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.

Effect of lens constants optimization on the accuracy of intraocular lens power calculation formulas for highly myopic eyes

AIM: To evaluate the effect of different lens constant optimization methods on the accuracy of intraocular lens(IOL) power calculation formulas for highly myopic eyes.METHODS: This study comprised 108 eyes of 94 consecutive patients with axial length(AL) over 26 mm undergoing phacoemulsification and implantation of a Rayner(Hove, UK) 920H IOL. Formulas were evaluated using the following lens constants: manufacturer’s lens constant, User Group for Laser Interference Biometry(ULIB) constant, and optimized constant for long eyes. Results were compared with Barrett Universal II formula, original Wang-Koch AL adjustment method, and modified Wang-Koch AL adjustment method. The outcomes assessed were mean absolute error(MAE) and percentage of eyes with IOL prediction errors within ±0.25, ±0.50, and ±1.0 diopter(D). The nonparametric method, Friedman test, was used to compare MAE performance among constants.RESULTS: Optimized constants could significantly reduce the MAE of SRK/T, Hoffer Q, and Holladay 1 formulas compared with manufacturer’s lens constant, whereas the percentage of eyes with IOL prediction errors within ±0.25, ±0.50, and ±1.0 D had no statistically significant differences. Optimized lens constant for long eyes alone showed non-significant refractive advantages over the ULIB constant. Barrett Universal II formula and formulas with AL adjustment showed significantly higher accuracy in highly myopic eyes(P<0.001). CONCLUSION: Lens constant optimization for the subset of long eyes reduces the refractive error only to a limited extent for highly myopic eyes.

Analysis of changes in crystalline lens thickness and its refractive power after laser in situ keratomileusis

AIM: To evaluate changes in the anterior chamber depth (ACD), crystalline lens thickness (LT) and its refractive power after laser in situ keratomileusis (LASIK). METHODS: In all cases, the preoperative and postoperative central ACD which were measured with Pentacam, Orbscan, IOL-Master and A-scan ultrasonography, central corneal true net power which was measured with the Pentacam, Orbscan and IOL-Master, axial length (AL) which was measured with IOL-Master and LT which was measured with the A-scan ultrasonography were compared using the paired sample t test. Ocular refractive errors and lens refractive power at corneal plane were calculated and their correlations were also evaluated before and after LASIK. RESULTS: At 1 week after LASIK, LT and crystalline lens refractive power at corneal plane (Dlens) which were associated with the IOL-Master and Pentacam increased significantly (P <= 0.005), ACD decreased significantly (P <= 0.001), but no significant increase was observed in the Diens which was associated with the Orbscan(P=0.261). Significant correlations between the changes in the ocular refractive errors and Diens which were associated with the Pentacam were observed at 1 week and 6 months after LASIK (P = 0.028; P=0.001). CONCLUSION: LT increased significantly after LASIK, and this might partially lead to ACD decrease, Diens increase and a small quantity of myopic regression.

Accuracy of biometric formulae for intraocular lens power calculation in a teaching hospital

AIM: To evaluate the accuracy of three commonly used biometric formulae across different axial lengths(ALs) at one United States Veterans Affairs teaching hospital.METHODS: A retrospective chart review was conducted from November 2013 to May 2018. One eye of each patient who underwent cataract surgery with a monofocal intraocular lens(IOL) was included. The range of postoperative follow-up period was from 3 wk to 4 mo. The Holladay 2, Barrett Universal II, and Hill-Radial Basis Function(Hill-RBF) formulae were used to predict the postoperative refraction for all cataract surgeries. For each formula, we calculated the prediction errors [including mean absolute prediction error(MAE)] and the percentage of eyes within ±0.25 diopter(D) and ±0.5 D of predicted refraction. We performed subgroup analyses for short(AL<22.0 mm), medium(AL 22.0-25.0 mm), and long eyes(AL>25.0 mm).RESULTS: A total of 1131 patients were screened, and 909 met the inclusion criteria. Resident ophthalmologists were the primary surgeons in 710(78.1%) cases. We found no statistically significant difference in predictive accuracy among the three formulae over the entire AL range or in the short, medium, and long eye subgroups. Across the entire AL range, the Hill-RBF formula resulted in the lowest MAE(0.384 D) and the highest percentage of eyes with postoperative refraction within ±0.25 D(42.7%) and ±0.5 D(75.5%) of predicted. All three formulae had the highest MAEs(>0.5 D) and lowest percentage within ±0.5 D of predicted refraction(<55%) in short eyes.CONCLUSION: In cataract surgery patients at our teaching hospital, three commonly used biometric formulae demonstrate similar refractive accuracy across all ALs. Short eyes pose the greatest challenge to predicting postoperative refractive error.

A Numerical Convex Lens for the State-Discretized Modeling and Simulation of Megawatt Power Electronics Systems as Generalized Hybrid Systems

Modeling and simulation have emerged as an indispensable approach to create numerical experiment platforms and study engineering systems.However,the increasingly complicated systems that engineers face today dramatically challenge state-of-the-art modeling and simulation approaches.Such complicated systems,which are composed of not only continuous states but also discrete events,and which contain complex dynamics across multiple timescales,are defined as generalized hybrid systems(GHSs)in this paper.As a representative GHS,megawatt power electronics(MPE)systems have been largely integrated into the modern power grid,but MPE simulation remains a bottleneck due to its unacceptable time cost and poor convergence.To address this challenge,this paper proposes the numerical convex lens approach to achieve state-discretized modeling and simulation of GHSs.This approach transforms conventional time-discretized passive simulations designed for pure-continuous systems into state-discretized selective simulations designed for GHSs.When this approach was applied to a largescale MPE-based renewable energy system,a 1000-fold increase in simulation speed was achieved,in comparison with existing software.Furthermore,the proposed approach uniquely enables the switching transient simulation of a largescale megawatt system with high accuracy,compared with experimental results,and with no convergence concerns.The numerical convex lens approach leads to the highly efficient simulation of intricate GHSs across multiple timescales,and thus significantly extends engineers’capability to study systems with numerical experiments.

Stability of the Barrett True-K formula for intraocular lens power calculation after SMILE in Chinese myopic eyes

AIM: To compare the Barrett True-K formula with other formulas integrated in Lenstar 900 to predict intraocular lens(IOL) power after small-incision lenticule extraction(SMILE).METHODS: A theoretical prospective study was performed to predict the ratio of equivalent IOL power before and after SMILE using the SRK/T(Sanders, Retzlaff, Kraff/theoretical), Holladay 1, Haigis, and Barrett True-K formulas and compare the stability of their predictions. The study included 54 eyes(54 cases) with a manifest refraction spherical equivalent(MRSE) of-4.99±1.45 D. They were divided into two groups: 27 eyes with axial length of 24-26 mm in Group A, and 27 eyes with axial length >26 mm in Group B. All subjects enrolled in this study were examined with the Lenstar 900 before and 6 mo after SMILE including measurements of axial length, corneal curvature, and anterior chamber depth(ACD). RESULTS: The prediction of equivalent IOL power of the two groups was more stable for the Barrett True-K formula, especially in long axial length eyes(Group B). The respective percentages for the SRK/T, Holladay 1, Haigis, and Barrett True-K formulas were 7.4%, 7.4%, 85.19%, and 88.89% for a margin of error within 0.5 D;25.92%, 51.84%, 100%, and 100% for a margin of error within 1.0 D in Group A;33.33%, 40.74%, 44.44%, and 81.48% for a margin of error within 0.5 D;and 44.44%, 59.26%, 66.66%, and 92.59% for a margin of error within 1.0 D in Group B. The respective percentages for Barrett True-K formulas were 100% for a margin of error within 2.0 D in Group B.CONCLUSION: Theoretically, the Barrett True-K formula provides more stable predictions than other formulas for cataract eyes after SMILE.

High Brightness,High Power Density Fiber Coupling of High Power Laser Diode

The output radiation from the 100μm×1μm aperture of a high power Laser Diode (LD) is efficiently coupled into a 50μm multimode optical fiber.The fiber output of the high power LD with high brightness and high power density is achieved.The power density is up to 3 6×104W/cm2 and the coupling efficiency is 70%.The extreme divergence and the astigmatism of high power LDs require the optics with complex lens structures and high performance.A double-curved lens with two crossed cylindrical lenses structured on both sides of the glass substrate is used in the coupling system.

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.

Generation of 15 W femtosecond laser pulse from a Kerr-lens mode-locked Yb:YAG thin-disk oscillator

We demonstrated a robust power-scalable Kerr-lens mode-locked（KLM） operation based on a Yb：YAG thin-disk oscillator.15-W,272-fs pulses were realized at a repetition rate of 86.7 MHz with an additional Kerr medium and a 2.5 mm hard aperture in the cavity.247-fs pulses with an average power of 11 W could also be obtained by using a 2.4 mm hard aperture.Based on this shorter pulse,high efficient second-harmonic generation（SHG） was performed with a 1.7-mm-long Li B3O5（LBO） crystal.The SHG laser power was up to 5 W with the power fluctuation RMS of 1% measured over one hour.

囊袋张力环对高度近视患者Barrett universalⅡIOL计算公式准确性的影响

目的:评估囊袋张力环(CTR)对Barrett universalⅡ人工晶状体(IOL)计算公式在高度近视合并白内障患者术后屈光状态的稳定性与准确性的影响。方法:本研究为前瞻性研究。选取2022-01/06于我院就诊的高度近视白内障患者40例80眼。采用随机数字表法分为CTR组和空白组,每组40眼,所有患者均用IOL Master测量,并按照Barrett universalⅡ公式计算实际植入IOL屈光度及预测术后屈光度。记录患者术后6 mo的裸眼视力(UCVA)、最佳矫正视力(BCVA),比较术后6 mo两组平均绝对屈光误差(MAE),评估术后屈光状态的稳定性及预测术后屈光度与CTR的关系。结果:术后6 mo两组患者UCVA、BCVA均较术前改善(P>0.05),不同时间点两组UCVA、BCVA比较无差异(均P>0.05);80眼按照Barrett universalⅡ公式植入IOL后,CTR组预计术后屈光度为-2.01±0.71 D,术后实际屈光度为-1.64±0.88 D,MAE为0.37±0.98 D;空白组预计术后屈光度为-2.12±0.64 D,术后实际屈光度为-1.54±0.88 D,MAE为0.58±0.31 D,组间比较有差异(P<0.05)。根据眼轴长度进行分组,对于任意眼轴长度CTR的植入均能有效地减少屈光误差(P>0.05)。随着眼轴的增长,MAE的值越大,眼轴≥30 mm的患者术后MAE值比较两组间有差异(P<0.05)。CTR组、空白组中出现远视漂移的比例分别是18%(7/40)、30%(12/40),组间比较有差异(P<0.05)。结论:对高度近视合并白内障患者,Barrett universalⅡ公式在预测术后屈光度方面具有较高的准确性,术中植入CTR既能够保持囊袋的形态,有效防止术中晶状体悬韧带断裂,使IOL居中性更佳,又能有利于白内障患者术后屈光度的早期稳定,并提供更加稳定的屈光结果,减少屈光漂移。对于术中考虑植入CTR的近视患者,建议术前增加-0.50 D的预留屈光度,以达到理想屈光状态。

Effects of laser beam welding parameters on mechanical properties and microstructure of AZ31B magnesium alloy

The effects of laser beam welding process parameters such as laser power,welding speed and focal position on mechanical properties and microstructure of AZ31B magnesium alloy were studied.Nine joints were fabricated using different levels of laser power,welding speed and focal position.Tensile properties of the welded joints were evaluated and correlated with the weld zone microstructure and hardness.It is found that the joints fabricated using a laser power of 2 500 W,welding speed of 5.5 m/min and focal position of-1.5 mm yield superior tensile properties compared with the other joints.The formation of very fine grains in weld region,higher fusion zone hardness and uniformly distributed finer precipitates are the main reasons for superior tensile properties of these joints.

Joint Optimization Scheme Based on Beam Selection and Interference Cancellation in Lens Millimeter Wave NOMA Systems

Non-orthogonal multiple access(NOMA)has been integrated in millimeter-wave(mmWave)Massive MIMO systems to further enhance the spectrum efficiency, but NOMA has not been fully considered in lens mmWave systems. The fusion of these two technologies requires the joint design of beam selection and interference cancellation. In addition, when users follow the spatial cluster distribution, although the user clustering schemes based on K-means algorithm have been applied, the influence of the virtual and actual cluster center users on achievable sum rate has not been differentiated and analyzed in detail. To solve the above problems, a joint optimization scheme is proposed to maximize the achievable sum rate. The optimization problem is NP-hard, which is solved by using the divide-and-conquer approach. Concretely,based on the signal power loss analysis of directional deviation, a beam selection algorithm is designed for inter-cluster interference cancellation based on the Kmeans algorithm. Further for intra-cluster interference cancellation, a power allocation algorithm based on the bisection method is designed to guarantee the fairness of users in each cluster. The simulation results show that the proposed scheme offers a significant performance improvement in terms of both achievable sum rate and energy efficiency, and it is suitable for the large-scale user scenario due to its low complexity.

Study of ghost image suppression in polarized catadioptric virtual reality optical systems

Backgrounds This paper introduces a polarized catadioptric virtual reality optical system.With a focus on the issue of serious ghost image in the system,root causes are analyzed based on design principles and optical structure.Methods The distribution of stray light is simulated using Lighttools,and three major ghost paths are selected using the area of the diffuse spot,S d and the energy ratio of the stray light,K as evaluation means.A method to restrain the ghost image through optimization of the structure of the optical system by controlling the focal power of the ghost image path is proposed.Results/Conclusions The results show that the S_(d) for the ghost image path increases by 40%and K decreases by 40%after optimization.Ghost image is effectively suppressed,which provides the theoretical basis and technical support for ghost suppression in a virtual reality optical system.

Investigation of the performance of the dish/stirling solar thermal electricity system

A dish/stifling solar thermal electricity system consists of two parts： a dish solar concentrator and a Stifling engine. For optimizing the system, in this paper, the mathematical model for concentrator design was established and the effects of those design parameters of concentrator, such as the size and intensity of the focal point, the receiver temperature, on the efficiency of the Stifling engine and output power were numerically simulated. The results of the simulation revealed a close relationship between power and efficiency because of power losses, and there was a maximum for the engine efficiency and power with increasing solar radiation because there was a peak value of system efficiency with increasing receiver temperature. So, in view of our Stifling engine, the 450 rim angle and 6m focal length are optimal design for concentrator and the 800℃receiver temperature is best.

The associations of lens power with age, axial length and type 2 diabetes mellitus in Chinese adults aged 50 years and above

Background:To investigate the associations of lens power with age,axial length(AL),and type 2 diabetes mellitus(DM)inChineseadultsaged5oandabove.Methods:Random clustering sampling was used to identify adults aged 50 years and above in urban regions of Shanghai.The participants underwent a comprehensive ophthalmic examination including subjective refraction,autorefraction,and IOL-Master.The crystalline lens power was calculated using Bennett's formula.Results:A total of 4177 adults were included.A linear decrease in lens power was observed both with age and with AL,followed by a stop of lens power loss after the age of 70 or when AL≥25 mm,respectively.Participants with type 2 DM presented higher lens power(0.43 diopter(D),P<0.001)and thicker lens thickness(0.06 mm,P<0.001).In multivariate regression models,there was a positive correlation between lens power and type 2 DM when age<75 years(P<0.001)or AL<25 mm(P<0.001)after adjusting for other factors,while no significant association was found in participants aged≥75 years(P=0.122)or with AL≥25 mm(P=0.172).Conclusions:The lens power in adults aged 50 and above exhibited two stages with age and with AL.Type 2 DM caused an increase in lens power,which was not seen in participants aged≥75 years or with AL≥25 mm.

The associations of lens power with age,axial length and type 2 diabetes mellitus in Chinese adults aged 50 and above

Background:To investigate the associations of lens power with age,axial length(AL),and Type 2 diabetes mellitus(DM)in Chinese adults aged 50 and above.Methods:Random clustering sampling was used to identify adults aged 50 years and above in urban regions of Shanghai.The participants underwent a comprehensive ophthalmic examination including subjective refraction,autorefraction,and IOL-Master.The crystalline lens power was calculated using Bennett’s formula.Results:A total of 4177 adults were included.A linear decrease in lens power was observed both with age and with AL,followed by a stop of lens power loss after the age of 70 or when AL≥25 mm,respectively.Participants with Type 2 DM presented higher lens power(0.43 diopter(D),p<0.001)and thicker lens thickness(0.06 mm,p<0.001).In multivariate regression models,there was a positive correlation between lens power and Type 2 DM when age<75 years(p<0.001)or AL<25 mm(p<0.001)after adjusting for other factors,while no significant association was found in participants aged≥75 years(p=0.122)or with AL≥25 mm(p=0.172).Conclusions:The lens power in adults aged 50 and above exhibited two stages with age and with AL.Type 2 DM caused an increase in lens power,which was not seen in participants aged≥75 years or with AL≥25 mm.

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.

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.

近视眼LASIK术后人工晶状体屈光度测算中矫正角膜曲率的回归公式建立及其效能检验

【目的】探讨近视眼LASIK术后测算人工晶状体屈光度时不需要其术前资料的方法。【方法】本研究分为两部分,研究的第一部分是通过对97例(193眼)接受近视眼LASIK手术的病人,记录其术前及术后3个月的等效球镜以及由IOLMaster测量的平均角膜曲率(Km),并应用临床病史法计算出术后3个月时的实际角膜曲率(Kchm),建立Kchm对术后平均角膜曲率(Km-post)的回归公式。研究的第二部分是选取另外67例(132眼)拟接受近视眼LASIK手术的病人,在LASIK术前及术后3个月后将等效球镜设定为目标屈光度,应用在研究第一部分中建立的回归公式来矫正LASIK术后角膜曲率,应用IOLmaster自带的不同人工晶状体屈光度计算公式计算并进行分析比较。【结果】在研究的第一部分中,建立Kchm对Km-post的的回归模型为:Kchm=1.033×Km-post-2.192,模型决定系数R2=0.916。在研究的第二部分中,分析比较由回归公式矫正的术后角膜曲率输入不同人工晶状体屈光度计算公式的计算结果,对于选定的3种人工晶状体类型,与术前等值人工晶状体屈光度差值在±1.0D内者,应用Holladay I和SRK-T公式的准确性优于Haigis、Hoffer-Q公式。【结论】建立了不需要术前数据的矫正近视眼LASIK术后角膜曲率的回归公式,将对该类病人因白内障需要行人工晶状体植入而又缺失LASIK术前数据时有实用价值。

IOL-Master对高度近视眼人工晶状体度数测量的临床研究

目的通过比较非接触式光学相干生物测量仪(intraocular len-master,IOL-Master)与传统超声生物测量法联合角膜曲率计测量法对高度近视眼人工晶状体度数测量的准确性及特点,评价IOL-Master的临床应用价值。方法高度近视且患有老年性白内障的患者19例30眼,术前分别用IOL-Master、超声波生物测量仪联合角膜曲率计测量眼轴长度和角膜曲率,使用SRK/T公式计算人工晶状体度数。对患者施行白内障超声乳化摘出术,按照超声波检查法得出的人工晶状体度数植入可折叠人工晶状体。术后1个月随诊检查视力及眼屈光度。结果超声波检查法和IOL-Master检查得出的眼轴分别是(28.789±1.853)mm和(29·057±1·828)mm,2者相比差异有统计学意义(P=0.001<0·05);角膜曲率计和IOL-Master测量角膜曲率分别为43·336±1·439和43.548±1.445,2者相比差异有统计学意义(P=0·02<0.05)。术后1个月患者平均绝对屈光误差值(meanabsolute refractive error,MAFE):IOL-Master为0～1.25D,平均(0.517±0.273)D,A超联合角膜曲率计为0～1.75D,平均(0.792±0.386)D,2者相比差异有统计学意义(P=0.001<0.05)。IOL-Master和A超联合角膜曲率计的MAFE为0～0·50D者分别占70.0%和43·3%,χ2检验差异有统计学意义(χ2=4.019,P<0·05)。IOL-Master和A超联合角膜曲率计的MAFE为0～1.00D者分别占86.7%和73.3%,χ2检验差异无统计学意义(χ2=1·531,P>0.05)。结论IOL-Mas-ter是一种高精确性、非接触性、操作简单、安全可靠的人工晶状体度数测量工具。与A超相比,IOL-Master对眼轴长度测量精确性较高,尤其是对高度近视眼患者。