Accuracy of axial length measurements from immersion B-scan ultrasonography in highly myopic eyes

AIM:To evaluate the accuracy of axial length (AL) measurements obtained from immersion B-scan ultrasonography (immersion B-scan) for intraocular lens (IOL) power calculation in patients with high myopia and cataracts.METHODS:Immersion B-scan, contact A-scan ultrasonography (contact A-scan), and the IOLMaster were used to preoperatively measure the AL in 102 eyes from 102 patients who underwent phacoemulsification and IOL implantation. Patients were divided into two groups according to the AL:one containing patients with 22 mm≤AL<26 mm(group A) and the other containing patients with AL≥26 mm (group B). The mean error (ME) was calculated from the difference between the AL measurement methods predicted refractive error and the actual postoperative refractive error.RESULTS:In group A, ALs measured by immersion B-scan (23.48±1.15) didn’t differ significantly from those measured by the IOLMaster (23.52±1.17) or from those by contact A-scan (23.38±1.20). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.090±0.397 D) didn’t differ significantly from those of IOLMaster (-0.095±0.411 D) and contact A-scan (-0.099±0.425 D). In group B, ALs measured by immersion B-scan (27.97±2.21 mm) didn’t differ significantly from those of the IOLMaster (27.86±2.18 mm), but longer than those measured by Contact A-scan (27.75±2.23 mm, P=0.009). In the same group, the standard deviation (SD) of the mean error (ME) of immersion B-scan (-0.635±0.157 D) didn’t differ significantly from those of the IOLMaster (-0.679±0.359 D), but differed significantly from those of contact A-scan (-0.953±1.713 D, P=0.028).CONCLUSION:Immersion B-scan exhibits measurement accuracy comparable to that of the IOLMaster, and is thus a good alternative in measuring AL in eyes with high myopia when the IOLMaster can’t be used, and it is more accurate than the contact A-scan.     

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 3wk to 4mo. 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.     

后巩膜葡萄肿深度与高度近视合并白内障患者术后屈光误差的关系

目的　研究后巩膜葡萄肿深度与高度近视合并白内障患者术后屈光误差的关系。方法　选取在我院行白内障超声乳化摘出联合人工晶状体植入术的高度近视合并白内障伴后巩膜葡萄肿的患者共56例（70眼）。术前B超测量后巩膜葡萄肿深度。术后2个月时测量患者屈光状态,计算平均绝对屈光误差值（mean absolute refractive error,MAE）,并将后巩膜葡萄肿深度与MAE进行Pearson相关分析。结果　预期屈光度为（-2.91±0.85）D,术后实际屈光度为（-2.63±1.15）D,MAE为（-0.74±0.56）D,实际屈光度与预期屈光度差异有统计学意义（t=-2.723,P=0.008）。本组患者后巩膜葡萄肿深度为0~6.27（2.13±1.45）mm,其中64眼能测出后巩膜葡萄肿深度;6眼无法测量其后巩膜葡萄肿深度。后巩膜葡萄肿深度与眼轴长度呈正相关关系（r=0.776,P=0.00）;后巩膜葡萄肿深度与MAE呈正相关关系（r=0.522,P=0.00）;MAE与眼轴长度呈正相关关系（r=0.540,P=0.00）。结论　随着高度近视后巩膜葡萄肿深度增加,术后屈光误差增大。     

Intraocular lens calculation after refractive surgery for myopia: Haigis-L formula

PURPOSE: To describe the Haigis-L formula for the calculation of intraocular lenses (IOLs) after refractive laser surgery for myopia based on current biometry and keratometry and present clinical results. SETTING: University Eye Hospital, Wuerzburg, Germany, and various clinics and private practices. METHODS: The basic concepts of the new algorithm were described and summarized. The Haigis formula was analyzed with respect to its usability for eyes after laser surgery for myopia and modified accordingly. Correction curves for IOLMaster keratometry were derived from previous studies. The new formula was checked using the postoperative results of 187 cataract procedures in which 32 IOL types were implanted by 57 surgeons. Input data were current IOLMaster biometry as follows: axial length (AL), anterior chamber depth (ACD), and keratometry (corneal radii) measurements. RESULTS: Before IOL surgery, the mean spherical equivalent was -7.60 diopters (D) +/- 3.90 (SD) (range -20.00 to -1.25 D); the mean AL, 27.02 +/- 2.01 mm (range 23.09 to 35.32 mm); the mean ACD, 3.52 +/- 0.36 mm (range 2.43 to 4.39 mm); and the mean of the measured corneal radii, 8.70 +/- 0.60 mm (range 7.28 to 10.96 mm). The mean arithmetic refractive prediction error was -0.04 +/- 0.70 D (range -2.30 to +2.40 D) and the median absolute error, 0.37 D (range +0.01 to +2.40 D). The percentages of correct refraction predictions within +/-2.00, +/-1.00, and +/-0.50 D were 98.4%, 84.0%, and 61.0%, respectively. CONCLUSIONS: The new formula would produce promising results in eyes without refractive history. Its refractive predictability fulfills the current criteria for normal eyes.     

Comparison of refractive outcomes using immersion ultrasound biometry and IOLMaster biometry

Background:  The IOLMaster determines axial length using partial coherence interferometry. This study was designed to compare the refractive outcomes of patients who had been measured preoperatively by both immersion ultrasound and IOLMaster biometry.
Methods:  Patients were recruited from those who had undergone cataract surgery during the preceding 12 months by one surgeon at The Queen Elizabeth Hospital (55 eyes from 55 patients). Each patient underwent measurement of axial length by immersion ultrasound and the IOLMaster. Target refraction was determined using an SRK-T formula and the amount that this differed postoperative refraction was calculated for immersion ultrasound and the IOLMaster. These results were then compared.
Results:  Eyes measured longer by the IOLMaster method compared with immersion ultrasound (23.37 ± 0.87 vs. 23.25 ± 0.90 mm, t  = 4.83; P  < 0.0001). However anterior chamber depth was the similar. Postoperatively, final refractive outcome was 0.01 ± 0.63 dioptres (D) more hypermetropic than the target refraction when using the IOLMaster compared with 0.25 ± 0.73 D more myopic when using immersion ultrasound ( t  = 3.83; P  < 0.0001). Seventy-five per cent of patients were within 0.5 D of target refraction and 93% were within 1.0 D when the IOLMaster was used, compared with 49% and 85% within 0.5 and 1.0 D respectively when using immersion ultrasound (χ² = 8.34; P  = 0.04).
Conclusions:  Biometry performed using the IOLMaster produces a more predictable refractive outcome than immersion ultrasound, with patients' spherical equivalent more likely to be closer to their target refraction.     

IOLMaster biometry: refractive results of 100 consecutive cases

AIMS: To study the refractive outcome of cataract surgery employing IOLMaster biometry data and to compare it with that of applanation ultrasonography in a prospective study of 100 eyes that underwent phacoemulsification with intraocular lens implantation. METHODS: The Holladay formula using IOLMaster data was employed for the prediction of implanted intraocular lenses (IOLs). One month after cataract surgery the refractive outcome was determined. Preoperative applanation ultrasonography data were used retrospectively to calculate the IOL prediction error. The two different biometry methods are compared. RESULTS: 100 patients, 75.42 (SD 7.58) years of age, underwent phacoemulsification with IOL implantation. The optical axial length obtained by the IOLMaster was significantly longer (p<0.001, Student's t test) than the axial length by applanation ultrasound, 23.36 (SD 0.85) mm v 22.89 (0.83) mm. The mean postoperative spherical equivalent was 0.00 (0.40) D and the mean prediction error -0.15 (0.38) D. The mean absolute prediction error was 0.29 (0.27) D. 96% of the eyes were within 1 D from the intended refraction and 93% achieved unaided visual acuity of 6/9 or better. The Holladay formula performed better than the SRK/T, SRK II, and Hoffer Q formulas. Applanation ultrasonography after optimisation of the surgeon factor yielded a greater absolute prediction error than the optimised IOLMaster biometry, 0.41 (0.38) D v 0.25 (0.27) D, with 93% of the eyes within 1 D from the predicted refraction. CONCLUSION: IOLMaster optical biometry improves the refractive results of selected cataract surgery patients and is more accurate than applanation ultrasound biometry.     

高度近视合并白内障超声乳化术后屈光误差分析

目的：研究影响高度近视眼合并白内障患者行超声乳化及人工晶状体植入术后屈光状态的原因。 方法：对30例38眼轴性高度近视合并白内障患者行超声乳化及人工晶状体植入术,术后3mo测量患者屈光状态,和预期屈光状态对比,进行统计学分析。 结果：患者38眼术前平均预期屈光度为-1.39±0.47D,术后实际屈光度平均值为-0.87±0.93D,两者屈光度平均差值为-0.67±0.74D,两者比较差异有显著意义（t=3.375,P=0.002）。其中术后偏远视的有25眼,占66%。屈光度绝对差值与角膜曲率低度相关（r=0.443）,与眼轴长高度正相关（r=0.909）,随眼轴长增长,绝对差值加大。眼轴长为26～＜29mm的术眼屈光度平均绝对差值为0.61±0.39D,眼轴长≥29mm的术眼屈光度平均绝对差值为1.37±0.84D,两者比较差异有显著意义（t=2.8601,P=0.005）。在绝对差值分布上,眼轴长为26～＜29mm的术眼中所有差值均＜2.00D;眼轴长≥29mm的术眼中6眼差值≥2.00D,占32%。 结论：影响高度近视眼合并白内障患者的术后屈光状态原因有多种,眼轴长是最重要的原因之一。     

IOL Master在硅油填充眼生物测量中的应用

目的评价IOL Master对硅油填充眼进行生物测量的准确性。方法前瞻性选取2008年1月至12月间在我院行硅油取出术的硅油填充眼患者29例（29只眼）,在术前、术后均用IOLMaster测量眼轴长度,并用A超测量术后的眼轴,对结果进行比较。结果有6只眼因晶状体混浊明显或不能固视而未能测得眼轴,其余患眼IOL Master测得的术前、术后眼轴长分别为（26.37±2.80）mm及（26.29±2.77）mm,差值为（-0.04±0.15）mm（-0.36～0.23mm）（P=0.239）,相关系数为0.999;A超测得的患眼术后眼轴长度为（26.06±2.80）mm,患眼术前IOL Master与术后A超测得眼轴长度的差值为（0.18±0.17）mm（-0.21～0.58mm）（P〈0.01）,相关系数为0.998;术后IOL Master与A超测得眼轴长度的差值为（-0.23±0.13）mm（-0.54～-0.05mm）（P〈0.01）,相关系数为0.999。结论 IOL Master光学生物测量法可对硅油填充眼进行准确可靠的生物测量。     

Refractive errors in high myopic eyes after phacovitrectomy for macular hole

AIM: To examine the refractive prediction error in high myopic eyes after phacovitrectomy. METHODS: This retrospective comparative case series included 91 eyes (18 high myopic eyes and 73 non-high myopic eyes) of 91 patients who underwent successful phacovitrectomy (phacoemulsification, intraocular lens implantation, and pars plana vitrectomy). The high myopic eyes were defined as the eye with more than 26.0 mm of axial length. The postoperative prediction error of mean error and mean absolute error were evaluated at 4mo postoperatively. Axial length and keratometry measurement were performed preoperatively and 4mo postoperatively using the IOL Master. RESULTS: The refractive outcome after phacovitrectomy showed significantly greater myopic shift in the high myopic eyes [-1.08±0.87 diopters (D)] than that in the non-high myopic eyes (-0.43±0.63 D, P=0.004). Axial length and keratometric value in the high myopic eyes were significantly increased (P=0.043, 0.037 respectively), whereas those in the non-high myopic group were not significantly increased (P=0.135, 0.347 respectively). The change of the axial length in the myopic eye (0.46±0.28 mm) was greater than that in the non-high myopic eye (0.11 ± 0.34 mm; P<0.001). CONCLUSION: High myopic eyes showed more myopic shift than non-high myopic eyes after phacovitrectomy. The cause of myopic shift in high myopic eyes seems to be attributed to actual elongation of the axial length in high myopia.     

Five-year results of refractive outcomes and vision-related quality of life after SMILE for the correction of high myopia

AIM: To evaluate the long-term visual, refractive outcomes and vision-related quality of life after small incision lenticule extraction (SMILE) for the correction of high myopia. METHODS: Thirty patients (60 eyes) with high myopia who underwent SMILE more than 5y were selected as the SMILE group. Another 30 high myopia patients (60 eyes) who had worn corrective spectacles for more than 5y were selected as the control group. In SMILE group, the postoperative follow-up time were 3, 6mo, 1 and 5y. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), and ocular axial length (AL) were analyzed. The Chinese version of the National Eye Institute Visual Function Questionnaire-25 (CHI-NEI-VFQ-25) was used to evaluate the vision-related quality of life in the SMILE group and the control group. RESULTS: In SMILE group, the mean preoperative SE was -7.29±0.87 D (range -6.00 to -9.125 D). At 5-year follow up, the efficacy index and safety index of SMILE were 1.09±0.18 and 1.19±0.12, respectively. Five years postoperatively, 44 eyes (73%) obtained a visual acuity of 20/20 or better. There were no eyes with CDVA loss of one or more Snellen lines. Forty-nine eyes (82%) and 57 eyes (95%) were within ±0.50 and ±1.00 D of attempted correction at 5-year follow-up, respectively. Forty-eight eyes (80%) had astigmatism <0.50 D at 5-year follow-up. The postoperative mean SE values at 3, 6mo, 1, and 5y were 0.11±0.44, 0.07±0.45, -0.02±0.41, and -0.15±0.46 D, respectively. No significant change was observed in the ocular AL from before operation to 5y postoperatively (26.08±0.96 mm vs 26.01±0.94 mm, P=0.068). Compared to the control group, the SMILE group showed a significantly higher total score on the CHI-NEI-VFQ-25 (90.14 vs 81.43, P<0.001). CONCLUSION: In the present study, in a long-term follow-up we demonstrate that correcting high myopia with SMILE is safe, effective, and predictable. Vision-related quality of life after SMILE is better in the SMILE group than in the control group who wore corrective spectacles.     

Axial length, vitreoretinal pathology, and anterior chamber depth can predict postoperative refractive outcomes in phacovitrectomy/silicone oil removal

AIM: To evaluate the postoperative refractive prediction error (PE) and determine the factors that affect the refractive outcomes of combined pars plana vitrectomy (PPV) or silicone oil removal (SOR) with cataract surgery. METHODS: The study is a retrospective, case-series study. Totally 301 eyes of 301 patients undergoing combined PPV/SOR with cataract surgery were enrolled. Eligible individuals were separated into four groups according to their preoperative diagnoses: silicone oil-filled eyes after PPV (group 1), epiretinal membrane (group 2), macular hole (group 3), and primary retinal detachment (RD; group 4). The variables affecting postoperative refractive outcomes were analyzed, including age, gender, preoperative best-corrected visual acuity (BCVA), axial length (AL), keratometry average, anterior chamber depth (ACD), intraocular tamponade, and vitreoretinal pathology. The outcome measurements include the mean refractive PE and the proportions of eyes with a PE within ±0.50 diopter (D) and ±1.00 D. RESULTS: For all patients, the mean PE was -0.04±1.17 D, and 50.17% of patients (eyes) had a PE within ±0.50 D. There was a significant difference in refractive outcomes among the four groups (P=0.028), with RD (group 4) showing the least favorable refractive outcome. In multivariate regression analysis, only AL, vitreoretinal pathology, and ACD were strongly associated with PE (all P<0.01). Univariate analysis revealed that longer eyes (AL>26 mm) and a deeper ACD were correlated with hyperopic PE, and shorter eyes (AL<26 mm) and a shallower ACD were correlated with myopic PE. CONCLUSION: RD patients have the least favorable refractive outcome. AL, vitreoretinal pathology, and ACD are strongly associated with PE in the combined surgery. These three factors affect refractive outcomes and thus can be used to predict a better postoperative refractive outcome in clinical practice.     

Wang-Koch优化眼轴SRK/T公式预测不同眼轴长度下高度近视眼合并白内障术后屈光度准确性的临床研究

目的初步探讨应用Wang-Koch优化眼轴SRK/T公式预测不同眼轴长度下高度近视眼合并白内障患者术后屈光度的准确性。 方法收集2019年1月至2019年12月于成都爱尔眼科医院行白内障超声乳化联合人工晶状体植入术的59例(63只眼)高度近视眼合并白内障患者。其中，男性30例(33只眼)，女性29例(30只眼)；年龄44~73岁，平均年龄(59.6±8.8)岁。采用IOL Master 700测量患者术前的角膜曲率、眼轴、前房深度及晶状体厚度。根据患者眼轴长度的大小分为A组、B组及C组。A组为27 mm≤眼轴<28.00 mm，B组为28.00 mm≤眼轴<30.00 mm，C组为眼轴≥30.00 mm。个性化选取适宜的预留屈光度，包括SRK/T、Wang-Koch优化眼轴SRK/T和Barrett Universal Ⅱ三种公式的预留屈光度。术后1个月随访，测量患者实际的屈光度，计算三种公式预留屈光度与术后实际屈光度的差值及平均绝对屈光误差，比较不同公式及分组下人工晶状体屈光度预测的准确性。采用Shapiro-Wilk正态性检验分析屈光度误差；当符合正态分布时以均数±标准差表示，采用单因素方差分析进行组间比较；反之，采用中位数和上下四分位数表示，采用非参数检验进行组间比较。采用眼数和百分比描述不同屈光阈所占的百分比，采用卡方检验进行组间比较。采用Spearman相关系数和线性回归分析评估眼轴与平均绝对屈光误差间的相关性。 结果59例(63只眼)患者中，SRK/T、Wang-Koch优化眼轴SRK/T及Barrett Universal Ⅱ三种公式的平均绝对屈光误差分别为0.57(0.32，0.98)D、0.32(0.17，0.61)D及0.34(0.17，0.66)D。后两者的平均绝对屈光误差明显小于前者。经单因素方差分析，两者比较的差异有统计学意义(Z＝-3.77，-4.28；P<0.05)。术后屈光误差在±0.50 D和±1.00 D范围内所占百分比中，Wang-Koch优化眼轴SRK/T公式最高，分别为69.8%和98.4%。A组与B组内三种公式平均绝对屈光误差的比较，差异无统计学意义(Z＝-0.28，-0.97；P>0.05)。C组SRK/T公式预测的平均绝对屈光误差最大。经单因素方差分析，SRK/T、Wang-Koch优化眼轴SRK/T及Barrett Universal Ⅱ三种公式预测屈光度的比较，差异有统计学意义(Z＝-3.22，-3.29；P<0.05)。使用SRK/T公式时，平均绝对屈光误差与眼轴相关。经Spearman相关性分析，其差异有统计学意义(r＝0.521，P<0.05)。使用Wang-Koch优化眼轴SRK/T公式及Barrett Universal Ⅱ公式时，平均绝对屈光误差与眼轴不相关。经Spearman相关性分析，其差异无统计学意义(r＝0.249，0.228；P>0.05)。SRK/T的平均绝对屈光误差与眼轴的一元回归方程为Y＝-3.606+0.146X。经Spearman相关性分析，其差异无统计学意义(r＝0.249，P>0.05)。 结论对高度近视眼患者进行人工晶状体屈光度计算时，SRK/T、Wang-Koch优化眼轴SRK/T和Barrett Universal Ⅱ公式都是相对准确的。但当患者眼轴≥30 mm时，Wang-Koch优化眼轴SRK/T公式和Barrett Universal Ⅱ公式的预测屈光误差更小。     

不同测量仪器和不同IOL屈光度计算公式对硅油填充合并白内障眼IOL屈光度测算的比较

背景 玻璃体切割联合硅油填充眼易诱发和加速白内障的形成,白内障联合硅油取出术前人工晶状体(IOL)屈光度的准确测算是术眼获得术后良好视觉质量的关键. 目的 研究不同仪器和不同IOL计算公式在硅油填充合并白内障眼行白内障摘出联合IOL植入术前IOL屈光度测算的差异,并测算术前预测IOL屈光度与术后术眼屈光度的误差,为临床相关工作提供参考依据. 方法 采用前瞻性非随机对照的研究方法,于2011年8月至2013年10月在苏州大学附属第二医院连续纳入玻璃体切 割术后硅油填充合并白内障者36例36眼,患眼均于硅油乳化后4个月～2年拟行白内障超声乳化+IOL植入+硅油取出术,术前分别用IOLMaster及A型超声联合手动角膜曲率计(MK)测量术眼眼轴长度(AL)、角膜曲率(CC)和前房深度(ACD)等生物学参数,分别采用SRK-Ⅱ、SRK/T、Hoffer Q、Holladay 1和Haigis计算公式和预留的屈光度计算拟植入的IOL屈光度,分析和比较IOLMaster及A型超声联合MK用上述计算公式测算的IOL理论屈光度值与术后术眼实际屈光度值的平均预测误差(MPE)和平均绝对屈光误差(MAE). 结果 A型超声+MK和IOLMaster测得的AL分别为(25.21±1.02) mm和(25.43±0.90) mm,ACD分别为(3.07±0.62) mm和(3.22±0.38)mm,A型超声+MK测量的AL和ACD值明显小于IOLMaster测量结果,差异均有统计学意义(均P=0.000).IOLMaster与A型超声+MK测得的CC分别为(44.58±1.57)D和(44.56±1.62)D,差异无统计学意义(P=0.568).用IOLMaster测量时,SRK/T公式的MAE明显小于SRK-Ⅱ、Hoffer Q、Holladay 1和Haigis公式的MAE,差异均有统计学差异(P=0.017、0.009、0.012、0.001);Haigis公式的MAE明显大于SRK-Ⅱ、HofferQ和Holladay 1公式的MAE,差异均有统计学意义(P=0.026、0.035、0.021).用A型超声+MK测量时,Haigis公式的MAE明显大于与SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1公式的MAE,差异均有统计学意义(P=0.007、0.004、0.018、0.006).用SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1公式计算时,IOLMaster与A型超声+MK间测量的MAE≤1.0D眼数比较差异均无统计学意义(x2=0.107、2.250、0.845、0.084,均P＞0.05);用Haigis公式计算时,IOLMaster测量的MAE≤1.0D眼数明显多于A型超声+MK测量结果,差异有统计学意义(x2=4.431,P=0.035). 结论 使用IOLMaster时SRK/T公式测算的IOL屈光度准确性最高,用A型超声+MK测量时推荐使用SRK-Ⅱ、SRK/T、Hoffer Q和Holladay 1测算公式.     

Biometry data from caucasian and african-american cataractous pediatric eyes

PURPOSE: To report the biometry data of pediatric cataractous eyes (randomly selected single eye in bilateral cases; cataractous eye in unilateral cases) and to compare the biometry data of the unilateral cataractous eye with the data of the corresponding noncataractous fellow eye. METHODS: The study was a chart review/analysis of immersion A-scan biometry measurements, excluding traumatic cataract or lens subluxation. RESULTS: Three hundred ten eyes were examined at surgery. The mean age was 45.30 +/- 48.10 months; globe axial length (AL), 20.52 +/- 2.87 mm; anterior chamber depth (ACD), 3.29 +/- 0.60 mm; and lens thickness (LT), 3.62 +/- 0.86 mm. During the first 6 months of life, AL increased 0.62 mm/mo, 0.19 mm/mo from 6 to 18 months, and 0.01 mm/mo during 18 months to 18 years of age. The girls had shorter ALs than did the boys (P = 0.090), and the African-American subjects had longer ALs than did the Caucasians (P < 0.001). Eyes with unilateral cataract had shorter ALs than those with bilateral cataracts before 60 months of age, but had longer ALs than the eyes with bilateral cataracts after 60 months of age. Eyes of the female subjects had shallower ACDs than those of male subjects (P = 0.026). Eyes with unilateral cataract had shallower ACDs than those of eyes with bilateral cataracts (P = 0.001). In the children >5 years of age, LT was significantly greater in eyes with unilateral cataract than in those with bilateral cataract. AL of the unilateral cataractous eye was significantly shorter than that of the fellow noncataractous eye before 6 months of age (P = 0.001). CONCLUSIONS: This study begins to lay the groundwork for calculating pediatric IOL power in cataractous eyes by using pediatric ocular measurements.     

Refractive errors,axial ocular dimensions,and age-related cataracts: the Tanjong Pagar survey

PURPOSE: To describe the relationship of refractive errors and axial ocular dimensions and age-related cataract. METHODS: Population-based, cross-sectional survey of ocular diseases among Chinese men and women aged 40 to 81 years (n = 1232) living in the Tanjong Pagar district in Singapore. As part of the examination, refraction and corneal curvature were determined with an autorefractor, with refraction further refined subjectively. Ocular dimensions, including axial length, anterior chamber depth, lens thickness, and vitreous chamber depth, were measured with an A-mode ultrasound device. Lens opacity was graded clinically according to the Lens Opacity Classification System (LOCS) III system. Refraction, biometry, and cataract data on right (n = 989) and left (n = 995) eyes were analyzed separately. RESULTS: In analyses controlling for age, gender, education, diabetes, and cigarette smoking, nuclear cataract was associated with myopia (-1.35 D vs. -0.11 D, P < 0.001, comparing right eyes with and without nuclear cataract), but not with any specific biometric component. Cortical cataract was associated with thinner lenses (4.67 mm vs. 4.79 mm, P = 0.001, comparing right eyes with and without cortical cataract), but not with refraction and other biometric components. Posterior subcapsular cataract was associated with myopia (-1.80 D vs. -0.39 D, P < 0.001, comparing right eyes with and without posterior subcapsular cataract), deeper anterior chamber (3.00 mm vs. 2.89 mm, P = 0.02), thinner lens (4.62 mm vs. 4.77 mm, P = 0.001), and longer vitreous chamber (15.78 mm vs. 15.57 mm, P = 0.09), but not with overall axial length and corneal curvature. Adjustment for vitreous chamber depth attenuated the association between posterior subcapsular cataract and myopia by 65.5%, but did not substantially change the association between nuclear cataract and myopia. CONCLUSIONS: These population-based data support the associations between nuclear and posterior subcapsular cataracts and myopia reported in previous studies. Posterior subcapsular cataract is also associated with deeper anterior chamber, thinner lens, and longer vitreous chamber, with vitreous chamber depth explaining most of the association between posterior subcapsular cataract and myopia.     

Prevalence of corneal astigmatism before cataract surgery

The purpose of this study was to describe and analyze the prevalence and pattern of corneal astigmatism in cataract surgery candidates. In a prospective cross-sectional study, preoperative demographics, and keratometric and refractive values of cataract surgery candidates were collected from January 2013 to December 2014. Axial length (AL) and flat and steep keratometry measurements were optically measured by a partial coherence interferometry device (IOLMaster). This study consisted of 2156 eyes of 1317 patients with a mean age of 64.92 ± 11.48 (SD) (30–88 years). The mean of AL was 23.33 ± 1.37 mm, and the mean of corneal astigmatism was 1.12 ± 1.10 diopter (D) (range 0.0–7.00), in all patients. Furthermore, the mean of flat and steep keratometry were 43.70 ± 1.70 and 44.83 ± 1.79 D, respectively. Corneal astigmatism was 1.50 D or less in 1590 eyes (73.7 %), more than 1.50 D in 566 eyes (26.2 %), 3.00 D or more in 161 eyes (7.4 %), WTR in 796 eyes (36.9 %), ATR in 1010 eyes (46.8 %), and oblique in 350 eyes (16.2 %). ATR astigmatism axis significantly increased with the increase in age. Corneal astigmatism of most cataract surgery candidates fell between 0.50 and 1.50 D. The results of our study however is confined to our demographics might provide useful data for cataract patients, surgeons, and intraocular lens manufacturers for different purposes.     

Agreement analysis of LENSTAR with other techniques of biometry

Purpose

To assess the agreement of the optical low-coherence reflectometry (OLCR) device LENSTAR LS900 with partial coherence interferometry (PCI) device IOLMaster and applanation and immersion ultrasound biometry.

Methods

We conducted the study at the Ophthalmology Clinic, University of Malaya Medical Center, Malaysia. Phakic eyes of 76 consecutive cataract patients were measured using four different methods: IOLMaster, LENSTAR and A-scan applanation and immersion ultrasound biometry. We assessed the method agreement in the LENSTAR-IOLMaster, LENSTAR-applanation, and LENSTAR-immersion comparisons for axial length (AL) and intraocular lens (IOL) power using Bland–Altman plots. For average K, we compared LENSTAR with IOLMaster and the TOPCON KR-8100 autorefractor-keratometer. SRK/T formula was used to compute IOL power, with emmetropia as the target refractive outcome.

Results

For all the variables studied, LENSTAR agreement with IOLMaster is strongest, followed by those with immersion and applanation. For the LENSTAR-IOLMaster comparison, the estimated proportion of differences falling within 0.33 mm from zero AL and within 1D from zero IOL power is 100%. The estimated proportion of differences falling within 0.5 D from zero average K is almost 100% in the LENSTAR-IOLMaster comparison but 88% in the LENSTAR-TOPCON comparison. The proportion of differences falling within 0.10 mm (AL) and within 1D (IOL power) in the LENSTAR-IOLMaster comparison has practically significant discrepancy with that of LENSTAR-applanation and LENSTAR-immersion comparisons.

Conclusions

In phakic eyes of cataract patients, measurements of AL, average K, and IOL power calculated using the SRK/T formula from LENSTAR are biometrically equivalent to those from IOLMaster, but not with those from applanation and immersion ultrasound biometry.     

浅前房对白内障超声乳化联合人工晶状体植入术后屈光状态的影响

目的 探讨中央浅前房对白内障手术后屈光状态的影响。设计 前瞻性病例系列。研究对象 2016年12月至2017年6月在北京同仁医院眼科进行白内障超声乳化联合人工晶状体植入手术且中央前房深度<2.0 mm的患者61例（61眼）为研究组,同期进行手术的中央前房深度≥2.0 mm的患者61例（61眼）为对照组。方法 分别测量浅前房及对照组患者手术眼的眼轴长度、手术前后的前房深度及术后的屈光偏差度数。术后3个月比较两组术眼手术前后的前房深度变化、术后屈光偏差,并对前房深度与眼轴长度进行相关性分析。主要指标 眼轴长度、手术前后前房深度、术后屈光偏差度数。结果 浅前房组术后前房深度变化（1.31±0.14） mm,对照组为（0.79±0.27） mm（P=0.024）。浅前房组及对照组手术眼的前房深度与眼轴长度均为正相关（P=0.001和0.000）。术后3个月浅前房组的目标屈光偏差（0.78±0.16）D,呈远视漂移;对照组目标屈光偏差（-0.37±0.21）D,呈近视漂移。浅前房组较对照组目标屈光偏差的绝对值大（P=0.032）。结论 浅前房白内障患者术后更容易发生远视漂移,在术前进行屈光度数预留设计时要考虑这个可能,作出相应调整。     

放射状角膜切开术后人工晶状体屈光度计算的临床观察

目的：评估Barrett True K公式应用于放射状角膜切开术(RK)术后的白内障患者的屈光准确性。

方法：选取2017-02/2019-02在我院确诊为RK屈光手术后的白内障患者22例42眼,术前分别用两种方法计算人工晶状体屈光度：(1)选取术眼角膜中央直径3mm区域最小的前表面K值,应用SRK/T公式计算,目标屈光度设为-1.0D;(2)用Barrett True K在线计算公式,选择RK术后模式,目标屈光度设为-1.0D。术后3mo检查术眼屈光状态,对比两种方法计算的屈光误差。

结果：术后3mo,Barrett公式法屈光误差为0.61(-0.37, 0.88)D,明显低于传统公式法的0.35(-0.25, 0.63)D(P<0.05); 屈光误差绝对值比较无差异(P>0.05)。传统公式法屈光误差在±0.5、±1.0、±2.0D的范围的分别占21%、45%、90%,Barrett公式法屈光误差在±0.5、±1.0、±2.0D的范围的分别占31%、74%、100%(P<0.05)。

结论：Barrett True K在线公式应用于RK术后的白内障患者可达到较满意的屈光状态。     

高度近视白内障患者眼轴测量方法的探讨

目的:探讨高度近视白内障患者眼轴测量方法,提高检查的准确性。方法:对103例(168只眼)高度近视合并白内障患者,用A/B超测量仪(法国光太公司生产的A/B超测量仪和加拿大OTI公司生产的A/B超测量仪)和光学相干生物测量仪(德国生产的IOLMASTER)多种仪器对比测量。结合B超了解后巩膜葡萄肿的位置,对后巩膜葡萄肿位于黄斑区者,调整对准葡萄肿位置诱导出现标准波形进行测量。对后巩膜葡萄肿位于黄斑区之外者,避开葡萄肿位置,诱导出现标准波形。用多种仪器对照测量,对照标准波形(图1)取三次标准波形的均值作为眼轴数据计算人工晶状体度数,并对患者手术后屈光度进行分析。结果:本组患者的后巩膜葡萄肿发生率为76.19%。患者术后复查,平均绝对屈光误差≤±1D为100%。结论:对高度近视白内障患者,特别有后巩膜葡萄肿患者,采取A、B超结合测量,多种仪器对照测量,观察获取标准波形的均值等综合方法获取准确的眼轴数据。