The binocular intraocular lens power difference in eyes with different axial lengths

AIM:To investigate the binocular intraocular lens(IOL)power difference in eyes with short,normal,and long axial lengths(AL)using Lenstar LS 900 optical biometry.METHODS:A total of 716(1432 eyes)participants were included.The groups were categorized into short(group A:AL<22 mm),normal(group B:22 mm≤AL≤25 mm),and long AL groups(group C:AL>25 mm).The central corneal thickness(CCT),anterior chamber depth(ACD),lens thickness(LT),AL,anterior corneal keratometry,whiteto-white(WTW),pupil diameter(PD),as well as IOL power calculated using embedded Barrett formula were assessed.Bland-Altman plots were used to test the agreement of the binocular parameters.RESULTS:In group A,the CCT of the right eye was significantly thinner than that of the left eye(P=0.044)with a difference of-2±8μm[95%limits of agreement(LoA),-17.8 to 13.2μm].For group B,the PD and IOL power in the right eye were significantly lower than those of the left eye(P=0.001,<0.001)with a difference of-0.05±0.32 mm(95%LoA,-0.68 to 0.58 mm)and-0.18±1.01 D(95%LoA,-2.2 to 1.8 D).The AL of right eye was longer than that of the left eye(P=0.002)with a difference of 0.04±0.25 mm(95%Lo A,-0.45 to 0.52 mm).No significant difference was observed for all the binocular parameters in group C.The percentage of participants with binocular IOL power difference within±0.5 D were 62%(31/50),68.3%(339/496),and 38.8%(66/170)in groups A,B,and C,respectively.CONCLUSION:The binocular parameters related to IOL power are in good agreement,but the binocular IOL power difference of more than half of participants with long AL is more than 0.50 D.

Machine learning adaptation of intraocular lens power calculation for a patient group

Background:To examine the effectiveness of the use of machine learning for adapting an intraocular lens(IOL)power calculation for a patient group.Methods:In this retrospective study,the clinical records of 1,611 eyes of 1,169 Japanese patients who received a single model of monofocal IOL(SN60WF,Alcon)at Miyata Eye Hospital were reviewed and analyzed.Using biometric metrics and postoperative refractions of 1211 eyes of 769 patients,constants of the SRK/T and Haigis formulas were optimized.The SRK/T formula was adapted using a support vector regressor.Prediction errors in the use of adapted formulas as well as the SRK/T,Haigis,Hill-RBF and Barrett Universal II formulas were evaluated with data from 395 eyes of 395 distinct patients.Mean prediction errors,median absolute errors,and percentages of eyes within±0.25 D,±0.50 D,and±1.00 D,and over+0.50 D of errors were compared among formulas.Results:The mean prediction errors in the use of the SRT/K and adapted formulas were smaller than the use of other formulas(P<0.001).In the absolute errors,the Hill-RBF and adapted methods were better than others.The performance of the Barrett Universal II was not better than the others for the patient group.There were the least eyes with hyperopic refractive errors(16.5%)in the use of the adapted formula.Conclusions:Adapting IOL power calculations using machine learning technology with data from a particular patient group was effective and promising.

Intraocular lens power calculation in eyes with previous corneal refractive surgery

Background:This review aims to explain the reasons why intraocular lens(IOL)power calculation is challenging in eyes with previous corneal refractive surgery and what solutions are currently available to obtain more accurate results.Review:After IOL implantation in eyes with previous LASIK,PRK or RK,a refractive surprise can occur because (i)the altered ratio between the anterior and posterior corneal surface makes the keratometric index invalid;(ii)the corneal curvature radius is measured out of the optical zone;and (iii)the effective lens position is erroneously predicted if such a prediction is based on the post-refractive surgery corneal curvature.Different methods are currently available to obtain the best refractive outcomes in these eyes,even when the perioperative data(i.e.preoperative corneal power and surgically induced refractive change)are not known.In this review,we describe the most accurate methods based on our clinical studies.Conclusions:IOL power calculation after myopic corneal refractive surgery can be calculated with a variety of methods that lead to relatively accurate outcomes,with 60 to 70%of eyes showing a prediction error within 0.50 diopters.

Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens

AIM : To evaluate the prediction error in intraocular lens(IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position(ELP).METHODS: Retrospective study including a total of 25 eyes of 13 patients(age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL(Oculentis Gmb H, Germany). In all cases, an adjusted IOL power(P IOLadj) was calculated based on Gaussian optics using a variable keratometric index value(n kadj) for the estimation of the corneal power(P kadj) and on a new value for ELP(ELP adj) obtained by multiple regression analysis.This P IOLadj was compared with the IOL power implanted(P IOLReal) and the value proposed by three conventional formulas(Haigis, Hoffer Q and Holladay Ⅰ).RESULTS: P IOLReal was not significantly different than P IOLadj and Holladay IOL power(P 】0.05). In the Bland and Altman analysis, P IOLadj showed lower mean difference(-0.07 D) and limits of agreement(of 1.47 and-1.61 D)when compared to P IOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELP adj was significantly lower than ELP calculated with other conventional formulas(P 【0.01) and was found to be dependent on axial length, anterior chamber depth and P kadj. CONCLUSION: Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing thekeratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.

Machine learning adaptation of intraocular lens power calculation for a patient group

Background:To examine the effectiveness of the use of machine learning for adapting an intraocular lens(IOL)power calculation for a patient group.Methods:In this retrospective study,the clinical records of 1,611 eyes of 1,169 Japanese patients who received a single model of monofocal IOL(SN60WF,Alcon)at Miyata Eye Hospital were reviewed and analyzed.Using biometric metrics and postoperative refractions of 1211 eyes of 769 patients,constants of the SRK/T and Haigis formulas were optimized.The SRK/T formula was adapted using a support vector regressor.Prediction errors in the use of adapted formulas as well as the SRK/T,Haigis,Hill-RBF and Barrett Universal II formulas were evaluated with data from 395 eyes of 395 distinct patients.Mean prediction errors,median absolute errors,and percentages of eyes within±0.25 D,±0.50 D,and±1.00 D,and over+0.50 D of errors were compared among formulas.Results:The mean prediction errors in the use of the SRT/K and adapted formulas were smaller than the use of other formulas(P<0.001).In the absolute errors,the Hill-RBF and adapted methods were better than others.The performance of the Barrett Universal II was not better than the others for the patient group.There were the least eyes with hyperopic refractive errors(16.5%)in the use of the adapted formula.Conclusions:Adapting IOL power calculations using machine learning technology with data from a particular patient group was effective and promising.

IOL-Master测量硅油填充眼屈光结果分析

目的评价IOL-Master测量硅油填充眼屈光度数的准确性并分析不同因素与术后屈光误差的关系。方法29例(29眼)硅油填充眼行硅油取出联合人工晶状体(IOL)植入术,术前用IOL-Master进行IOL测量。根据不同病因、硅油放置时间、眼轴、术后并发症等因素进行分类,研究术后视力恢复情况及测量误差产生的原因。结果术后视力较术前均有不同程度的提高,屈光度数的平均预测误差为0.329±0.846(-1.5～-2.0D),眼轴长度(P>0.05)、病因[裂孔源性(t=0.478,P=0.637)、黄斑裂孔(t=0.135,P=0.895)]、是否近视(t=0.435,P=0.667)与术后产生的屈光误差均无相关性,硅油存留时间<1年者术后矫正视力恢复好。结论硅油填充眼患者采用硅油取出联合IOL植入术对视力有一定提高,IOL-Master测量硅油填充眼IOL度数是相对准确、安全、方便的方式。

超声乳化联合负度数人工晶状体植入治疗白内障合并超高度近视

目的观察超声乳化白内障吸除联合负度数人工晶状体植入术治疗白内障合并超高度近视的临床疗效。方法对15例(26眼)白内障合并超高度近视眼患者,施行超声乳化白内障吸除联合负度数人工晶状体植入术,记录术前矫正视力、眼轴长度、屈光度数及其与预期屈光度数的偏差值,观察手术并发症和术后眼部情况。结果术前眼轴长度30.12～35.76mm,平均为32.45mm。术中均顺利植入人工晶状体,无后囊破裂发生。植入屈光度数为-1.0～-6.0D,术后1周,24眼视力均有不同程度的提高,最佳矫正视力≥0.2共20眼(76.9%),其中≥0.5者共8眼(30.77%)。2眼因严重的黄斑区网膜萎缩变性,视力无明显提高。术后屈光度数偏差值<±2.00D共22眼(84.6%),<±1.00D共14眼(53.8%)。随访时间为3～24个月。后囊膜皱褶6眼,后发性白内障7眼,5眼行激光后囊膜切开术,无视网膜和脉络膜脱离发生,无眼压升高。4例单眼白内障患者中,1例出现双眼干扰症状。结论超声乳化白内障吸除联合负度数人工晶状体植入既可以进行屈光矫正,又可以增加眼内组织的稳定性,减少视网膜脱离的发生,是治疗白内障合并超高度近视眼安全、有效的方法。

Improving refractive outcomes in cataract surgery: A global perspective

This review summarises the current evidence base and provides guidelines for obtaining good refractive outcomes following cataract surgery. Important background information is also provided. In summary, the requirements are:(1) standardisation of biometry equipment used for axial length and keratometry measurement and the use of optical or immersion ultrasound biometry;(2) sutureless cataract surgery with "in the bag" intraocular lens(IOL) placement;(3) an appropriate 3rd, 4th or 5th Generation IOL power formula should be used;(4) IOL formula constants must be optimized;(5) under certain conditions, the refractive outcome of the 2nd eye can be improved based on the refractive error of the first eye; and(6) results should be audited for refinement and to ensure that standards are met.

IOLMaster 700与IOLMaster 500不同计算公式对白内障眼人工晶状体屈光力计算的准确性比较

目的比较IOLMaster 700与IOLMaster 500不同计算公式对白内障眼人工晶状体(IOL)屈光力计算的准确性。方法采用横断面研究方法,纳入2018年11月至2019年11月在温州医科大学附属眼视光医院接受白内障超声乳化摘出联合IOL植入术治疗的年龄相关性白内障患者262例262眼。分别采用IOLMaster 700和IOLMaster 500进行术前生物测量,采用IOLMaster 700和IOLMaster 500仪器内置公式Haigis、HolladayⅠ、Hoffer Q和SRK/T计算IOL屈光力。本研究以屈光预测误差为指标,比较不同眼轴长度(AL)下受检眼用2种仪器不同计算公式的屈光结果。结果在所有眼轴范围内,IOLMaster 700与IOLMaster 500 Haigis、Hoffer Q、SRK/T公式计算的绝对预测误差平均值(MAE)差异均无统计学意义(均P>0.05),IOLMaster 500 HolladayⅠ计算的MAE为0.47(0.24,0.90)D,小于IOLMaster 700的0.50(0.28,0.99)D,差异有统计学意义(Z=-3.120,P=0.002)。AL<22.0 mm、24.5 mm≤AL<26.0 mm时,4种公式计算的MAE差异均无统计学意义(均P>0.05);22.0 mm≤AL<24.5 mm时,Haigis、Hoffer Q、SRK/T公式计算的MAE差异均无统计学意义(均P>0.05),IOLMaster 500 HolladayⅠ计算的MAE为0.42(0.18,0.75)D,小于IOLMaster 700的0.45(0.25,0.79)D,差异有统计学意义(Z=-3.487,P<0.001),但差异数值很小,无临床意义;AL≥26.0 mm时,Haigis、HolladayⅠ、SRK/T公式计算的MAE差异均无统计学意义(均P>0.05);IOLMaster 500 Hoffer Q计算的MAE为0.66(0.38,1.00)D,小于IOLMaster 700的0.98(0.62,1.32)D,差异有统计学意义(Z=-3.046,P=0.002)。结论所有眼轴范围内,2种仪器Haigis、Hoffer Q和SRK/T公式屈光预测准确性接近。对于长眼轴患者,IOLMaster 700 Hoffer Q公式计算的MAE明显大于IOLMaster 500,临床使用中需谨慎。IOLMaster 700与IOLMaster 500的屈光预测准确性基本接近。

The influence of corneal ablation patterns on prediction error after cataract surgery in post-myopic-LASIK eyes

Purpose:To evaluate the influence of corneal ablation patterns on the prediction error after cataract surgery in postmyopic-LASIK eyes.Methods:Eighty-three post-myopic-LASIK eyes of 83 patients that underwent uneventful cataract surgery were retrospectively included.Predicted postoperative spherical equivalence(SE)was calculated for the implanted lens using the Haigis-L and Barrett True-K formula.Prediction error at one month postsurgery was calculated as actual SE minus predicted SE.For each eye,area and decentration of the ablation zone was measured using the tangential curvature map.The associations between prediction errors and corneal ablation patterns were investigated.Results:The mean prediction error was-0.83±1.00 D with the Haigis-L formula and-1.00±0.99 D with the Barrett True-K formula.Prediction error was positively correlated with keratometry(K)value and negatively correlated with ablation zone area using either formula,and negatively correlated with decentration of the ablation zone using the Barrett True-K formula(all P<0.05).In the K<37.08 D group,prediction error was negatively correlated with decentration of the ablation zone with both formulas(all P<0.05).Multivariate analysis showed that with the Haigis-L formula,prediction error was associated with axial length(AL),K value and decentration,and with the Barrett True-K formula,prediction error was associated with AL and decentration(all P<0.05).Conclusion:A flatter cornea,larger corneal ablation zone and greater decentration will lead to more myopic prediction error after cataract surgery in post-myopic-LASIK eyes.

Comparison of a new optical biometer and a standard biometer in cataract patients

Background:Cataract surgery is the most common surgical procedure in ophthalmology.Biometry data and accurate intraocular lens(IOL)calculations are very important in achieving the desired refractive outcomes.The aim of this study was to compare measurements using a new optical low coherence reflectometry(OLCR)biometer(OA-2000)and the gold standard partial coherence interferometry(PCI)optical biometer(IOLMaster 500).Methods:Ocular biometry of cataract patients were measured by the OA-2000 and IOLMaster 500 to compare keratometry(K),axial length(AL),anterior chamber depth(ACD),white-to-white(WTW)diameter,and IOL power using the SRK/T formula.Results:One hundred and two eyes of 68 cataract patients were evaluated with the two optical biometers.The mean values of the AL,K,ACD,and WTW differed very little(OCLR biometer,23.12 mm,44.50 diopters(D),3.06,and 11.64 mm,respectively;PCI biometer,23.18 mm,44.6 D,3.15,and 11.86 mm,respectively),but the differences were significant(all,p≤0.05).The AL,K,and ACD showed excellent correlations(r=0.999,0.980,and 0.824,respectively;all p<0.001);however,there was a weak correlation of the WTW diameter between the two devices(r=0.256).The IOL powers using the SRK-T formula derived from both instruments were very similar,with an excellent correlation(r=0.989).The mean difference between the two instruments was 0.32 D.Conclusions:The OLCR biometer showed very a strong agreement with the standard PCI optical biometer for almost all ocular biometry measurements,except for the WTW diameter.Trial registration:TCTR20160614003;date 06/09/2016;‘retrospectively registered’.

应用优化计算方法与计算机软件计算角膜屈光手术后人工晶状体屈光力

目的 对准分子激光角膜屈光手术后人工晶状体屈光力的计算方法进行优化,并开发为计算机软件,评价其准确性与可靠性.方法 对人工晶状体屈光力计算方法进行优化,包括：角膜屈光力的矫正计算 人工晶状体有效位置的计算与双K值法（double-K method）的应用 标准化计算公式的应用.将计算方法编写为计算机应用软件（IOL calculator for post-refractive cases）.应用该软件对49例角膜屈光手术后的白内障患者的人工晶状体屈光力进行计算,以白内障手术后实际屈光状态为标准,预测屈光状态与实际屈光状态之间的差异为预测误差,预测误差的绝对值为绝对预测误差.以SPSS 11.0软件分析预测误差与绝对预测误差的平均值与分布.结果 白内障手术后屈光状态为-2.50～0.75 D,平均为（-0.78±o.83）D,3眼（6.1%）为正视,36眼（73.5%）为近视,10眼（20.4%）为远视.预测误差为-1.26～1.96 D,平均（-0.02±0.75）D,接近于正视性屈光状态.绝对预测误差为0～1.96 D,平均（0.62±0.42）D,绝对预测误差≤0.5 D者19眼（38.8%）,＞0.5 D且≤1.0 D者22眼（44.9%）,＞1.0 D且≤1.5 D者7眼（14.3%）,＞1.5 D 且≤2.0 D者1眼（2.0%）.结论 通过优化计算方法与开发计算机软件,可以充分简化准分子激光角膜屈光手术后人工晶状体屈光力的计算过程,并提高计算的准确性与可靠性.