。     

Possibilities of intracapsular implantation of intraocular lenses in eye injuries

The authors analyze the results of 63 surgeries for implantation of intraocular lenses, V. N. Alexeyev's design, in patients with traumatic cataracts and other injuries after perforating and contusion injuries. The results evidence a high efficacy of intracapsular implantation. Vision acuity with correction has improved in 36 eyes to make up 0.5 and more diopters. In the rest cases (27 eyes) vision acuity with correction has made up 0.1-0.4. The implantation was simple and the course of the postoperative period smooth in the patients with membranous and semiresolved cataracts, with primary and secondary glaucoma, and implantation into the posterior chamber.     

非球面人工晶状体在个体化人眼模型中成像质量的研究

目的 根据不同患者眼部解剖参数建立个体化眼模型,研究植入不同设计的人工晶状体（IOL）后的光学表现.方法 计算机数字模拟实验.采用Pentacam眼前节分析系统、IOL Master采集白内障摘除联合IOL植入术后人眼结构数据,应用ZEMAX光学设计软件建立个体化眼模型,分别模拟植入不同设计的3种非球面IOL（SofPort AO、Tecnis Z9000、FY60AD）和1种球面IOL（YA60BBR）,计算这些IOL眼3 mm、4 mm、5 mm瞳孔下的调制传递函数（MTF）和对比敏感度函数（CSF）曲线.结果 随瞳孔直径增加,全眼MTF、CSF曲线高度下降;3 mm瞳孔下,个体化眼模型中3种非球面IOL的MTF和CSF曲线与球面IOL接近;5 mm瞳孔下,个体化眼模型植入4种IOL后MTF和CSF曲线差异明显,不同解剖结构参数个体获得最佳MTF和CSF曲线的IOL种类不同,在空间频率较高时更加明显.结论 根据人眼解剖参数建立个体化眼模型可以模拟该个体眼睛光学系统的光学质量.不同解剖结构的人眼光学系统获得最佳视觉质量所需的IOL种类不同.     

Astigmatic power calculations for intraocular lenses in the phakic and aphakic eye

PURPOSE: To develop sets of equations employed in the power calculations for toric intraocular lenses (IOLs) in phakic or aphakic astigmatic eyes. METHODS: Mathematical operations to convert from standard toric parameters of sphere, cylinder, and axis to astigmatic decomposition components, and vice versa, are presented. These operations are used to derive equations to calculate the ideal toric IOL power for a phakic or aphakic astigmatic eye, predict the postoperative spectacle correction for a selected toric IOL with power other than the ideal power, and back calculate a parameter to be used to optimize predictability of the calculations based on clinical data. RESULTS: Two numerical examples are provided to show how the equations are used with clinical data. CONCLUSION: The equations developed provide a method to perform toric IOL power calculations and supporting operations of predicted postoperative spectacle refraction and optimization of prediction error for phakic and aphakic eyes with astigmatism.     

Heparin surface modified intraocular lenses implanted in the monkey eye

The biocompatibility of heparin surface modified poly(methyl methacrylate) intraocular lenses (IOLs) was evaluated in two experiments following implantation in the anterior and posterior eye chambers of adult cynomolgus monkeys. Throughout the study, large inflammatory cells and prominent pigment deposits were seen on the unmodified lenses, whereas the heparin surface modified IOLs remained almost free of precipitates. Similarly, fewer posterior synechias were observed in eyes implanted with surface modified IOLs in the posterior chamber than in eyes implanted with control lenses. Histopathological examination of enucleated eyes confirmed the clinical findings. These experiments strongly support the idea that surface modification with heparin is a useful way to reduce clinical complications following cataract surgery with IOL implantation.     

Prospective visual evaluation of apodized diffractive intraocular lenses

PURPOSE: To evaluate distance, intermediate, and near visual performance in patients who had multifocal apodized diffractive intraocular lens (IOL) implantation. SETTING: Fernández-Vega Ophthalmological Institute, Oviedo, Spain. METHODS: The best corrected distance visual acuity, best distance-corrected near visual acuity, intermediate visual acuity, distance contrast sensitivity under photopic and mesopic conditions, and patient satisfaction were measured in 325 patients and 335 patients who had bilateral implantation of the model SA60D3 IOL (AcrySof ReSTOR, Alcon) and model SN60D3 IOL (AcrySof Natural ReSTOR), respectively. RESULTS: At the 6-month postoperative visit, binocular best corrected distance acuity with the ReSTOR IOL and the Natural ReSTOR IOL was 0.034 logMAR+/-0.004 (SD) and 0.019+/-0.020 logMAR, respectively (approximately 20/20). Binocular best distance-corrected near acuity was 0.011+/-0.012 logMAR and 0.035+/-0.013 logMAR, respectively (approximately 20/20). Intermediate visual acuity with both IOL models worsened significantly as a function of the distance of the test (P<.01). Photopic contrast sensitivity was within the standard normal range with both IOLs. Under mesopic conditions, contrast sensitivity with both IOLs was comparable to that with monofocal IOLs and lower, particularly at higher spatial frequencies, than under photopic conditions. No statistically significant differences in visual acuity or photopic and mesopic contrast sensitivity were found between the 2 IOL models (P>.1). A patient satisfaction questionnaire showed that both IOLs performed well and were comparable in satisfaction regarding distance, intermediate, and near activities under different lighting conditions. CONCLUSIONS: The AcrySof ReSTOR IOL and AcrySof Natural ReSTOR IOL provided good visual performance at distance and near under photopic and mesopic conditions. Intermediate vision with both models was reduced compared with distance and near vision.     

Implantation of retropupillary intraocular lenses in post-traumatic conditions of the eye

The investigation comprises the results of post-traumatic artephakias. In the course of 15 months the authors treated 15 patients with traumatic cataract after previous perforating or blunt eye injuries. In 12 patients after extracapsular extraction a retropupillary IOL was implanted. In three patients implantation was not performed. Retropupillary pseudophakia is the optimal correction of aphakia even in patients with previous serious eye injuries. A higher incidence of postoperative complications may be expected.     

Calculations for intraocular lenses]

The authors deal with the postoperative dioptric deviation from the calculated optic potency of the emetropic intraocular lens, using formulae SRK II, SRK/T and Holladay's formula. Within the range +/- 1.5 D the deviation varied in 84% of the operated eyes where the intraocular lens was assessed according to formula SRK II; in 76% when formula SRK/T was used and in 74% when Holladay's formula was used. The authors give also an account of possible sources of errors during measurement, calculation and evaluation of results.     

Refractive errors induced by displacement of intraocular lenses within the pseudophakic eye

Simple methods were developed to estimate refractive errors when intraocular lenses are not fitted optimally within pseudophakic eyes. The accuracy of these methods was determined by comparing results obtained with them to results obtained by raytracing through a model eye. Accuracy was good for longitudinal displacement and tilting, and reasonable for transverse displacement. Refractive errors are related linearly to the magnitude of the longitudinal displacement, and are related to the square of the magnitude of tilt or transverse displacement. The refractive error upon transverse displacement is quadratically dependent upon lens shape.     

Optical performance of monofocal and multifocal intraocular lenses in the human eye

PURPOSE: To study the optical performance of intraocular lenses (IOLs) in the human eye to ascertain how multifocality affects the optical performance of refractive and diffractive technologies and the relationship to pupil size. SETTING: Vissum-Instituto de Oftalmológico de Alicante, Alicante, Spain. METHODS: Ten eyes each received the monofocal AcrySof MA60 IOL (Alcon) or 1 of the following multifocal pupil-dependent IOLs: diffractive AcrySof ReSTOR (Alcon) or refractive ReZoom (Advanced Medical Optics). The intraocular optical quality in vivo with 3.0 mm and 5.0 mm pupils was characterized by comparing the means of the difference between the total and corneal optical aberrations 3 months postoperatively. The main outcomes measures were total, higher-order, spherical, and coma aberrations (root-mean-square values); modulation transfer function values; point-spread function; and the Strehl ratio. RESULTS: The ReZoom group had higher in vivo intraocular aberrations than the AcrySof ReSTOR and AcrySof MA60 groups (P = .022). The difference in spherical aberration between the AcrySof ReSTOR and ReZoom groups was statistically significant with 5.0 mm pupils (P = .003) and 3.0 mm pupils (P = .001). The AcrySof ReSTOR group had statistically significant lower coma aberration values with a 5.0 mm pupil (P = .012); there were no differences between IOLs with a 3.0 mm pupil (P = .185). CONCLUSIONS: Multifocal refractive IOLs resulted in higher intraocular aberrations. The hybrid refractive-diffractive IOL was the least affected by pupil diameter in terms of intraocular aberrations and showed significantly less increase in optical aberrations when the pupil was enlarged.     

An optical model to describe image contrast with bifocal intraocular lenses

We attempted to quantify the decrease in contrast associated with the concentric-style bifocal intraocular lens by using a model eye and bifocal intraocular lens, with a model unifocal intraocular lens as a control. When imaging near objects, pupils smaller than 2.5 mm produced image contrast of 100% of the control; larger pupils degraded contrast to 25% for a 6-mm pupil. For distant objects, pupils smaller than 2.5 mm produced image contrast of 70% to 95% because of the pinhole effect; larger pupils engaged the distance portion of the intraocular lens and maintain 80% contrast on average. Thus, the bifocal intraocular lens produced image contrast greater than 70% in all situations tested, except when imaging near objects with a pupil larger than 3.5 mm. The data suggest that image contrast is highly dependent on pupil size and object distance.