Evaluation of corneal endothelium following cataract surgery in diabetic patients

PURPOSE: The aim of this study was to evaluate the influence of cataract surgery on the condition of corneal endothelium, in diabetic patients. MATERIAL AND METHODS: We examined 103 patients (103 eyes) after cataract surgery (64 women and 39 men), at the age between 49 and 89. In our study we didn't involve any patients with intra or post-surgery complications. Using Specular Microscope SP-1000 corneal endothelium was examined before cataract surgery and in the long-term follow-up: 7, 30 and 90 days after surgery. The patients were divided into two groups: suffering from diabetes (54) and matched control group--non-diabetic patients with cataract (49). The same patients were also divided depending on the type of surgical technique: phacoemulsification (42) or extracapsular cataract extraction (61). RESULTS: The mean percent loss of corneal endothelium cells, due to surgery in diabetic patients was: 11.31% after 7 days, 13.99% after 30 and 15.38% after 90 days. In the control group: 5.45% after 7 days, 8.66% after 30 and 11.33% after 90 days. The mean percent loss of corneal endothelium cells after phacoemulsification was: 10.10% after 7 days, 13.21% after 30 and 15.87% after 90 days; after extra-capsular cataract extraction: 6.84% after 7 days, 9.71% after 30 and 11.48% after 90 days. Differences between mean value of corneal endothelial cells in diabetic patients compared with control group, were statistically essential 7 and 30 days after cataract surgery, and near such assessment 90 days after surgery. There were no statistically essential differences between endothelial cells density in both operated groups, in relation to type of operation (phacoemulsification and extra-capsular cataract extraction). CONCLUSIONS: Above results are the evidence, that cataract surgery is a big trauma for cornea, especially for its endothelium. The operation is mainly dangerous for patients suffering from diabetes. The surgeon should be aware of the above threat during cataract surgery in diabetic patients, and therefore should express high level of caution, irrespective of the technique of operation.     

Effect of cataract surgery on the corneal endothelium: modern phacoemulsification compared with extracapsular cataract surgery

PURPOSE: To investigate whether modern phacoemulsification surgery results in more damage to the corneal endothelium than extracapsular cataract extraction (ECCE), and to examine which preoperative, operative, and postoperative factors influence the effect of cataract surgery on the endothelium. DESIGN: Randomized controlled trial. PARTICIPANTS: Five hundred patients 40 years or older were randomized into 2 groups (ECCE, 249; phacoemulsification, 251). METHODS: Central corneal endothelial cell counts, coefficient of variation of cell size, and hexagonality were assessed before surgery and up to 1 year postoperatively. MAIN OUTCOME MEASURE: Endothelial cell count. RESULTS: Four hundred thirty-three patients completed the trial. The initial preoperative mean cell count for the entire sample was 2481 (standard error [SE]: 18.6), reduced at 1 year postoperatively to 2239 (SE: 23.5). An average 10% reduction in cell count was recorded by 1 year postoperatively. There was no such change in hexagonality or in the coefficient of variation. There was no significant difference in overall percentage cell loss between the 2 treatment groups. Factors associated with excessive cell loss (> or =15% by 1 year) were a hard cataract (odds ratio [OR]: 2.1, 95% confidence limits: 1.1-4.1; P = 0.036), age (OR: 1.04, P = 0.005), and capsule or vitreous loss at surgery (OR: 2.38, P = 0.106). Phacoemulsification carried a significantly higher risk (OR: 3.7, P = 0.045) of severe cell loss in the 45 patients with hard cataracts relative to ECCE (52.6% vs. 23.1%; chi-square test, P = 0.041), with both procedures achieving similar postoperative visual acuity outcomes. CONCLUSIONS: No significant difference in overall corneal endothelial cell loss was found between these 2 operative techniques. The increased risk of severe cell loss with phacoemulsification in patients with hard cataracts suggests that phacoemulsification may not be the optimal procedure in these cases, and that ECCE should be preferred.     

白内障手术中反向超声乳化对角膜内皮的保护作用

目的：研究反向超声乳化针头斜面朝向后方(反向超声乳化)对角膜内皮的保护作用。

方法：对60例60眼老年性白内障患者,随机分成两组,常规超声组和反向超声组,术前常规进行全身及眼科专科检查,并详细记录每位患者的性别、年龄、核硬度分级、角膜内皮计数、眼压、前房深度、轴深等数据; 两组患者分别采用常规超声乳化和反向超声乳化的方式完成超声乳化和折叠式人工晶状体的植入,记录术中超声乳化时所使用的平均超声能量和有效超声时间,最终可计算出平均复合超声能量(平均超声能量×有效超声时间),同时记录术中出现的手术并发症等情况; 术后第3d对两组患者进行眼压和角膜内皮细胞计数检查。

结果：经统计,术前两组患者基本情况无明显统计学差异(P>0.05)。两组患者分别经不同的超声乳化方式治疗后,两组患者在手术中所接受的平均复合超声能量和术后第3d的眼压无明显统计学差异(t=-0.95,P=0.924>0.05; t=0.34,P=0.735>0.05)。而两组患者术后第3d的角膜内皮细胞丢失数量比较,有明显统计学差异(t=-9.89,P<0.01)。

结论：反向超声乳化较常规方式超声乳化有明显的保护角膜内皮细胞、减少损伤的作用,值得临床工作中推广。     

Standard coaxial phaco microincision cataract surgery: a corneal endothelium study

To assess whether the new microincision cataract surgery (MICS) induces less endothelium damages than the standard coaxial phacoemulsification. · METHODS: Two hundred consecutive patients affected by age-related cataract were randomly assigned to undergo phacoemulsification using either standard coaxial phaco (SCP) or MICS. Central cornea and 12 o'clock endothelial cell count, cell size variation coefficient, percentage of hexagonality and central cornea thickness were measured before and up to one year after surgery. · RESULTS: One hundred and seventy-three patients completed the trial. At the one-year follow-up visit, the loss of endothelium cells was 6.5204% in the MICS group and 8.726% in the SCP group (P <0.00005). There were no significant differences between the two groups in terms of coefficient of variation in cell size, percentage of hexagonal cells, corneal thickness the day after surgery and variation of endothelial cell density measured both at the incision site and at the central cornea. In patients with hard cataracts, the increase in endothelial cell density loss was higher indepen- dently of the procedure. · CONCLUSION: MICS induces a significant lower endothelial cell density loss than SCP.     

Response of corneal hysteresis and central corneal thickness following clear corneal cataract surgery

Purpose: To evaluate the effect of routine phacoemulsification in corneal viscoelastic properties determined by corneal hysteresis (CH) and central corneal thickness (CCT) and to explore the impact of phaco energy on the above parameters. Methods: Forty‐one eyes of 41 patients undergoing cataract surgery were enrolled in this prospective study. CH and CCT were measured preoperatively, 1 day and 1 week postoperatively. CCT measurement was performed using a non‐contact optical pachymeter followed by ocular response analyzer (ORA) examination. Intraoperatively ultrasound time, average phaco power and effective phaco time (EPT) were recorded. Results: Mean CH was 10.05 ± 1.86 mmHg preoperatively, 8.25 ± 1.85 mmHg 1 day and 9.12 ± 1.37 mmHg 1 week postoperatively (p < 0.001). The mean CCT was 534 ± 37.33 μm preoperatively, 592.22 ± 46.34 μm 1 day and 563.21 ± 49.84 μm 1 week postoperatively (p < 0.001). CCT and CH were statistically significantly correlated preoperatively (p = 0.01, r = 0.396). This correlation was not sustained on the first postoperative day (p = 0.094, r = 0.265) and was re‐established 1 week postoperatively (p = 0.002, r = 0.568). On the first postoperative day, the CCT increase was positively correlated with EPT (p = 0.009, r = 0.404), which was not found between CH change and EPT. Conclusion: Structural corneal alterations following cataract surgery resulted in a statistical change in CH and CCT. These two parameters responded in a different manner that clearly demarcates their different nature. On the first postoperative day, CCT increase was correlated at a statistically significant level with intraoperative EPT. This correlation was not found with CH reduction. Other factors, besides cornea oedema or phacoemulsification energy, could be responsible for this CH modification.     

Cell density of the corneal endothelium in human fetus by flat preparation

PURPOSE: To count the number of the corneal endothelial cells per unit of tissue area in 25 human fetal eyes ranging from 12-40 weeks of gestation with the histologic method. METHODS: The endothelium including Descemet's membrane was stained with hematoxylin-eosin by the flat preparation method. We photographed the endothelium using light microscopy. The number of nuclei was counted on each photograph. A calibrated micrometer was photographed with the light microscopy, and this was used to measure the number of corneal endothelial cells per square millimeter. RESULTS: The prenatal endothelial cell density of the human cornea decreases rapidly from 14,095 cells/mm2 (12 weeks of gestation) to 6,820 cells/mm2 (40 weeks of gestation). CONCLUSION: The estimate of the endothelial cell density at 12 weeks of gestation is twofold higher than the estimate at 40 weeks of gestation.     

Evaluation of corneal endothelium after pediatric cataract surgery in children and adolescents

PURPOSE: to evaluate the effects of cataract extraction and lens implantation on corneal endothelium morphology. MATERIAL AND METHODS: In 21 eyes of 14 children with congenital or developmental cataract, corneal endothelium was studied. Patient age was 9 to 19 years (mean 12.9 years). In all eyes extracapsular cataract extraction (ECCE) with PMMA intraocular lens implantation was performed, without primary posterior capsulotomy or anterior vitrectomy. Lens wearers, patients with traumatic cataract or external eye diseases and ocular surgery in history were excluded. The endothelium was imaged by non-contact microscope Topcon SP-2000P. This examination was done preoperatively and 1 month, 6 months and 1 year postoperatively. Corneal thickness (T), corneal endothelial density (ECD) and mean cell area (AVG) of endothelial cells were examined. RESULTS: Mean corneal thickness was 0.55 mm after 1 month, 0.54 mm after 6 months and 0.54 mm after 12 months. The mean preoperative endothelial cell density was 3231.1 cells/mm2. ECD after 1.6 and 12 months was 2874.3; 2639.2 and 2479.9 cells/mm2 respectively. Mean endothelial cell loss was 10.94% after 1 month, 17.85% after 6 months and 22.68% after 12 months. AVG before operation was 315.8 mm2, after 1 month 355.8 mm2, after 6 months 382.4 mm2 and 399.5 mm2 after 12 months. CONCLUSIONS: Changes in corneal endothelium morphology had no effect on transparency of the cornea.     

白内障手术切口大小对角膜内皮的影响

为了解白内障手术切口大小与术后角膜内皮变化的关系。方法：应用非接触式角膜内皮显微镜对三组不同大小切口的白内障术后角膜内皮计数和形态学变化进行观察，它们的切口分别为第一组（大切口）１０～１２ｍｍ，第二组（中切口）５．５～６．５ｍｍ，第三组（小切口）３．２ｍｍ，结果：三组术后角膜内皮损失率分别是：第一组１４．６５±８．１９％，第二组１４．５５±９．６３％，第三组１２．６５±９．７２％，三者无显著性差异（ｘ２检验，Ｐ＞０．０５）；三组术后形态变化相同：早期表现内皮细胞脱落和肿胀、伸长变形修复，三月以上形态改变趋于稳定。结论：白内障手术切口大小与角膜细胞内皮变化无直接关系，内皮的变化主要与操作技巧和术后前房反应的轻重有关。     

玻璃体视网膜手术后角膜内皮细胞的形态学改变

目的：观察不同术式的玻璃体视网膜手术（vitreoretinal surgery,VRS)后角膜内皮细胞的形态学改变。方法：采用Topcon SP9000型非接触型角膜内皮显微镜对66例66眼行玻璃体视网膜手术前，术后1、3个月角膜内皮细胞的4项形态学定量指标（角膜内皮细胞密度，角膜内皮细胞平均面积、内皮细胞面积变异系数，六角形细胞比率）进行观测，结果：VR术未摘除晶状体组，手术前后角膜内皮4项形态学定量指标相比较，差异均无显著性（P＞0．05），晶状体玻璃体视网膜联合手术（lenticular vitreoretinal surgery,LVRS)组术后角膜内皮细胞密度，六角形细胞比率明显降低，平均细胞面积和变异系数明显增大，与术前相比差异有极显著性（P＜0．001）。结论：LVR术损伤角膜内皮，VR术未摘除晶状体，对角膜内皮无显著影响，为减少手术对角膜内皮的损伤，术前检查角膜内皮，选择合适的手术方式，提高手术技巧，积极控制炎症是十分必要的。     

Influence of cataract surgery on corneal endothelial cell density estimation

PURPOSE: To assess the effect of cataract surgery on semiautomated human corneal endothelial cell density (ECD) estimation using noncontact specular microscopy. METHODS: In this prospective clinical study, 62 consecutive patients undergoing cataract surgery were studied. To evaluate possible variations of accuracy and agreement under clinical circumstances, the corneal ECD was determined before and after cataract surgery. The parameter ECD (cells/mm) in the central and paracentral cornea was consecutively determined with 2 algorithms available in a noncontact specular microscope [fixed-frame method (FFM) and automatic center method (ACM)]. The postoperative evaluation was performed at 1 day, after 4 weeks, and after 6 months. The accuracy, the relative error, and the 95% limits of agreement (LoA) were determined for both counting methods. RESULTS: The overall group-averaged accuracy was -19.4 cells/mm (0.86%) centrally and -17.3 cells/mm (0.76%) paracentrally. The LoA (95% CI) were within 234 cells/mm (10.4%) and 250 cells/mm (10.9%), respectively. After cataract surgery, a slight decrease in accuracy was noted in the central (2.09%) and paracentral areas (1.76%). The relative error increased from 3.66% to 6.02% centrally and from 4.96% to 6.55% paracentrally. The LoA (95% CI) increased from +/-194 cells/mm to +/-304 cells/mm centrally and from +/-275 cells/mm to +/-322 cells/mm paracentrally. In the later postoperative period, endothelial stabilization improved the accuracy and agreement in ECD estimation. CONCLUSIONS: The estimation of ECD after cataract surgery employing current algorithms was achieved with a clinically acceptable level of accuracy and agreement. However, the analysis of images in the early postoperative period as well as paracentral corneal areas revealed larger variabilities. This revealed that the FFM and ACM counting methods cannot be used interchangeably under all circumstances. The ACM seemed preferable when only low-quality images were available and permitted determination of additional qualitative endothelial cell parameters.     

Modelling of changes in the corneal endothelium after cataract surgery and penetrating keratoplasty.

Long term changes in endothelial cell density were monitored in three groups of patients after surgery. One group underwent uncomplicated cataract surgery, one group complicated cataract surgery which eventually progressed to corneal decompensation, and one group penetrating keratoplasty. A mathematical model is presented which describes endothelial cell loss after surgery as an exponential decay process towards an asymptote with constant rate of cell loss over time. When fitted to the data from the three groups there is excellent agreement in each case. Discriminant analysis techniques were applied to model predictions to assess the likelihood of late corneal decompensation after surgery. From measurements of endothelial cell density before and after surgery we were able to correctly assign patients undergoing cataract surgery to decompensation or non-decompensation groups in 85.7% and 92.7% of cases respectively.     

Cellular density of normal corneal endothelium

With the aid of the specular microscope photographs were made of the endothelium of 72 subjects, 41 men and 31 women, aged from 24 to 86 years. The number of endothelial cells was counted by projecting the photographs and counting the cells in a given area. The average variation per eye was 4.9% with a standard deviation of 3.7. A difference in magnification associated with differences in the thickness of the cornea was not found. There was a significant negative correlation (Pearson) between age and cell density: correlation coefficient 0.395, significance P = 0.001. Regression analysis of this correlation gave the following equation: C_L = 3081 – 8.8 L, where C_L = cell density at age L. The error is 97 cells more or less than this figure.     

标准同轴晶状体乳化与微小切口白内障手术:一项角膜内皮的研究

目的:评估新的微小切口白内障手术(MICS)是否较标准同轴晶状体乳化引起较少的内皮损害方法:年龄相关性白内障患者 200 例随机分配接受标准同轴晶状体乳化(SCP)或 MICS 晶状体乳化。术前及术后1a 测量角膜中央及 12 点内皮细胞计数、细胞大小变异系数、六角形细胞百分比以及角膜中央厚度。结果:患者 173 例完成了试验。在 1a 的随访检查中,MICS 组内皮细胞损失为 6.5204%,而 SCP 组为 8.726%(P<0.00005)。两组在细胞大小变异系数、六角形细胞百分比、术后角膜厚度以及在切口部位和角膜中央测得的内皮细胞密度变异方面无显著差异。在硬性白内障患者中,与手术步骤无关,内皮细胞密度损失的增加量较高。结论:比较 SCP 与 MICS,本研究表明后者引起的内皮细胞密度损失明显地较低。