Intraocular lens power calculation after keratorefractive surgery

The number of keratorefractive procedures designed to correct refractive errors has dramatically increased over the last few years. The techniques for cataract extraction and intraocular lens implantation have evolved into a refractive surgical procedure as well as an operation to improve best corrected visual acuity and/or spectacle independence. The calculation of intraocular lens power for a desired refractive target can be challenging in post-refractive surgically treated eyes, given the frequent case reports of "refractive surprises" after cataract surgery. After corneal refractive surgery, the direct use of the measured topographic or keratometric values, with no correction, results in less accurate calculation of intraocular lens (IOL) power required for cataract surgery than calculation in virgin eyes. After laser refractive surgery for myopia, this could result in an overestimation of the corneal power and subsequent underestimation of the IOL power, therefore leading to a hyperopic outcome after phacoemulsification. Conversely, after laser refractive surgery for hyperopia, inaccuracy in the keratometric power estimation could result in a myopic outcome after phacoemulsification. Despite current progress in this subject, awareness of the shortcomings of classical methods and suggested strategies to improve accuracy can be valuable to clinicians. This article provides an overview of the possible sources of error in intraocular lens power calculation in post-keratorefractive patients, and reviews the methods to minimize intraocular lens power errors.     

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.     

角膜屈光术后人工晶状体度数计算的临床观察

目的：探讨角膜近视屈光术后白内障患者的人工晶状体度数的计算方法,观察初步的临床效果。方法：回顾性分析2013－03／2015－06于我院行白内障手术同时伴有角膜近视屈光手术史的患者14例23眼。根据患者既往角膜手术方式分为 LASIK （ laser in situ keratomileusis）组9例15眼,RK（ radial keratotomy）组5例8眼。将每例患者的角膜地形图中央2．5 mm最低点曲率值,带入SRK－T公式,按照预留－1．00～－1．50 D选择人工晶状体度数,完成常规的白内障超声乳化联合人工晶状体植入术。术后随访3mo,观察术后视力、矫正视力和屈光状态。计算出术后人工晶状体计算公式的预测屈光误差,分别与www．iolcalc．org网站上的Shammas公式和Barrett True K公式进行比较,观察其应用效果,采用独立样本t检验进行统计分析。结果：LASIK组和RK组相比,两组患者术后3 mo的裸眼视力（LogMAR）分别是0．15±0．11、0．21±0．16,术后屈光度分别是－0．43±1．04、－1．52±1．01D,SRK－T公式预测屈光误差分别是－0．71±0．80、0．43±0．99,LASIK组均优于RK组且两组间差异均有统计学意义（ P＜0．05）。将本研究方法分别与Shammas公式和Barrett True K公式相比,观察各种公式的预测屈光误差,本研究方法的屈光误差最小,但是差异无统计学意义（P＞0．05）。结论：应用研究方法的术后屈光状态均为轻度近视,适用于因近视行角膜屈光手术的白内障患者进行人工晶状体度数的选择,此方法对于LASIK手术史患者的人工晶状体度数预测性更佳。     

角膜屈光手术后患者的白内障手术治疗

角膜屈光手术后年龄相关性白内障以及并发性白内障患者白内障手术治疗时与正常白内障患者有许多不同,术前屈光状态的检查使用IOLMaster能采集更准确的数据,术中无晶状体状态下使用波前像差仪计算精确的人工晶状体度数,同时选择合适的非球面和多焦点等高端人工晶状体来提高视觉质量,以及采用新型的光调节人工晶状体在白内障术后可以无创地调节术后屈光状态,获得最精准的屈光度数,最终使角膜屈光手术后白内障患者在白内障术后达到满意的视觉效果.     

角膜屈光矫正手术后白内障手术

目的:探讨角膜屈光矫正手术后白内障手术的诊疗特点。方法:对2005/2008年间于我院就诊的4例角膜屈光矫正手术后白内障患者行白内障超声乳化吸出术+人工晶状体植入术。依据患者提供的角膜屈光手术资料,分别采用临床病史法或角膜后表面曲率法计算矫正角膜曲率及人工晶状体度数。术后随访观察角膜情况、手术并发症、裸眼视力、最佳矫正视力、术后屈光状态等。结果:术后最佳矫正视力较术前明显提高。术后稳定屈光度与手术前预留屈光状态比较误差范围为-1.00～+1.25D。结论:对角膜屈光手术后的白内障患者施行白内障超声乳化吸出术+人工晶状体植入术是可行的。然而只有了解这类患者病情特点,掌握手术前后诊疗方法,准确计算人工晶状体度数,才能达到满意的疗效。     

儿童白内障手术后二期人工晶状体植入的探讨

目的 探讨儿童白内障术后二期人工晶状体植入术的效果。方法 回顾了34例(41眼)儿童白内障手术后二期人工晶状体植入5年记录。介绍了二期人工晶状体植入的适应证，人工晶状体植入的手术方法。术前、术后视力、屈光不正。双眼状态和手术方法。结果 34例(41眼)儿童白内障手术后二期人工晶状体植入。其中8眼成功囊袋内植入，28眼睫状沟植入，余5眼行后房人工晶状体悬吊术。41眼中35眼(85．37％)有可测量的视力提高，有3眼视力降低2行。24眼(58．54％)与对侧眼的矫正屈光度差在 1．50D以内。31眼(75．61％)屈光度差在 3．00D以内。结论 对于不能耐受接触镜或眼镜的儿童无晶状体眼，二期后房型人工晶状体植入是一种安全、有效的选择。     

非正常眼轴眼前节参数测量和IOL度数计算公式研究进展

屈光性白内障手术的良好效果取决于多种因素,主要包括术前精确的生物测量和人工晶状体(IOL)度数的准确计算。非正常眼轴术前眼部生物测量精确性较低,且术后屈光状态预测与正常眼轴眼相比误差较大,这为获得术后最佳视觉质量带来了很大挑战。近期,新型光学生物测量仪的临床应用,个体化的IOL度数计算公式的研发和应用,使IOL度数选择更加精确。本文针对非正常眼轴白内障患者术前眼部参数测量及IOL度数计算公式的选择近3a最新相关研究进展进行综述,以期为临床应用提供参考。     

小切口手法碎核白内障摘除术治疗白内障合并高度近视

目的:观察小切口手法碎核白内障摘除术治疗白内障合并高度近视的临床效果和安全性。方法:对61例78眼采用小切口手法碎核白内障摘除术联合低度数大直径人工晶状体植入术,观察术后视力,屈光状态及手术并发症。术后随访6～24mo。结果:78眼均成功植入人工晶状体,视力都有不同程度的提高,术后3mo时最佳矫正视力<0.1者2眼,0.1～0.4者26眼,>0.4者50眼;大部分患者残留低度的近视屈光状态;后囊膜混浊12眼;术中未发生前囊膜撕裂和后囊膜破裂等并发症;无视网膜脱离和黄斑囊样水肿的发生。结论:小切口手法碎核白内障摘除术联合低度数大直径人工晶状体植入术治疗白内障合并高度近视,具有临床效果佳、手术安全性高及并发症少的优点,在经济条件相对落后的地区,值得推广应用。     

Conductive keratoplasty: an approach for the correction of residual hyperopia in post-lasik pseudophakia

Although there are many formulae for the calculation of intraocular lens power in the eyes with previous kerato-refractive surgeries, unexpected refractive bias still exists. Hyperopic bias is particularly disliked because it affects both uncorrected distance and near visual acuity. Surgical treatment of the residual hyperopia for the eyes with both laser in situ keratomileusis and cataract surgery remains to be a big problem. Conductive keratoplasty has been shown to be an effective, safe and predictable method for low and moderate hyperopia in the pseudophakic eyes or in the eyes with kerato-refractive surgeries. However, the efficacy and safety of conductive keratoplasty in the correction of residual hyperopia after both corneal and lens refractive surgeries has not been reported. Herein, we reported the surgical correction with conductive keratoplasty for cases of residual hyperopia with/without astigmatism after previous laser in situ keratomileusis for high myopia and following phacoemulsification combined with posterior intraocular lens implantation for complicated cataract.     

葡萄膜炎并发白内障手法小切口手术临床疗效

目的 探讨手法小切口白内障手术人工晶状体植入治疗葡萄膜炎并发白内障的临床疗效.方法 32例（32眼）炎症静止3月以上的葡萄膜炎并发性白内障,行手法小切口白内障手术人工晶状体植入,术后随访3～6月,观察视力、眼压和并发症.结果 32眼术后视力均有提高,其中≥0.5者14眼,0.3～0.4者12眼,0.1～0.2者6眼.瞳孔圆形或椭圆形,术后眼压控制在正常范围.手术并发症为早期角膜水肿及葡萄膜炎反应.结论 葡萄膜炎并发白内障手法小切口白内障手术人工晶状体植入,手术安全,并发症少,术后反应轻,视力有恢复.     

角膜屈光手术后的人工晶状体度数计算

角膜屈光手术后用现行的角膜曲率检测方法测量角膜屈光力不精确,导致该类患者白内障手术时人工晶状体度数计算偏低,术后呈较严重的远视状态。随着接受准分子激光角膜屈光手术人数的增加,此问题在未来将日益突出。围绕这一问题,不少学者提出多种修正方案,以期提高角膜屈光手术后人工晶状体度数计算的准确性,本文就此进行综述。     

Multifocal intraocular lenses

PURPOSE OF REVIEW: Multifocal intraocular lenses (IOLs) are growing in popularity among patients and surgeons, and opened the way to refractive lens exchange. Still they are not used routinely in cataract surgery, for reasons probably connected to the frequently observed reduction in contrast sensitivity. Recent papers with clinical study outcomes can help in understanding the advantages and the limits of multifocal IOLs. RECENT FINDINGS: Emerging from every published study, both refractive and diffractive multifocal IOLs usually provide good near visual acuity with distance correction. As many multifocal IOLs are distance-dominant, near vision can be improved by correcting for near the distance focus. The near contrast sensitivity thus obtained is similar to that of monofocal IOLs. Multifocal IOLs have been employed with success in complicated cataract surgery and in trauma cases, with the same outcome as in normal cataract cases. Presbyopic lens exchange remains controversial, with a high success rate in original ametropic eyes, but limited success in original emmetropic eyes. Secondary procedures to improve the refractive outcome are usually of little efficacy in improving patient satisfaction. A new anterior chamber phakic multifocal IOL has been designed to correct presbyopia and small refractive errors. The first clinical results indicate high patient satisfaction, with 7.3% explantation rate. SUMMARY: Multifocal IOLs can be more widely used after cataract surgery, but should be used with caution in almost emmetropic eyes with little or no cataract. Refractive lens exchange with multifocal IOL is especially worthwhile in hyperopic eyes. The new phakic multifocal IOL adds the concept of reversibility to presbyopic lens exchange.     

手法小切口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

目的:探讨手法小切口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眼的临床疗效。方法:对因白内障合并超高度近视眼行小切口联合负度数人工晶状体植入术的75例98眼患者进行回顾性研究,记录术前眼轴长度和术后视力、屈光度数及其与预期屈光度数的偏差值(屈光度数偏差值),观察手术并发症和术后眼部情况。术后随访6～12mo。结果:术前平均眼轴长度为32.05±1.78mm。术后最佳矫正视力≥0.2者66眼(67.3%);≥0.5者43眼(43.9%),术后屈光度数偏差值<±1.00D者48眼(49.0%);<±2.00D者78眼(79.6%)。术中后囊膜破裂3眼。术中出现后弹力层部分脱离1例。术后角膜不同程度水肿21眼。术后6mo有13眼出现后囊混浊,经Nd:YAG激光切开后视力恢复。未见发现视网膜脱离、继发性青光眼、黄斑囊样水肿、人工晶状体移位等并发症。术后2眼出现双眼干扰症状,经过3mo后行另一眼人工晶状体植入术,术后症状消除。结论:手法小切口白内障摘除负度数人工晶状体植入术是治疗白内障合并超高度近视眼安全、有效的方法。     

Difficult lens power calculations

PURPOSE OF REVIEW: Although cataract extraction seems to be feasible without major technical obstacles, the surgical technique has changed completely, and patients are no longer satisfied with good spectacle-corrected vision but anticipate complete visual rehabilitation after cataract surgery, without correction. To fulfill this desire, toric or accommodative intraocular lenses are of increasing popularity, and the intraocular lens power calculation after keratorefractive surgery has been improved. RECENT FINDINGS: In this review article, we provide an overview of different mathematical strategies of calculating the intraocular lens power with standard formulas and with new algorithms, such as paraxial or numeric ray-tracing. These enhanced techniques may improve the validity of lens power calculation due to reduction of the prediction error, especially in cases with high or excessive corneal astigmatism and after refractive laser surgery. Furthermore, a new calculation scheme for the determination of bitoric eikonic intraocular lenses allows a distortion-free imaging in astigmatic eyes. The biometric determinants for the different formulas and calculation schemes are discussed in detail. SUMMARY: In difficult cases, standard calculation schemes are overemployed and new mathematical algorithms are necessary to adequately address these problems. Ray-tracing algorithms and other complex mathematical computation schemes are of increasing interest and will more and more replace conventional calculation formulas for determination of intraocular lens power.     

视网膜色素变性合并白内障患者人工晶状体植入术

目的 探讨白内障人工晶体状体植入术对视网膜色素变性合并白内障患者治疗的手术技巧及效果。方法 对15例18眼视网膜色素变性合并白内障患者作囊外摘出联合后房型人工晶状体植入或超声乳化吸出晶状体并植入软性人工晶状体。对手术前后视力及并发症进行观察,并追踪观察视功能改变。结果 术后16眼视力较术前提高,视野部分有所改善,ERG无明显改变。结论 白内障人工晶状体植入术对大部分视网膜色素变性并发白内障患者的视力提高有帮助,是一种较为安全有效的治疗方法。     

Long-term follow-up of eye growth in pediatric patients after unilateral cataract surgery with intraocular lens implantation.

PURPOSE: To evaluate the refractive status, axial length, and refractive power of the cornea in pediatric patients after unilateral cataract surgery and intraocular lens implantation. METHODS: Refractive state, refractive power of cornea, and axial length were measured both in the operated and nonoperated eyes in 15 patients (age at surgery = 5 to 15 years; mean, 10.3) before and 4 to 15 years (mean, 9.7) after unilateral cataract surgery. RESULTS: After surgery, visual acuity was 20/40 or better in 79% of operated eyes. Myopic changes, representing the difference between postoperative refraction at last follow-up and postoperative refraction at 1 year after surgery, were noted in the operated eyes at the end of study (mean, -5.02 D), but there were no significant differences in axial length (Wilcoxon signed rank test P >.05) or refractive power of the cornea between operated and nonoperated eyes (paired Student t test P >.05). CONCLUSION: Myopic shift after cataract surgery with intraocular lens implantation may occur even in older children.     

重视悄然来临的“屈光手术后时代”

中国作为近视大国，其屈光手术从最早的放射状角膜切开手术到今天的全飞秒激光小切口角膜基质透镜取出术和有晶状体眼后房型人工晶状体植入术，已经历了20～30年的高速发展时期，这从很大程度上解决了许多近视患者的脱镜问题。然而，随着时间的流逝，早期接受屈光手术的患者们逐渐开始出现白内障，这也意味着“屈光手术后时代”的悄然来临。在该时代背景下，中国的白内障手术医师需要做充分准备以应对：角膜屈光手术后人工晶状体度数计算准确性的提高、有晶状体眼后房型人工晶状体的取出和最大程度满足这些患者的脱镜意愿等方面的挑战。     

葡萄膜炎并发白内障的手术治疗

目的:探讨葡萄膜炎并发白内障施行超声乳化吸除人工晶状体植入治疗的临床效果。方法:对19例21眼稳定的葡萄膜炎并发白内障患者行超声乳化吸除晶状体植入术,术中根据虹膜粘连的程度和范围,分别采用不同的方法处理粘连虹膜及小瞳孔。结果:患者19例21眼术后19眼视力改善,总有效率90%,其中术后视力≥0.3者15眼(71%)。术后无严重并发症发生,无葡萄膜炎加重。结论:超声乳化吸除人工晶状体植入术是治疗葡萄膜炎并发白内障的有效方法。术前控制炎症稳定3mo,术中掌握处理虹膜粘连及小瞳孔的要点,慎重操作,可减少术后并发症,改善患者视功能。     

超声乳化白内障吸出联合人工晶状体植入治疗视网膜色素变性合并白内障

目的 探讨超声乳化白内障吸出联合人工晶状体植入治疗视网膜色素变性合并白内障的疗效.方法 回顾性研究.对2012年1月至2016年12月在乐山市人民医院眼科确诊为原发性视网膜色素变性合并白内障患者给予超声乳化白内障吸出联合人工晶状体植入术52例(101眼)患者的临床资料进行回顾性分析.所有患者治疗前后均进行最佳矫正视力、眼压、裂隙灯前节检查、睫状肌麻痹下眼底检查以及光学相干断层扫描检查.白内障手术均顺利完成,术后随访3 ～ 12(5.09±2.20)个月.患者手术前、手术后各指标的比较用配对t检验,视力提高幅度与黄斑厚度的相关关系采用Pearson相关检验.结果 101眼患眼最佳矫正视力由术前0.12±0.09提高至术后0.21±0.16,差异有统计学意义(t=-8.016,P=0.000).术后视力与黄斑厚度有明显相关性:对于黄斑囊样水肿及黄斑前膜,术后视力提高行数和黄斑厚度呈负相关(r=-0.866,P=0.001),对于黄斑萎缩,两者呈正相关(r=0.928,P=0.000).2眼在白内障术后出现前囊膜收缩,2眼出现继发性高眼压,给予前囊膜放射状切开、药物控制眼压平稳后,视力提高且长期趋于稳定.结论 超声乳化白内障吸出联合人工晶状体植入术可以提高患者视力,是治疗视网膜色素变性合并白内障安全有效的方法.     

不同角膜曲率白内障患者三种人工晶状体屈光度计算公式的准确性比较

目的　探讨Barrett UniversalⅡ、Haigis和Olsen三种公式在不同角膜曲率的白内障患者人工晶状体度数计算中的准确性。方法　前瞻性临床研究。选取2020年1月至2021年10月收治于南京同仁医院眼科中心的86例（86眼）白内障患者作为研究对象，根据患眼角膜曲率不同分为3组，分别为A组26例，角膜曲率为>42~44 D；B组28例，角膜曲率为>44~46 D；C组32例，角膜曲率>46 D，比较3组患者一般资料；收集患眼术前分别依据Barrett UniversalⅡ、Haigis和Olsen公式计算的预留屈光度和术后3个月患者的实际屈光度，计算并比较各个公式的平均屈光误差，分析平均屈光误差在不同屈光域的占比；采用Pearson相关分析角膜曲率分别与三种计算公式获得的平均屈光误差之间的相关性。结果　3组患者间性别、年龄、视力、病程及术前眼压、眼轴长度和前房深度相比，差异均无统计学意义（均为P>0.05）。依据Barrett UniversalⅡ、Haigis、Olsen三种公式计算后患眼的屈光误差A组、B组、C组3组组间比较时，差异均无统计学意义（均为P>0.05）；依据Haigis、Olsen公式计算的患眼屈光误差A组、B组、C组组内均高于依据Barrett UniversalⅡ公式计算的患眼屈光误差，差异均有统计学意义（P<0.05）。依据Barrett Universal Ⅱ公式计算后屈光误差≤0.50 D 的患眼占比显著高于依据Haigis、Olsen公式计算后患眼的占比，差异均有统计学意义（均为P<0.05）。Pearson相关分析结果显示，依据Barrett UniversalⅡ、Haigis和Olsen公式计算的患眼屈光误差与角膜曲率均无明显相关性（均为P>0.05）。结论　依据Barrett UniversalⅡ、Haigis和Olsen三种公式计算的人工晶状体度数在不同角膜曲率的白内障患者中都较为准确，Barrett UniversalⅡ公式的准确率更高。