圆锥角膜基底下神经与角膜形态的相关性研究

目的 研究圆锥角膜（KC）基底下神经与角膜形态的相关性。设计 前瞻性比较性病例系列。研究对象 2018年3月至2019年3月北京同仁医院KC患者（KC组）74例74眼,KC顿挫期组25例25眼,正常对照组24例24眼。方法 通过眼部检查及Pentacam眼前节分析仪诊断KC、KC顿挫期及正常角膜。角膜形态参数采用Pentacam的角膜最大曲率值（Kmax）和角膜最薄厚度值（Minpachy）。应用ACCmetrics软件计算由活体激光共聚焦显微镜（IVCM）获得的基底下神经图片上六种基底下神经参数：角膜神经纤维密度（CNFD）、角膜神经分支密度（CNBD）、角膜神经纤维长度（CNFL）、角膜总分支密度（CTBD）、角膜神经纤维面积（CNFA）、角膜神经纤维宽度（CNFW）。分析KC组角膜基底下神经与角膜形态的相关性,并比较各两组间角膜基底下神经参数的差异。主要指标 Kmax、Minpachy、CNFD、CNBD、CNFL、CTBD、CNFA、CNFW。结果 IVCM定性分析观察到KC组角膜基底下神经迂曲度增加、基底下神经纤维密度明显低,偶可见神经呈束状排列。KC组和正常对照组比较,CNFD、CNBD、CNFL和CNFW差异均有统计学意义（P均<0.05）。KC组和顿挫组比较,CNFL和CNFA差异均有统计学意义（P均<0.05）。顿挫组和正常对照组比较,CNFD和CNFL差异均有统计学意义（P均<0.05）。KC组CNFD、CNFL和CNFW分别与Kmax具有相关性（P=0.001、0.001和0.006）, KC组的CNFD、CNBD、CNFL和CNFW分别与Minpachy具有相关性（P=0.01、0.01、0.004和0.02）。结论 KC患者角膜基底下神经的改变可能早于角膜形态的改变,基底下神经随着疾病的进展而变化。CNFD和CNFL可能是诊断早期圆锥角膜的指标。（眼科, 2020, 29： 118-122）     

Protective effects of piperine on the retina of mice with streptozotocin-induced diabetes by suppressing HIF-1/VEGFA pathway and promoting PEDF expression

AIM: To evaluate the protective mechanisms of piperine in the retina of mice with streptozotocin-induced diabetes. METHODS: In experiments in vitro, stimulation by chemical hypoxia was established in ARPE-19 cells. Then, the expression of hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor A (VEGFA), and pigment epithelium-derived factor (PEDF) was assessed at the mRNA and protein levels. In experiments in vivo, diabetes mellitus was established by intraperitoneally injecting 150 mg/kg streptozotocin once. After 3wk of the onset of diabetes, 15 mg/kg piperine was intraperitoneally injected once daily for 1 or 3wk. Then, the retinal morphology and mRNA and protein expression were assessed. RESULTS: In hypoxia, 1-100 μmol/L piperine significantly decreased the expression of VEGFA mRNA and increased the expression of PEDF mRNA without affecting HIF-1α mRNA. Meanwhile, 100 μmol/L piperine substantially decreased the protein level of VEGFA and increased the protein level of PEDF. The HIF-1α protein level was also hampered by piperine. In the diabetic retina of mice, the morphological damage was alleviated by piperine. Likewise, the retinal vascular leakage was substantially decreased by piperine. Further, the protein levels of HIF-1α and VEGFA were significantly reduced by piperine. Moreover, the level of the antiangiogenic factor of PEDF dramatically increased by piperine. CONCLUSION: Piperine may exert protective effects on the retina of mice with diabetes via regulating the pro-antiangiogenic homeostasis composed of HIF-1/VEGFA and PEDF.     

Efficacy and outcome of simple limbal epithelial transplantation for limbal stem cell deficiency verified by epithelial phenotypes integrated with clinical evaluation

PurposeTo evaluate the efficacy and outcome of simple limbal epithelial transplantation (SLET) for limbal stem cell deficiency (LSCD) using epithelial phenotype detection integrated with clinical manifestation.MethodsThis prospective multicenter study included patients with LSCD who underwent autologous SLET (autoSLET) and living-related allogenic SLET (Lr-alloSLET). All patients were assessed by slit-lamp biomicroscopy, in vivo confocal microscopy (IVCM), and impression cytology with immunofluorescence staining (ICIF) before and after surgery. The criteria for success were the presence of a clinically non-conjunctivalized cornea and corneal epithelium detected by IVCM or ICIF. Otherwise, the case would be considered a failure. Visual improvement and risk factors for SLET failure were analyzed.ResultsA total of 28 eyes of 26 patients (11 autoSLET and 17 Lr-alloSLET) were included. The median age was 53 years (range, 35–63), and the follow-up time was 29.5 months (range, 17.5–39.8). The overall survival rate was 89.3% at 2 years and 75.6% at 3 years with no difference between autoSLET and Lr-alloSLET (p = 0.24). Seven eyes subsequently underwent penetrating keratoplasty. Immunohistochemistry analysis showed that all corneal buttons had corneal epithelium and limbal stem cell markers. Visual improvement was achieved in both SLET groups (p < 0.001). Failed SLET developed between 5 and 32 months postoperatively. However, absolute risk factors for SLET failure were unidentified.ConclusionThe efficacy of autoSLET and Lr-alloSLET for LSCD was excellent. Limbal explants can regenerate and restore the corneal surface while maintaining the characteristics of limbal stem cells as shown by epithelial phenotype detection and immunohistochemistry integrated with clinical evaluation.     

The utility of anterior segment optical coherence tomography angiography for the assessment of limbal stem cell deficiency

PurposeTo determine the utility of anterior segment optical coherence tomography angiography (AS-OCTA) in assessing limbal stem cell deficiency (LSCD).MethodsTwenty-six eyes of 24 LSCD patients, classified clinically into stage I, II and III, and 12 eyes of 12 healthy subjects were included. AS-OCTA images were analyzed by two masked observers, measuring the maximum corneal vascular extension (CoVE) from the limbus to the furthest vessel over the cornea, and corneal vascular thickness (CoVT) from the most superficial to the deepest corneal vessel.ResultsCoVE was 0.27 ± 0.10, 0.79 ± 0.21, 1.68 ± 0.89 and 2.53 ± 0.82 mm in controls, stage I, II and III LSCD, respectively (p < 0.001). The CoVT was 51.0 ± 19.4, 113.7 ± 36.6, 129.7 ± 39.3 and 336.0 ± 85.0 μm, respectively (p < 0.001). There was a significant difference in CoVE and CoVT between all stages compared to controls, and between stage I and III LSCD (p < 0.001). Further, CoVE showed a significant difference between stage I and II, whereas CoVT showed a significant difference between stage II and III LSCD (p < 0.001). BCVA showed strong correlation with CoVT (r = 0.765, p < 0.001) and moderate correlation with CoVE (r = 0.547, p = 0.001). AS-OCTA parameters showed excellent intra- and inter-class correlation coefficients (>0.900).ConclusionLSCD demonstrates significant changes in CoVE and CoVT as early as stage I LSCD in comparison to controls. CoVE and CoVT strongly correlate to both disease severity and BCVA. AS-OCTA may provide novel quantitative and non-invasive parameters to assess LSCD.     

白内障手术不同方向角膜切口对术后泪膜稳定性及角膜神经损伤修复的影响

目的：分析白内障超声乳化术不同方向的透明角膜切口对年龄相关性白内障（ARC）及糖尿病性白内障（DC）患者泪膜稳定性及角膜神经损伤修复的影响。方法：前瞻性研究。收集2021年9—12月常州市第三人民医院眼科行超声乳化吸除联合人工晶状体（IOL）植入术的白内障患者67例（80眼）,其中ARC患者35例（40眼）,DC患者32例（40眼）。ARC患者按随机数字表法分为2组：Ⅰ组18例（20 眼）行上方透明角膜切口;Ⅱ组17例（20眼）行颞侧透明角膜切口。DC患者按随机数字表法分为2 组：Ⅲ组16例（20眼）行上方透明角膜切口;Ⅳ组16例（20眼）行颞侧透明角膜切口。术前,术后1 周、1个月及3个月时行泪膜破裂时间（BUT）、泪河高度（TMH）、泪液分泌试验Ⅰ（SⅠT）检查;术后1周、1个月及3个月时行眼前节光学相干断层成像扫描（AS-OCT）检查;术后1个月及3个月时行角膜共焦显微镜（CCM）检查。各组术后BUT、TMH、SⅠT与术前比较采用t检验;角膜神经纤维主干密度（CNFD）、角膜神经纤维分支密度（CNBD）组间比较采用单因素方差分析。角膜神经纤维长度（CNFL）、角膜神经纤维宽度（CNFW）组间比较采用非参数Mann-Whitney检验。结果：术后l周、1个月,4组患者BUT、TMH、SⅠT与术前相比差异均有统计学意义（均P<0.05）。术后1周,Ⅰ组与Ⅲ组相比、Ⅱ组与Ⅳ组相比,BUT、TMH、SⅠT值均较大,差异均有统计学意义（均P<0.05）;术后1 个月时,差异无统计学意义（P>0.05）。术后1个月,所有患者完整的长神经纤维均很少;术后3个月,4组均可见完整长神经纤维且可见神经纤维束连接。与术后1个月相比,术后3个月4组患者CNFL、CNFD、CNBD均升高（均P<0.05）。术后1个月Ⅳ组与Ⅲ组相比,CNFL、CNFD、CNBD均较低（均P<0.05）;术后1、3个月,Ⅰ组与Ⅲ组相比、Ⅱ组与Ⅳ组相比,CNFL、CNFD、CNBD均较高,差异均有统计学意义（均P<0.05）。结论：行白内障手术时,DC患者上方角膜切口对神经的损伤较颞侧切口轻。DC患者眼表泪膜损伤及角膜神经损伤比ARC患者修复慢。     

高度近视行不同激光角膜屈光术后角膜神经纤维的修复情况比较

目的： 探讨高度近视患者行飞秒激光小切口角膜基质透镜取出术（ SMILE）、飞秒激光制瓣的准分子 激光原位角膜磨镶术（ FS-LASIK）以及准分子激光角膜上皮瓣下磨镶术（ LASEK）后早中期角膜各区 域上皮下神经纤维的修复情况。 方法： 前瞻性临床研究。选择2018年6月至2020年12月在青岛大学 附属医院眼科就诊并进行屈光手术矫正的高度近视患者55 例（ 110 眼），按手术方式不同分为SMILE 组22 例（ 44 眼）、 FS-LASIK组18 例（ 36 眼）、 LASEK组15 例（ 30 眼）。各组于术后1、 3、 6 个月行激光 共聚焦显微镜检查，观察角膜各区域神经纤维的修复情况。对术后不同时间各组间的神经纤维各 参数的比较采用随机区组设计的单因素方差分析。 结果： 高度近视患者行SMILE术后早期不同区 域的角膜神经密度、分支密度、长度及宽度较FS-LASIK和LASEK术后更佳，修复速度也更快，较 早达到术前水平。而FS-LASIK术后包括角膜瓣在内的不同区域的角膜神经修复情况居于SMILE和 LASEK之间， LASEK术后早期特别是中央区白色瘢痕样混浊明显，且不同区域的角膜修复速度最慢、 质量最差。术后1 个月， SMILE组和FS-LASIK组术后中央的角膜神经密度（ CNFD）、神经纤维长度 （ CNFL）、神经分叉节点密度（ CTBD）明显优于LASEK组，差异均有统计学意义（均P<0.05）； SMILE 组的主要神经分叉节点密度（ CNBD）明显优于FS-LASIK组和LASEK组（ HSD=4.367， P=0.005； HSD=4.237， P=0.008）。术后3 个月， SMILE组中央CNFD、 CNBD、 CNFL明显优于FS-LASIK和 LASEK组（均P<0.05）； LASEK组神经纤维宽度（CNFW）明显优于SMILE和FS-LASIK组（HSD=3.457， P=0.003； HSD=3.668， P=0.004）。术后6 个月， SMILE组中央CNFD、 CNBD以及CNFL均优于FSLASIK和LASEK组（均P<0.05）。 结论： 高度近视患者行激光角膜屈光术后早中期， SMILE各区域的 神经修复情况较FS-LASIK和LASEK均有显著的领先优势。
     

Clinical and cytological findings in limbal stem cell deficiency

Purpose To evaluate and relate the clinical (including corneal sensitivity and tear function) and cytological (presence of goblet cells and cytokeratin 3- and 19-positive cells) features of limbal stem cell deficiency (LSCD).Methods Twenty-nine patients (44 eyes) with a clinical diagnosis of LSCD participated in this study. Corneal signs (epithelial alterations, superficial neovascularisation and stromal scarring) and cytological findings (presence of goblet cells and cytokeratins 3 and 19) were evaluated and scored (from 0 to 3) from each of the five corneal sectors. Corneal sensitivity (Cochet-Bonnet aesthesiometer) and tear function (Schirmer test and BUT) were also assessed. Cytological scores were correlated statistically with both corneal signs and sensitivity values.Results Cytokeratin 19-positive cells were found in 82% of corneal impression cytology samples, while goblet cells were identified in only 59% of these same samples. Cytokeratin 3-positive cells were present in 61% of LSCD eyes and in all unaffected eyes. Corneal sensitivity was significantly decreased in affected eyes compared with contralateral, healthy eyes (1.6±1.7 cm versus 5.7±0.3 cm). Tear function tests did not show significant changes. In LSCD eyes, goblet cells and cytokeratin 19-positive cells on the corneal surface were significantly correlated to corneal epithelial alterations and to corneal superficial neovascularisation (p<0.001). Corneal cytokeratin 3-positive cells were inversely related to epithelial alterations (p=0.003). Corneal sensitivity was decreased in corneal sectors with epithelial alterations (p<0.001), neovascularisation (p<0.001) and stromal abnormalities (p=0.049), and was indirectly related to the presence of goblet cells (p=0.005) and cytokeratin 19-positive cells (p<0.001).Conclusion This study confirmed the importance of cytological tests in the diagnosis of LSCD. Furthermore, the absence of goblet cells may not exclude corneal conjunctivalisation as demonstrated by cytokeratin 19 immunostaining. Lastly, corneal conjunctivalisation was associated with zone-specific impairment in corneal sensitivity.This study was presented at the Annual Meeting of the Association for Research in Vision and Ophthalmology, 4–11 May 2002, Fort Lauderdale, Florida.     

Tissue engineered corneal epithelium derived from clinical-grade human embryonic stem cells

PurposeTo construct tissue engineered corneal epithelium from a clinical-grade human embryonic stem cells (hESCs) and investigate the dynamic gene profile and phenotypic transition in the process of differentiation.MethodsA stepwise protocol was applied to induce differentiation of clinical-grade hESCs Q-CTS-hESC-1 and construct tissue engineered corneal epithelium. Single cell RNA sequencing (scRNA-seq) analysis was performed to monitor gene expression and phenotypic changes at different differentiation stages. Immunostaining, real-time quantitative PCR and Western blot analysis were conducted to detect gene and protein expressions. After subcutaneous transplantation into nude mice to test the biosafety, the epithelial construct was transplanted in a rabbit corneal limbal stem cell deficiency (LSCD) model and followed up for eight weeks.ResultsThe hESCs were successfully induced into epithelial cells. scRNA-seq analysis revealed upregulation of ocular surface epithelial cell lineage related genes such as TP63, Pax6, KRT14, and activation of Wnt, Notch, Hippo, and Hedgehog signaling pathways during the differentiation process. Tissue engineered epithelial cell sheet derived from hESCs showed stratified structure and normal corneal epithelial phenotype with presence of clonogenic progenitor cells. Eight weeks after grafting the cell sheet onto the ocular surface of LSCD rabbit model, a full-thickness continuous corneal epithelium developed to fully cover the damaged areas with normal limbal and corneal epithelial phenotype.ConclusionThe tissue engineered corneal epithelium generated from a clinical-grade hESCs may be feasible in the treatment of limbal stem cell deficiency.     

Neuronal-epithelial cell alignment: A determinant of health and disease status of the cornea

PurposeHow sensory neurons and epithelial cells interact with one another, and whether this association can be considered an indicator of health or disease is yet to be elucidated.MethodsHerein, we used the cornea, Confetti mice, a novel image segmentation algorithm for intraepithelial corneal nerves which was compared to and validated against several other analytical platforms, and three mouse models to delineate this paradigm. For aging, eyes were collected from 2 to 52 week-old normal C57BL/6 mice (n ≥ 4/time-point). For wound-healing and limbal stem cell deficiency, 7 week-old mice received a limbal-sparing or limbal-to-limbal epithelial debridement to their right cornea, respectively. Eyes were collected 2–16 weeks post-injury (n=4/group/time-point), corneas procured, immunolabelled with βIII-tubulin, flat-mounted, imaged by scanning confocal microscopy and analyzed for nerve and epithelial-specific parameters.ResultsOur data indicate that nerve features are dynamic during aging and their curvilinear arrangement align with corneal epithelial migratory tracks. Moderate corneal injury prompted axonal regeneration and recovery of nerve fiber features. Limbal stem cell deficient corneas displayed abnormal nerve morphology, and fibers no longer aligned with corneal epithelial migratory tracks. Mechanistically, we discovered that nerve pattern restoration relies on the number and distribution of stromal-epithelial nerve penetration sites.ConclusionsMicrostructural changes to innervation may explain corneal complications related to aging and/or disease and facilitate development of new assays for diagnosis and/or classification of ocular and systemic diseases.     

Corneal Keratocyte Density and Corneal Nerves Are Reduced in Patients With Severe Obesity and Improve After Bariatric Surgery

PurposeObesity is associated with peripheral neuropathy, which bariatric surgery may ameliorate. The aim of this study was to assess whether corneal confocal microscopy can show a change in corneal nerve morphology and keratocyte density in subjects with severe obesity after bariatric surgery.MethodsTwenty obese patients with diabetes (n = 13) and without diabetes (n = 7) underwent assessment of hemoglobin A1c (HbA1c), lipids, IL-6, highly sensitive C-reactive protein (hsCRP), and corneal confocal microscopy before and 12 months after bariatric surgery. Corneal nerve fiber density (CNFD), corneal nerve branch density (CNBD), corneal nerve fiber length (CNFL), and keratocyte density (KD) from the anterior, middle, and posterior stroma were quantified. Twenty-two controls underwent assessment at baseline only.ResultsCNFL (P < 0.001), CNBD (P < 0.05), and anterior (P < 0.001), middle (P < 0.001), and posterior (P < 0.001) keratocyte densities were significantly lower in obese patients compared to controls, and anterior keratocyte density (AKD) correlated with CNFL. Twelve months after bariatric surgery, there were significant improvements in body mass index (BMI; P < 0.001), HDL cholesterol (P < 0.05), hsCRP (P < 0.001), and IL-6 (P < 0.01). There were significant increases in CNFD (P < 0.05), CNBD (P < 0.05), CNFL (P < 0.05), and anterior (P < 0.05) and middle (P < 0.001) keratocyte densities. The increase in AKD correlated with a decrease in BMI (r = –0.55, P < 0.05) and triglycerides (r = –0.85, P < 0.001). There were no significant correlations between the change in keratocyte densities and corneal nerve fiber or other neuropathy measures.ConclusionsCorneal confocal microscopy demonstrates early small fiber damage and reduced keratocyte density in obese patients. Bariatric surgery leads to weight reduction and improvement in lipids and inflammation and an improvement in keratocyte density and corneal nerve regeneration.     

Stem cell-based therapy for treating limbal stem cells deficiency: A review of different strategies

The self renewal capability of limbal epithelial stem (LEST) cells is fundamental to the maintenance and healing of corneal epithelium. Limbal stem cell deficiency (LSCD), due to dysfunction or loss of LEST cells, therefore presents as persistent epithelial defects, corneal vascularization, conjunctivalization etc. Stem cell-based therapy, in its simplest form – limbal autograft, has been used successfully for more than a decade. For bilateral LSCD, similar approaches with limbal allografts have been unsuccessful largely due to strong immune rejection. Therefore, as an alternate strategy for treating bilateral LSCD, ex vivo expansion of the remaining LEST cells or autologous stem cells sourced from other potential sites is being explored. Different culture systems (with and without xenobiotic supplements) using substrates like amniotic membrane or fibrin gels have been used successfully for ex vivo LEST cell maintenance and reproduction by imitating the stem cell niche. This paper is organized into sections reviewing the LEST cells, LSCD and various stem cell-based approaches for treating LSCD and discussing future direction and challenges.     

Small Nerve Fiber Damage and Langerhans Cells in Type 1 and Type 2 Diabetes and LADA Measured by Corneal Confocal Microscopy

PurposeIncreased corneal and epidermal Langerhans cells (LCs) have been reported in patients with diabetic neuropathy. The aim of this study was to quantify the density of LCs in relation to corneal nerve morphology and the presence of diabetic neuropathy and to determine if this differed in patients with type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM), and latent autoimmune diabetes of adults (LADA).MethodsPatients with T1DM (n = 25), T2DM (n = 36), or LADA (n = 23) and control subjects (n = 23) underwent detailed assessment of peripheral neuropathy and corneal confocal microscopy. Corneal nerve fiber density (CNFD), branch density (CNBD), length (CNFL) and total, immature and mature LC densities were quantified.ResultsLower CNFD (P < 0.001), CNBD (P < 0.0001), and CNFL (P < 0.0001) and higher LC density (P = 0.03) were detected in patients with T1DM, T2DM, and LADA compared to controls. CNBD was inversely correlated with mature (r = –0.5; P = 0.008), immature (r = –0.4; P = 0.02) and total (r = –0.5; P = 0.01) LC density, and CNFL was inversely correlated with immature LC density (r = –0.4; P = 0.03) in patients with T1DM but not in patients with T2DM and LADA.ConclusionsThis study shows significant corneal nerve loss and an increase in LC density in patients with T1DM, T2DM, and LADA. Furthermore, increased LC density correlated with corneal nerve loss in patients with T1DM.     

碱烧伤诱导兔部分性角膜缘干细胞失代偿模型

目的：探讨诱导兔部分性角膜缘干细胞失代偿(limbal stem cell deficiency,LSCD)动物模型的一种新方法。

方法：分别采用C57小鼠和新西兰白兔制作完全性和部分性角膜缘干细胞失代偿动物模型。小鼠(n=30)采用1mol/L氢氧化钾溶液浸泡的滤纸片(直径3mm)置于左眼中央角膜表面30s,随后用生理盐水冲洗。白兔(n=19)切除瞬膜(第三眼睑)后,采用1mol/L氢氧化钾溶液浸泡的滤纸片(直径5mm)置于左眼颞上方角膜表面30s,随后用生理盐水冲洗。烧伤眼术后采用0.5%盐酸左氧氟沙星滴眼液4次/d。烧伤前、烧伤后第1、2、4wk,2mo采用裂隙灯显微镜观察、摄像,记录角膜溃疡、穿孔等并发症。术后2mo采用印迹细胞学检测角膜杯状细胞分布,根据裂隙灯显微镜检查所见和角膜印迹细胞学检查判断LSCD严重程度。术后2mo处死动物,角结膜切片观察角膜新生血管、杯状细胞分布。意外死亡动物不计入总数,计算并比较完全性LSCD和部分性LSCD的模型诱导成功率。

结果：30只小鼠中6只意外死亡,2只于烧伤后出现角膜穿孔,其余22只发生完全性LSCD,诱导成功率92%,烧伤后2mo小鼠角膜可见新生血管广泛分布于角膜浅层及深基质层,病理切片可见角膜新生血管。19只白兔,7只意外死亡,其余12只发生不同程度LSCD(部分性LSCD,平均累及1.17±0.39个象限),未发生角膜穿孔情况,诱导成功率100%(P=0.543)。正常角膜区域无杯状细胞,LSCD区域角膜上皮印迹细胞学PAS染色可见杯状细胞,平均密度58.60±12.58个细胞/HP。

结论：中央角膜碱烧伤可以诱导产生完全性LSCD,部分动物会因为角膜溃疡穿孔而导致模型诱导失败,LSCD往往比较严重,且合并深层角膜新生血管。颞上方角膜碱烧伤可以诱导产生部分性LSCD,合并较少的角膜病变,角膜新生血管位于浅层。     

Stage-related central corneal epithelial transformation in congenital aniridia-associated keratopathy

Purpose

To relate central corneal epithelial phenotype to degree of keratopathy in a limbal stem cell deficient population.

A systematic review of cellular therapies for the treatment of limbal stem cell deficiency affecting one or both eyes

PurposeThis systematic review (SR) assessed the efficacy, safety and cost-effectiveness of cell-based therapy to manage limbal stem cell deficiency (LSCD), a sight-threatening orphan condition most frequently associated with severe chemical or thermal burns. LSCD has historically been treated by transplanting limbal tissue. In 1997, a new treatment, cultured limbal epithelial autografts, was described for unilateral LSCD. In cases of bilateral disease cultured autologous oral mucosa stem cells have been used. The relative efficacy of different cultured tissue procedures is unknown.MethodsA protocol was registered with PROSPERO (CRD42017081117). Searches were conducted in 14 databases and 6 conference websites. Two reviewers independently selected studies, conducted data extraction and assessed risk of bias. One reviewer extracted individual patient data (IPD); a second checked extracted data. Data were assessed to determine the feasibility of statistical analysis, with Bayesian synthesis used to estimate improvement achieved by different treatments.ResultsFifty-two studies were eligible for inclusion (1113 eyes); 41 studies (716 eyes) reported IPD. No evidence was identified on cost-effectiveness. This SR was unable to confirm that any of the types of ex vivo cultured stem cell transplants identified for LSCD treatment were statistically superior when assessed against the outcomes of interest.ConclusionsWe believe this SR is the first to include IPD analysis of LSCD data. There is no evidence for the superiority of any method of limbal stem cell transplant. Confirmation of the safety and efficacy of this treatment modality is challenging due to heterogeneity within and between the studies identified. Therefore, recommendations for future research are proposed.     

Bilateral Limbal Stem Cell Alterations in Patients With Unilateral Herpes Simplex Keratitis and Herpes Zoster Ophthalmicus as Shown by In Vivo Confocal Microscopy

PurposeThe purpose of this study was to investigate the limbal changes in the palisades of Vogt (POV) in patients with herpes simplex keratitis (HSK) and herpes zoster ophthalmicus (HZO) with the application of in vivo confocal microscopy (IVCM).MethodsWe enrolled 35 eyes of 35 consecutive patients with HSK and 4 patients with HZO in this observational study. Thirty-five participants were also recruited from a healthy population as the control group. All subjects were examined by IVCM in addition to routine slit-lamp biomicroscopy. The IVCM images of the corneal basal epithelial cells, corneal nerve, and the corneoscleral limbus were acquired and then were analyzed semiquantitatively.ResultsThe rate of absent and atypical POV was significantly higher in the affected eyes of patients with HSK than in the contralateral eyes and eyes of controls (88.57% vs. 65.71% vs. 17.14%, P < 0.01). In the HZO group, the rate of absent and atypical POV was 100% in the affected eyes and 50% in the contralateral eyes. When compared to the contralateral unaffected eyes and control eyes, the average density of the central basal epithelial cells and the sub-basal nerve plexus density and the total number of nerves in the central area of the affected eyes were significantly lower in the HSK group (1541 ± 704.4 vs. 2510 ± 746.8 vs. 3650 ± 746.1 cells/mm², P < 0.0001). Spearman''s rank correlation showed that the presence of absent and atypical POV had a significant negative correlation with central corneal basal epithelial cells (r_s = −0.44979, P < 0.0001), the density of total nerves (r_s = −0.49742, P < 0.0001), and the total nerve numbers (r_s = −0.48437, P < 0.0001). A significant positive correlation was established between the presence of absent and atypical POV and HSK severity in affected eyes in the superior, inferior, nasal, and temporal quadrants (r_s = 0.68940, r_s = 0.78715, r_s = 0.65591, and r_s = 0.75481, respectively, P < 0.0001) and the contralateral eyes (r_s = 0.51636, r_s = 0.36207, r_s = 0.36990, r_s = 0.51241, correspondingly, P < 0.0001).ConclusionsBoth eyes of patients with unilateral HSK and HZO demonstrated a profound and significant loss of limbal stem cells, which may explain the fact that HSK and HZO are risk factors for limbal stem cell deficiency (LSCD) in both eyes. The loss of LSCs was strongly correlated with the sub-basal nerve plexus and central basal epithelial cell alterations as shown by IVCM.     

Modified Allogenic Simple Limbal Epithelial Transplantation Followed by Keratoplasty as Treatment for Total Limbal Stem Cell Deficiency

Purpose: To describe a modified allogenic simple limbal epithelial transplant (SLET) technique with large donor tissue explants followed by keratoplasty.

Methods: A 69-year-old with conjunctival melanoma on her left eye developed total limbal stem cell deficiency (LSCD) after multiple cycles of topical mitomycin. She also had herpes stromal keratitis while on treatment with mitomycin. She underwent modified allogenic SLET with large donor limbal tissue explants glued on the cornea directly and the amniotic membrane placed over the limbal explants.

Results: Unfortunately she had recurrence of herpes simplex keratitis that caused worsening of stromal scarring and neovascularization. She underwent penetrating keratoplasty to improve vision. There were no postoperative complications and the corneal graft remains transparent 11 months after penetrating keratoplasty with 6/12 best-corrected visual acuity.

Conclusions: Modified SLET with large donor limbal explants followed by keratoplasty is an effective approach to restore corneal transparency in cases of total LSCD.     

Limbal Stem Cell Transplantation and Complications

ABSTRACT

Corneal epithelial stem cells are adult somatic stem cells located at the limbus and represent the ultimate source of transparent corneal epithelium. When these limbal stem cells become dysfunctional or deficient, limbal stem cell deficiency (LSCD) develops. LSCD is a major cause of corneal scarring and is particularly prevalent in chemical and thermal burns of the ocular surface. LSCD leads to conjunctivalization of the corneal surface, neovascularization, recurrent or persistent epithelial defects, ocular surface inflammation, and scarring that, in turn, lead to decreased vision, pain, and impaired quality of life. Several techniques have been reported for limbal stem cell transplantation (LSCT). We introduce the surgical techniques, examine the success rate, and discuss the postoperative complications of conjunctival limbal autograft (CLAU), cultivated limbal stem cell transplantation (CLET), simple limbal epithelial transplantation (SLET), and limbal allograft, including keratolimbal allografts (KLAL) and living-related conjunctival allograft (LR-CLAL).     

Innovative technique of mini-simple limbal epithelial transplantation in pediatric patients

In this article, we introduce a modified technique of minor ipsilateral simple limbal epithelial transplantation (mini-SLET) in pediatric patients of limbal stem cell deficiency (LSCD). Two children with unilateral partial LSCD underwent the innovative technique of mini-SLET, where harvested limbal tissues were placed over the raw cornea and were covered with amniotic membrane. Both patients were followed till 9 months. Both cases showed favorable outcome and uneventful recovery. Results were comparable with the classical technique. This innovative modification of mini-SLET is safe, feasible, and an effective alternative with favorable visual outcome especially in pediatric population. It can be a breakthrough for LSCD management in developing countries with limited resources.     

DR早期视网膜神经纤维层和角膜神经的变化及其相关性

目的:观察无视网膜微血管病变的糖尿病患者的视网膜神经纤维层(RNFL)和角膜神经纤维(CNF)变化,以及两者变化的相关性.方法:收集40例40眼2型糖尿病患者,经散瞳眼底检查未发现糖尿病视网膜病变,均接受光学相干断层扫描(OCT)检查和活体角膜共聚焦显微镜(IVCM)检查.另收集年龄匹配的80例80眼健康正常眼为对照,分为40例40眼只行OCT检查的RNFL对照组和40例40眼只行IVCM检查的CNF对照组.利用OCT观察视乳头上方、下方、颞侧、鼻侧和平均RNFL厚度,用IVCM观察角膜上皮下角膜神经纤维长度和角膜神经密度.结果:糖尿病组的视乳头上方、颞侧、鼻侧及平均RNFL与对照组比较,差异无统计学意义(P>0.05),但视乳头下方RNFL糖尿病组比RNFL对照组减少,差异有统计学意义(P=0.003).糖尿病组的角膜神经纤维长度、角膜神经密度均比CNF对照组减少(P<0.01).糖尿病组中,平均RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.518,P<0.01;r=0.484,P=0.002),下方RNFL与角膜神经纤维长度和角膜神经密度呈正相关(r=0.607,P<0.01;r=0.573,P<0.01).结论:糖尿病患者在未发现糖尿病视网膜病变前同时存在视网膜神经纤维层和角膜神经的丢失,视网膜神经纤维层变薄主要表现在下方象限,视网膜神经纤维层的变薄与角膜神经的减少呈正相关.