准分子激光屈光性角膜手术后人工晶状体度数的计算

准分子激光屈光性角膜手术后,患者发生白内障需行白内障摘除及人工晶状体植入术时,按常规方法计算人工晶状体屈光度往往会在术后产生远视,而这样的误差主要来源于角膜屈光力的测算误差和计算公式的误差,另外还有眼轴长度测量和有效人工晶状体位置计算的准确性降低这两个方面的原因.因此,对于曾行角膜屈光手术的白内障患者,术前运用适当的方法准确估算角膜屈光力,并选择合适的人工晶状体计算公式,可以减少屈光误差.     

婴幼儿先天性白内障术后眼轴和屈光变化及影响因素

先天性白内障患儿术后的眼轴长度、角膜屈光力和屈光变化规律是手术时机和人工晶状体屈光度选择的重要依据。先天性白内障患儿的眼轴长度增长速率与许多因素,如手术年龄、单双眼发病,术后并发症等有关。术后的近视漂移难以预测,主要由眼轴长度增长决定,同时也受到手术年龄、人工晶状体植入时机以及植入人工晶状体时目标屈光度的计算等多因素影...     

角膜屈光手术后人工晶状体度数计算公式的选择

角膜屈光手术后的患者发生白内障并行人工晶状体置换手术时,如果按常规计算公式选择人工晶状体的度数,往往会在术后产生不同程度的屈光不正,主要来源于角膜屈光力的测算误差和计算公式的误差,以及眼轴长度测量和有效人工晶状体位置计算的准确性降低等方面的原因.因此,对于曾行角膜屈光手术的白内障患者, 术前应运用适当的方法估算角膜屈光力,并正确地选择合适的人工晶状体度数计算公式,从而减少晶状体置换术后引起的屈光误差.     

高度近视白内障患者人工晶状体屈光度数计算公式的选择

目的　比较SRK T(Sanders Retzlaff KvaffT)和SRK Ⅱ (Sanders Retzlaff KvaffⅡ )公式的特点 ,以提高高度近视白内障患者人工晶状体 (intraocularlens ,IOL)屈光度数计算的准确性。方法 (1)使用相同的生物参数 (眼轴长度和角膜屈光力 )和A常数 ,比较SRK T和SRK Ⅱ公式理论计算值的差异 ;(2 )对 86例 (130只眼 )高度近视白内障患者行超声乳化白内障吸除联合IOL植入术。分别采用SRK T和SRK Ⅱ公式计算IOL屈光度数 ,记录并比较不同眼轴长度患者按照两公式计算结果植入IOL术后实际屈光度数与预期屈光度数的差异。随访时间 3～ 2 4个月。结果　 (1)角膜屈光力为 4 3 0 0D时 ,两公式理论计算值比较差异无显著意义 (P >0 0 5 ) ,且两公式计算的屈光度数差值与眼轴长度无相关 (P>0 0 5 ) ;角膜屈光力为 39 0 0、4 1 0 0、4 5 0 0及 4 7 0 0D时 ,两公式理论计算值比较差异均有显著意义(P <0 0 5 ) ,且两公式计算的屈光度数差值与眼轴长度呈中、高度线性正相关 (P <0 0 5 )。(2 )按照SRK T和SRK Ⅱ公式计算结果植入IOL术后 ,术眼实际屈光度数与预期屈光度数差值分别为 0 0 8D和 -0 79D ,差异有显著意义 (P <0 0 5 )。结论　选择IOL屈光度数的计算公式 ,应综合考虑患者的眼轴长度和角膜屈光力等因素 ;其中     

准分子激光角膜屈光术后人工晶状体度数计算的研究进展

曾行准分子激光角膜屈光手术的白内障患者,人工晶状体(IOL)度数的计算一直是个难题,如按常规方法计算,结果会产生较大误差,主要是术后出现不同程度的远视。本文就准分子激光角膜屈光术后角膜屈光力的测算、人工晶状体计算公式选择、前房深度测量、眼轴测量等影响人工晶状体度数计算的多种因素及其解决方法做一综述。     

IOLMaster测量超长眼轴眼人工晶状体计算公式准确性比较

目的 比较IOLMaster测量超长眼轴眼时,各人工晶状体计算公式(Haigis、SRK Ⅱ、Hoffer Q、Holladay 1及SRK/T公式)准确性,指导临床工作中超长眼轴眼人工晶状体计算公式的选择以及术后屈光度的预留.方法 前瞻性临床病例研究.收集以IOLMaster测量眼轴且眼轴长度大于28.5mm的白内障患者34例(46只眼).所有患者均行白内障超声乳化人工晶状体植入术.通过IOLMaster仪器内置软件计算各个人工晶状体计算公式的预测术后屈光度.术后3个月后,验光明确患者实际术后屈光度.比较各个人工晶状体计算公式的预测术后屈光度与实际术后屈光度的直线相关性,绝对预测误差的分布以及预测误差值平均值的差异.结果 各人工晶状体计算公式的预测术后屈光度与实际术后屈光度直线相关系数分别是:Haigis公式r=0.902,SRK Ⅱ公式r=0.696,Hoffer Q公式r=0.871,Holladay 1公式r=0.896,SRK/T公式r=0.783.各人工晶状体计算公式的绝对误差分布均较为分散,仅Haigis公式在1.01～1.50 D百分率超过60％.各人工晶状体计算公式的预测误差平均值分别是:Haigis公式(1.12±0.40) D,SRK Ⅱ公式(0.82±1.53)D,Hoffer Q公式(1.91±0.46) D,Holladay 1公式(1.67±0.41) D,SRK/T公式(1.31 ±0.59)D,除SRK Ⅱ公式外,其他人工晶状体计算公式的预测误差值均为正值.结论 在IOLMater测量超长眼轴眼中,Haigis公式的预测术后屈光度与实际术后屈光度相关性最强,Haigis公式的绝对预测误差值61％分布在1.01～1.50 D,临床应用中可根据Haigis公式预测误差平均值调整术前预留屈光度.     

眼轴长度测量与人工晶状体屈光力计算研究进展

白内障手术的效果受多种因素的影响,如术前生物学参数的测量、人工晶状体屈光力计算公式的选择、手术方式及手术技巧等。眼轴长度是计算人工晶状体屈光力的重要参数,目前测量眼轴长度的主要方法是超声生物测量法及光学生物测量法,这两种方法各有利弊,相辅相成。人工晶状体屈光力的计算公式在过去的几十年里不断更新,在近几年更是出现了很多新的计算公式,如Barrett Universal Ⅱ(BUⅡ)公式、Kane公式、Olsen公式、Hill-radial basis function(Hill-RBF)公式等。本文主要总结了两种眼轴长度测量方法的利弊,并比较不同人工晶状体屈光力计算公式在不同眼轴长度时的准确性。     

改良SRK-T公式预测人工晶状体植入术后散光误差分析

目的 评价改良SRK-T公式对球面人工晶状体植入术后预测散光的可行性及其误差的影响因素,以探讨改良SRK-T公式在散光人工晶状体度数计算中的应用价值.方法 回顾性系列病例研究.分析2007年10月至2008年6月行超声乳化白内障摘除联合球面人工晶状体植入术且资料完整的白内障病例68例（106眼）.比较改良SRK-T公式与SRK-T公式计算得出的术后预测等效屈光度数之间的差异.矢量分析改良SRK-T公式预测的术后散光度与实际术后散光度之间的差异,并采用多元线性回归分析其影响因素.结果 改良SRK-T公式与SRK-T公式计算得出的术后预测等效屈光度结果完全吻合.矢量分析术后散光预测误差结果示：J0预测误差的因素主要是角膜散光（KS）,J0=-0.108-0.102×KS（P＝0.034）.J45预测误差的因素主要是眼轴（L）与角膜平均屈光度（K）,J45=1.797-0.019×L-0.031×K（P=0.009）.结论 改良SRK-T公式的方法可以用于散光人工晶状体植入度数的计算,其误差跟角膜散光、眼轴、角膜平均屈光度有关.     

先天性白内障术后眼轴角膜曲率及屈光度变化

目的 探讨先天性白内障术后患儿眼轴、角膜曲率及屈光度的变化.方法 对49例（84只眼）先天性白内障行晶状体超声乳化手术联合后囊切除及前部玻璃体切除手术,按年龄分为＜3岁、3～5岁及＞5岁3组.术前及术后1年分别测量眼轴长度、角膜曲率;手术后1周及术后1年验光.结果 3组患儿眼轴长度增长量分别为（1.88±0.93） mm,（1.37±0.78） mm及（0.54±0.82） mm,术后眼轴长度变化量随年龄增长而下降,3组间眼轴增长的长度比较差异有统计学意义.3组角膜曲率变化量分别为（-0.12 ±0.08）D,（＋0.09±0.05）D及（-0.06 ±0.02）D.角膜曲率术前和术后1年变化量3组间比较,差异无统计学意义.术后1周到1年屈光度的变化量分别是-2.06 D,-0.42 D和-0.23 D.3组屈光度数均有向近视方向转移的趋势,但随年龄增大,转移趋势变慢.结论 先天性白内障患儿施行白内障摘出合并前部玻璃体切除Ⅰ期人工晶状体植入术,对患儿眼球的发育无明显影响.儿童植入人工晶状体的屈光度选择应该考虑到儿童的年龄及眼轴的变化的影响.     

短眼轴眼不同人工晶状体计算公式准确性比较

目的 比较A型超声测量下6种现代人工晶状体公式(SKT、HAIGIS、HOFFER-Q、SRK-Ⅱ、HOLLADAY、BKINK-Ⅱ)在短眼轴眼(＜22 mm)的准确性应用.方法 前瞻性研究短眼轴白内障眼超声生物参数,人工晶状体植入术前使用A型超声仪、角膜曲率计测量术眼的眼轴长及角膜屈光度,术后1个月电脑验光与检影验光相结合的方法测量术眼获得最佳矫正远视力时的实际屈光度数,回输超声测量的眼轴、角膜屈光度及实际使用的人工晶状体度数,并分别计算术眼用这6种公式的预期屈光度数,预期屈光度与实际屈光度之差绝对值,即绝对屈光误差值.结果 HAIGIS绝对屈光误差最大( 0.9181 ±0.10691)D(P ＜0.01);其他5种公式比较无统计学意义,但SRK-Ⅱ的绝对屈光误差值最小(0.5088±0.07012)D,但在绝对屈光误差值0～0.5 D范围内,SKT公式所占比例最高(34.37％).结论 在目前短眼轴样本量,除HAIGIS外,其他5种公式比较,SRK-Ⅱ的绝对屈光误差值最小,SKT其次;但在绝对屈光误差0～0.5D范围内,SKT公式所占比例最高(34.37％),可见,SKT公式在短眼轴眼提供最准确的预测屈光度;HAIGIS对术后屈光度影响较大,不适合国人短眼轴眼.     

角膜屈光手术后人工晶状体植入度数的计算

目的分析应用 HolladayⅡ公式计算角膜屈光手术后人工晶状体(IOL)植入度数的准确性。方法角膜屈光手术后患者15例(15只眼),分成两组行超声乳化白内障吸除术联合 IOL 植入术。第一组(8只眼)应用 HolladayⅡ公式进行 IOL 度数计算,角膜屈光度根据手术医师经验计算获得,为 KS。第二组(7只眼)应用同一公式,但角膜屈光度应用患者的屈光度数计算获得,为 KR。比较超声乳化白内障吸除术后1个月的屈光度数与术前的预期屈光度数,并应用两者差的绝对值作为标准进行分析。结果两组超声乳化白内障吸除术后1个月的角膜屈光度数与术前预期屈光度数差的绝对值平均值依次为(0.90±0.22)D 和(0.99±0.22)D。结论应用 HolladayⅡ公式计算角膜屈光手术后行超声乳化白内障吸除术时植入 IOL 度数的准确性相对较高。KS 与 KR 在 HolladayⅡ公式中应用的差异无统计学意义。(中华眼科杂志,2006,42:888-891)     

Intraocular lens power calculation for lens exchange

PURPOSE: To examine patients who had intraocular lens (IOL) exchange for large postoperative refractive errors and determine the factors that contributed to the error in IOL power calculation. SETTING: Thirteen affiliated hospitals in Japan. METHODS: This study comprised 34 cases that required IOL exchange because of large refractive errors after primary lens implantation. Patients with intraoperative complications were excluded from the study. The potential contribution of axial length, corneal refractive power, IOL manufacturer, and IOL fixation to errors in the predicted power was examined retrospectively. Axial length was calculated by the SRK/T and Holladay formulas using refraction after primary IOL implantation. RESULTS: There was no statistical difference between the corneal refractive power before and after cataract surgery. The axial lengths calculated using the SRK/T and Holladay formulas were longer than the ultrasonic axial lengths in 24 and 23 cases, respectively. Using IOLs from the same manufacturer for both primary implantation and exchange reduced the error in predicted refraction. CONCLUSION: Axial length and IOL manufacturer were important factors in predicting refraction power in eyes requiring IOL exchange.     

Intraocular lens power calculation and refractive change in pediatric cases

PURPOSE: To evaluate the intraocular power calculation formula for children and the change of the refraction. SUBJECT AND METHODS: We reviewed the medical records of 66 pediatric cases with intraocular lens (IOL) implantation after cataract extraction and results of questionnaire of the Japanese Association of Pediatric Ophthalmology and Japanese Society of Cataract and Refractive Surgery. We employed four IOL power calculation formulae(SRK, SRK II, SRK/T, Holladay) to evaluate the accuracy of preoperative prediction of refraction. RESULTS: The best preoperative prediction was obtained by the SRK formula; the predictive refraction error within +/- 1 D was shown in 65% of patients. SRK/T and Holladay formulas were less accurate in patients aged 5 years old or younger. All formulae were less accurate in patients with axial length of 22 mm or shorter. There was no significant difference in the mean change in refraction over four years among three different age group (group 1: < = 5, group 2: 6 < = 10, group 3: 11 < = 15(years old(YO)). However, several patients aged 10(YO) or younger showed severe myopic changes during this period. CONCLUSION: The IOL power calculation fomulae show less accuracy on pediatric cases. It is also difficult to predict the change of refraction on pediatric cases.     

儿童白内障手术人工晶状体度数计算准确性分析

目的 分析儿童眼人工晶状体度数计算的准确性.方法 回顾性研究37例(62只眼)行先天性白内障摘除加人工晶状体(IOL,intraocular lens)植入术患儿生物测量及屈光状态数据,应用SRKⅡ计算IOL度数.术后2个月行视网膜检影验光检测屈光状态.分析手术年龄,眼轴长度,IOL植入时机与IOL度数计算准确性关系.结果 全部平均绝对预测误差为(1.56±1.43)D.绝对预测误差低于1.0 D共32只眼,占总眼数52%.眼轴≤20 mm组绝对预测误差为(2.75±1.66)D,＞20 mm组为(1.06±0.93)D,2组间差异具有统计学意义(P＜0.01).年龄≤2岁组绝对预测误差为(2.38±1.65)D,＞2岁为(1.04±0.99)D,2组间差别具有统计学意义(P＜0.01).Ⅰ期IOL植入组绝对预测误差为(1.37±1.35)D,Ⅱ期IOL植入为(2.03±1.56)D,2组间差异无统计学意义(P=0.22).结论 全组植入的IOL度数安全有效.眼轴≤20 mm及年龄≤2岁患儿绝对预测误差明显增加.该研究证明,专门为儿童眼设计IOL计算公式是有必要的.

Abstract：

Objective To determine the accuracy of intraocular lens (IOL) power calculation in a group of pseudophakic children. Methods A relrospective analysis of biometric and refractive data was performed on 62 eyes of 37 infants and children, who successfully underwent cataract extraction and IOL implantation. SRKII were used to calculate the IOL power. The postoperative refractive outcome was taken as the spherical equivalent of the refraction at 2 months afier surgery by retinoscopy. The data were analyzed to assess the effects of age at the time of surgery, axial length, and primary or secondary intraocular lens implantation on the accuracy of calculation of IOL power. Results For the overall group the mean and median prediction errors were 1.56D (SD 1.43). There were 32 eyes'absolute predictions errors lower than 1D (52%). The mean absolute prediction errors in eyes with axial lengths≤20 mm were 2.75 D (SD 1.66), and in eyes ＞20 mm were 1.06 D (SD 0.93). The mean absolute prediction errors in eyes in children aged≤2 years were 2.38 D (SD 1.65), and in children aged ＞2 years were 1.04D (SD 0.99). The differences between the absolute prediction errors for both axial length and age were statistically significant (P ＜0.01). The mean-absolute prediction errors in eyes with primary IOL implantation were 1.37D (SD 1.35), and secondary intraocular lens implantation were 2.03D (SD 1.56). The differences between the absolute prediction errors primary or secondary intraocular lens implantation, were not statistically significant (P =.22). Conclusions For the overall group IOL power calculation is generally acceptable. In eyes with axial lengths less than 20 mm and in children younger than 2 years of age larger errors can arise, and the variations increase. This study demonstrates the need for an IOL formula specifically designed for pediatric use.     

Accuracy of intraocular lens power prediction using the Hoffer Q, Holladay 1, Holladay 2, and SRK/T formulas

PURPOSE: To compare the accuracy of intraocular lens (IOL) power calculations using 4 formulas: Hoffer Q, Holladay 1, Holladay 2, and SRK/T. SETTING: Tertiary care center. METHODS: This study was a retrospective comparative analysis. Immersion ultrasound biometry (axial length, anterior chamber depth, and lens thickness), manual keratometry, and postoperative manifest refraction were obtained in 643 eyes of consecutive patients who had routine uneventful cataract surgery with implantation of 1 of 2 IOLs using the same operative technique by the same surgeon. Biometric data were entered into each of the 4 IOL power calculation formulas, and the results were compared to the final manifest refraction. An optimized lens constant was used for each formula. Results were also stratified into groups of short, average, medium long, and very long axial length <22.0 mm, 22.0 to <24.5 mm, 24.5 to 26.0 mm, and >26.0 mm, respectively). RESULTS: No formula was more accurate than the others as measured by mean absolute error. The formulas were also equally accurate when eyes were stratified by axial length. CONCLUSION: The 4 IOL power formulas provided equivalent refractive results in the entire group of eyes and in the subsets of axial lengths tested.     

高角膜屈光力白内障患者人工晶状体屈光力的计算

目的①探讨角膜屈光力异常增大对人工晶状体（intraocular lens，IOL）屈光力计算准确性的影响。②比较不同计算公式对高角膜屈光力患者IOL屈光力计算的准确性。方法对33例（43眼）角膜屈光力高于47D的白内障患者行超声乳化白内障吸除联合IOL植入手术。术前采用Orbscan-Ⅱ眼前节分析系统测量角膜屈光力，根据高斯光学理论和临床资料推导得出IOL屈光力理论计算公式（本方法）。采用本方法、Holladay2、Holladay、Hoffer Q、SRFUT与SRK2公式对IOL屈光力进行计算，植入IOL术后人工晶状体眼实际屈光状态与术前预测值的差异为预测误差（predictive error，PE），预测误差的绝对值为绝对预测误差（absolute predictive error，AE），分别计算不同计算公式的PE与AE。用SPSS11.0软件进行如下分析：①比较不同公式AE的差异。②回归分析不同公式AE与角膜屈光力的相关性。结果①本方法、。Holladay2、Holladay、Hoffer Q、SRK／T与SRK2公式所产生的AE分别为（0.28±0.17）D、（0.24±0.18）D、（0.27±0.17）D、（0.25±0.23）D、（0.59±0.35）D及（0.83±0.48）D，SRK／T与SRK2公式产生的AE高于所研究的其他计算公式，差异具有显著性。②SRK2公式与SRK／T公式的AE分别与角膜屈光力呈正相关（SRK2公式：r^2=0.522，F=44.82，P〈0.01；SRK／T公式：r^2=0.443，F=32.63，P〈0.01），本方法、Holladay2、Holladay及Hoffer Q公式产生的AE与角膜屈光力不相关。结论对于角膜屈光力异常增大的白内障患者，SRFUT与SRK2公式的计算准确性较差，两者的计算误差与角膜屈光力大小相关，本方法、Holladay2、Holladay与Hoffer Q计算的准确性不受角膜屈光力的影响，其计算结果较为可靠。     

Intraocular lens power calculation formulas in Chinese eyes with high axial myopia

PURPOSE: To compare the accuracy of intraocular lens (IOL) power calculation formulas in Chinese eyes with high axial myopia. SETTINGS: Department of Ophthalmology, Tuen Mun Hospital, Hong Kong, China. METHODS: This retrospective study reviewed 125 Chinese patients with high myopia and axial lengths (ALs) longer than 25.0 mm who had cataract surgery during the year 2000. Eyes with pathology or operative complications affecting the refractive status and those with missing data were excluded. In each case, the power of the implanted IOL was used to calculate the predicted postoperative refractive error by 4 IOL power calculation formulas: SRK II, SRK/T, Holladay 1, and Hoffer Q. The predictive accuracy of the formulas was analyzed by comparing the difference between the "actual" and "predicted" postoperative refractive errors. The Student t test was used for statistical analysis. The performance of the formulas in subcategories of long AL was also tested. RESULTS: One hundred twenty-five eyes (110 patients) were studied. Thirty-seven eyes (29.6%) were excluded. The Hoffer Q, Holladay 1, and SRK/T formulas showed a slight tendency toward resultant hyperopia, with a mean of +0.36 diopters (D), +0.53 D, and +0.74 D, respectively. The SRK II caused the largest hyperopic error, with a mean of +1.47 D. All 4 formulas caused a refractive error shift toward myopia in the subcategories of AL >28.0 mm, minus-power IOL, and extracapsular cataract extraction (ECCE). CONCLUSIONS: In Chinese eyes with high axial myopia with an AL longer than 25.0 mm, the 4 formulas caused a slight postoperative hyperopic refractive error that was less in eyes with a minus-power IOL or an AL longer than 28.0 mm and in those that had ECCE. The Hoffer Q formula provided the best predictive result, and Holladay 1 and SRK/T were comparable in IOL power calculation. The SRK II was the least accurate in all subgroups.     

Novel Homozygous CYP1B1 Deletion in Siblings with Primary Congenital Glaucoma

ABSTRACT

Purpose: To retrospectively analyze the potential sources of error for IOL power calculation in patients with X-linked related megalocornea (XLMC).

Methods: Case report and comparative analysis of refractive outcomes in previously reported phacoemulsification procedures in XLMC cases.

Results: A 52-year-old patient with XLMC and cataracts underwent bilateral clear corneal phacoemulsification, capsule tension ring (CTR) insertion, and in the bag intraocular lens (IOL) implantation. Two years after the procedure the IOL remained centrally located and stable in both eyes. In the postoperative refraction, the patient had a large hyperopic refractive error in the right eye, and a moderate hyperopic refractive error in the left eye. A similar pattern was observed in previously reported cases. Pooling all cases together we observed that the Holladay II formula produced more accurate IOL power calculations than the SRK-T formula. Still, both formulas diverged from the ideal IOL power by approximately 1 diopter per mm of axial length in subjects with axial lengths larger than 24?mm.

Conclusion: Axial length seems to be the main source of IOL power calculation error in XLMC patients. Compared to SRK-T the Holladay II formula provides better refractive results, yet both formulas may require further adjustment depending on the axial length.     

高度近视白内障患者人工晶状体屈光度测算公式的研究进展

高度近视白内障患者手术中人工晶状体(IOL)屈光度数预测与常规白内障相比其精确度欠佳,如何做到精确的生物学测量和正确使用人工晶状体计算公式尤为重要.本文分析了近年在高度近视白内障手术术后屈光预测偏差大的原因,以及公式中常数的应用和眼轴长度调节方法,对比了使用晶状体屈光度预测计算公式(Holladay 1,SRK/T,Hoffer Q和Haigis)和第四代晶状体公式的术后屈光结果的异同,为临床使用提供一定的参考.     

角膜屈光手术患者的白内障摘除联合人工晶体植入手术

目的 研究有角膜屈光手术史患者行白内障摘除植入工晶体度数的确定和术中术后并发症.方法 选取有角膜屈光手术史患者4例4只眼,测量患者的眼轴、角膜曲率和前房深度,分别带入Holladay、Binkhorst及其回归公式计算人工晶体度数,对患者行超声乳化白内障吸除联合人工晶体植入术,术后随访3个月,记录裸眼视力、矫止视力和屈光状态.结果 4例均以选择计算结果中最大的人工晶体度数,结合各自不同的情况有所增减,植入了人工晶体,术后屈光状态与预测值的偏差＜1D;1例在手术中出现了透明角膜隧道切口附近的放射状角膜瘢痕裂开,1例在手术后出现了局限在LASIK角膜瓣区域的角膜水肿.结论 采用多个计算公式同时计算,有可能减小误差,其中,Binkhorst二次回归公式的计算结果预测性比较好.