Subconjunctival injections. Preservative-related changes in the corneal endothelium

The morphologic effects on rabbit corneal endothelium of several common ophthalmic vehicle constituents were examined following subconjunctival administration. Profound dose-dependent changes consisting of intercellular vacuolization and thickening of the endothelial layer were noted within 1 day following administration of solutions that contained sodium bisulfite or methylparaben and propylparaben. These changes persisted for at least 5 days except in those eyes treated with the lowest concentration of sodium bisulfite. In contrast, administration of sodium citrate and creatinine or unpreserved normal saline resulted in only minimal effects. These changes are of concern because these agents are present in many preparations used to treat a wide variety of eye diseases.     

准分子激光角膜上皮下磨镶术对角膜内皮细胞的影响

目的探讨准分子激光角膜上皮下磨镶术(laser-assisted subepithelial keratomileusis,LASEK)对角膜内皮细胞的影响.方法收集2002年1月至7月在我所行LASEK治疗的近视眼患者90例病例资料(158只眼),按术前是否配戴角膜接触镜分为A、B两组A组未配戴CL,共65例(111只眼);B组配戴CL并于停戴2 w后接受手术,共25例(47只眼).术前等效球镜屈光度-6.00～-19.50 D,平均为(-10.23±1.29)D,术中激光切削深度72～203 μm,平均为(126.82±29.79)μm.分别于术前和术后3个月行角膜内皮显微镜检查,观察角膜内皮细胞密度和形态,并分析切削深度与内皮细胞密度的相关性.结果A组术前平均角膜内皮细胞密度为(2939.50±344.92)个/mm2,术后3个月为(2975.10±371.38)个/mm2,两者比较差异无显著性(t=0.74,P＞0.05).B组术后平均角膜内皮细胞密度较术前增加(251.6±107.5)个/mm2,差异有非常显著性(t=3.648,P<0.01).术后角膜内皮细胞形态结构无明显改变.A组角膜切削深度与术后平均角膜内皮细胞密度无显著相关性(r=0.0297,P＞0.05).结论LASEK术后早期不引起中央部角膜内皮细胞密度和形态的改变,是一种矫正高度近视眼安全的角膜屈光手术,但其对角膜内皮细胞的远期影响有待于进一步观察研究.     

LASIK对角膜内皮细胞的影响

目的：研究激光角膜原住磨镶术（LASIK）前后国人角膜内皮细胞密度和形态的改变,方法：选择无配戴接触镜史的-6.00~－26．00D（-11.89±4.58D）高度近视患眼利眼进行LASIK治疗,按照角膜切削面距离角膜内皮层厚度分为两组,组1：28眼为200~250μm,组2：13眼为251~300μ,各组患眼于术前和术后第3、10天、1、3个月观察和分析角膜内皮的细胞密度、变异系数和六角形细胞百分比,结果：①各级术前、术后的角膜内皮细胞密度、变异系数或六角形细胞百分比差异均无显著性意义（P＞0.05）;②角膜内皮细胞密度、变异系数或六角形细胞百分比的改变与切削面距离内皮层厚度不存在统计学的相关性,结论：激光角膜原位磨镶术不引起中央部角膜内皮细胞密度和形态的改变,是矫正高度近视一种安全的屈光手术,对于以切削后切削面距离角膜内皮层厚度200μum作为安全性的指标尚需作进一步的论证。     

准分子激光原位角膜磨镶术对角膜内皮细胞的影响

目的探讨准分子激光角膜原位磨镶术（LASIK）后角膜厚度及角膜内皮细胞的变化。方法近视眼行LASIK手术157例（306只眼）,按术前是否配戴角膜接触镜（CL）分为A、B两组：A组未配戴CL,共98例（190只眼）;B组配戴CL并于停戴2周后接受手术,共59例（116只眼）。术前等值球镜屈光度～5．00 D～1500D,平均为（～8．24±1．23）D,切削深度平均为（123±20．37）μm。分别于术前和术后3个月行角膜内皮显微镜检查,观察角膜内皮细胞密度和形态,并分析切削深度与内皮细胞的相关性。结果A组术前平均角膜内皮细胞密度为（3006．35±345．11）个／mm^2,术后3个月为（3056．75±357．36）个／mm^2,两者比较差异无显著性（P〉0．05）。B组术后平均角膜内皮细胞密度较术前增加（260．7±102．4）个／mm^2,有显著性差异（P〈0．01）。术后角膜内皮细胞形态结构无明显改变。A组角膜切削深度与术后平均角膜内皮细胞密度无显著相关性,（r=0．0267,P〉0．05）。结论LASIK术后早期不引起中央部角膜内皮细胞密度和形态的改变,是一种矫正近视眼安全的角膜屈光手术,但其对角膜内皮细胞的远期影响有待于进一步观察研究。     

角膜内皮炎的角膜内皮细胞形态改变

目的探讨角膜内皮炎对患者中央角膜内皮细胞形态的影响。方法用EM-1000型接触式角膜内皮镜对10例单眼角膜内皮炎愈后4-12周的患者的双眼分别摄取中央角膜内皮像并对其图像进行电脑分析。患眼作为实验组。健眼作为对照组。观察其角膜内皮细胞密度。六角形细胞的百分比及异形性的变化。用计量资料配对设计的2样本均数的t检验进行统计分析（双侧检验，P〈0．01为统计学有差异）。结果在10例临床诊断角膜内皮炎愈后的患者中，中央角膜内皮细胞密度实验组平均为（1981±181）／mm^2。对照组平均为（2284±315）／mm^2。六角形细胞比例实验组平均为34％，对照组平均为43％．变异系数实验组平均为53％，对照组平均为45％．以上各项观察指标实验组与对照组之间在统计学上都存在显著性差异（P〈0．01）。结论角膜内皮炎对角膜内皮细胞造成损伤，导致严重的形态改变，在临床工作中应给予充分重视。[眼科新进展2007；27（2）：138-139]     

Image analysis of morphologic features of the corneal endothelium including hexagonality

We developed an analysis system for the evaluation of corneal endothelial photographs. Morphological parameters including hexagonality were analyzed semiautomatically with this system. The image analyzer used consists of an image processor MC68000 and image memories 512 x 512 x 17bytes in size. The algorithm that measures the number of apices of each cell is as follows. First, all crossing points of cell borders are detected. Then, each cell is enlarged in order by three pixels in eight directions. The number of crossing points which are overlapped with an enlarged cell is detected as the number of apices of the cell. The analysis time was 7.44 +/- 1.48 min. (mean +/- standard deviation) for 40 endothelial photographs which needed no manual trace for contrast enhancement.     

眼科激光对角膜内皮的影响

目的观察Nd：YAG激光及532nm激光对角膜内皮细胞的影响。方法用角膜内皮细胞显微镜分别对Nd：YAG激光周边虹膜切除术以及后囊膜切开术的患眼和532nm激光治疗中心性浆液性脉络膜视网膜病变（CSC）及糖尿病性视网膜病变（DR）的患眼进行角膜内皮细胞的观察。结果所有行Nd：YAG激光治疗患者激光术后14d,中央角膜细胞密度（CD）减少,具有统计学意义（P〈0.05）;激光虹膜切除术后14d,中央部位CD减少,有统计学意义（P〈0.05）;术后7d,周边爆破处平均细胞面积（AVE）、最小细胞面积（MIN）、CD及六边形细胞百分率（6A）的变化均具有统计学意义（P〈0.05）;激光治疗后发性白内障后7d及14d中央部位及爆破处角膜内皮细胞的各项检测指标的改变均无统计学意义（P〉0.05）。532nm激光光凝治疗CSC、DR后角膜内皮细胞的各项检测指标的改变均无统计学意义（P〉0.5）。结论Nd：YAG激光周边虹膜切开术对角膜内皮有一定的损伤。532nm激光治疗CSC及DR对角膜内皮细胞造成的影响没有统计学意义。     

Metabolic analysis of the diseased human corneal endothelium]

Redox states of the corneal endothelium in 42 recipient corneas obtained at the penetrating keratoplasty were measured non-invasively using ocular redox fluorometry. Autofluorescence from reduced pyridine nucleotides (PN) and oxidized flavoproteins (Fp) were measured, and the PN/Fp ratio was used as an indicator of the redox state. Endothelial damage was graded as normal, mildly damaged, moderately damaged, and severely damaged, based on the histopathological findings. Mildly damaged endothelium showed a significantly higher PN/Fp ratio than the that in normal endothelium whereas the ratio was significantly lower in the severely damaged endothelium. These changes in the redox state may represent compensation and decompensation processes of the endothelial metabolism. Ocular redox fluorometry was shown to be useful for the evaluation of the metabolic state in the human corneal endothelium.     

The effects of 5-fluorouracil and mitomycin C on the corneal endothelium.

5-Fluorouracil (5-FU) and Mitomycin C (MMC) are used as adjunct chemotherapy during glaucoma filtering surgery to suppress conjunctival fibroblast proliferation. Since part of these agents may gain access to the anterior chamber and cause cytotoxicity to the corneal endothelium we set up an in vitro system to establish a dose-response effect. Cytotoxicity of MMC and 5-FU was quantified using Mosmann's colorimetric assay in a bovine endothelial cell culture system. In this assay the respiratory activity of the cells is used as a marker for cell viability. After incubation for 5 minutes the 3.0 mg/ml concentration of MMC showed endothelial cytotoxicity, whereas no endothelial toxicity of 5-FU was noted in concentrations up to 50 mg/ml. After incubation for 30 minutes endothelial cytotoxicity was demonstrated for 50 mg/ml of 5-FU and 1 mg/ml of MMC. After an exposure-time of 60 minutes the toxicity level remained 50 mg/ml for 5-FU but decreased to 0.5 mg/ml for MMC. We conclude that with respect to the clinically used concentrations and methods of application of 5-FU and MMC in vivo endothelial toxicity is not to be expected. However, in cases of accidental access of MMC to the anterior eye chamber and following a reduction of aqueous turnover rate the safety of MMC is unwarranted.     

The effects of UV-B irradiation on the corneal endothelium

Rabbit eyes, in vivo and in vitro, were exposed to UV-B irradiation at 300 nm, from a mercury arc lamp with an 11 nm bandpass filter. Radiant exposure ranged from 0.1 J/cm2 to 0.5 J/cm2. In vivo, swelling of the cornea resulted over a 12 to 40 hr period, the extent and duration being directly related to exposure. Recovery of normal thickness was complete within four days. Corneas removed at 18 hr after exposure recovered normal thickness during a five hour perfusion period, except for those most heavily exposed. When removed at 42 hr post exposure all corneas thinned to almost normal thickness. SEM showed the endothelial cells of exposed eyes to have either exaggerated villi on the surface and a disorganized mosaic or, after higher exposures, to be devoid of villi and have loose, flap like cell borders and large "blebs." After exposure of isolated corneas mounted for perfusion, swelling again ensued and similar changes were observed in the appearance of the cells, except that "blebs" were not found. No significant changes were observed in the metabolic components ATP, ascorbate and glutathione, nor was there any indication of lipid peroxidation. At higher in vivo exposures, the aqueous humor did show a decrease in ascorbate concentration and an increase in protein content, which probably result from a breakdown of the blood-aqueous barrier. UV-B irradiation may cause or promote changes in the endothelium associated with aging, but the one time radiant exposures of the magnitude used in this study, appear to have no severe or permanently toxic effects.     

Nd:YAG激光对角膜内皮的影响

目的 观察Nd：YAG激光对角膜内皮细胞的影响。方法 用角膜内皮细胞显微镜对Nd：YAG激光虹膜切除术以及后囊膜切开术的患眼进行角膜内皮细胞的观察。结果 所有患者激光术后14d，中央角膜内皮细胞密度（CD）减少具有统计学意义（P〈0．05）。激光虹膜切除术后14d，中央部位角膜内皮细胞密度减少，有统计学意义（P〈0．05）；术后7d，周边部5点处角膜内皮细胞平均细胞面积、最小细胞面积、细胞密度及六角形细胞百分率的变化均具有统计学意义（P〈0．05）。激光治疗后发性白内障后7d及14d中央部位及5点处角膜内皮细胞的各项检测指标的改变均无统计学意义（P〉0．05）；治疗前后患眼中央部位与周边5点处角膜内皮各项指标比较均无统计学差异，（P〉0．05）。结论 Nd：YAG激光周边虹膜切开术对角膜内皮有一定的损伤。2．6～3．2mj能量的Nd：YAG激光治疗后发障对角膜内皮细胞造成的损伤没有统计学意义。     

眼球挫伤对角膜内皮细胞的影响

目的探讨眼球挫伤对角膜内皮细胞形态的影响。方法应用非接触型角膜内皮显微镜对有眼球挫伤史者27例（54只眼）的伤眼（27只眼）及对侧健眼（27只眼）角膜内皮细胞进行观察,测量数据以SPSS16．0进行统计学分析。结果角膜内皮细胞密度眼球挫伤组为（1840．80±332．87）／mm2较健眼组的（2694．30±211．32）／mm2下降（t=9．729,P〈0．01）;平均细胞面积挫伤组为（568．16±147．61）μm。较健眼组的（359．33±69．07）μm2增大（t=6．463,P〈0．01）;平均细胞而积的标准差挫伤组为243．41±135．45较健眼组的161．12±19．00增大t=4．765,P〈0．01）;细胞面积的变异系数挫伤组为（41．10±10．17）％较健眼组的（31．01±3．53）％增大（f=4．915,P〈0．01）;六角形细胞所占比例挫伤组为（49．88±9．07）％较健眼组的（57．71±5．30）％降低（t=3．581,P〈0．01）。结论眼球挫伤可致角膜内皮细胞单位面积细胞密度F降、平均细胞面积增大、平均细胞面积的标准差增大、细胞面积的变异系数增加和六角形细胞所占比例下降。     

激光周边虹膜切除术对角膜内皮细胞的影响

目的 探讨Nd∶YAG激光周边虹膜切除术对角膜内皮细胞的影响.方法 采用非接触式角膜内皮显微镜对40例Nd∶YAG激光周边虹膜切除术的患眼进行角膜内皮细胞的定性及定量观察.检测指标包括:所选区域平均细胞面积(AVE)、最大细胞面积(MAX)、最小细胞面积(MIN)、细胞密度(CD)、变异系数(CV)、细胞面积标准差(SD).激光治疗后1周、1个月、3个月、6个月随访,重复作角膜内皮细胞检查及眼科常规检查.采用SAS Version 9.12 Mixed Model统计分析比较激光治疗前与激光治疗后不同时期的角膜内皮细胞密度及形态的改变.结果 激光治疗前与激光治疗后不同时期的角膜内皮细胞密度、平均细胞面积、最大细胞面积、变异系数,细胞面积标准差均有统计学意义.而角膜内皮细胞的最小细胞面积激光治疗前后比较无统计学意义.结论 Nd∶YAG激光周边虹膜切除术对角膜内皮细胞有一定的损伤.     

Kv3.3 potassium channels in lens epithelium and corneal endothelium

Human Kv3.3/KCNC3 is a Shaw-type potassium channel that has been mapped to chromosome 19q13.3-13.4. Complete mouse and rat Kv3.3 cDNA coding sequences have been published, yet the human Kv3.3 cDNA has remained incomplete for years. We report here for the first time the amino acid sequence for hKv3.3 and the electrophysiological behavior of the encoded channel in transiently transfected mammalian cells. In addition, we report the occurrence of Kv3.3 message in rabbit corneal endothelial cells and the properties of the currents when the corneal channel is expressed. The hKv3.3 gene is highly GC-rich (69%) and contains numerous GC runs which made DNA sequencing and PCR amplification especially problematic. The full-length sequence contains two possible start codons. The encoded 757 amino acid hKv3. 3 protein is about 93% identical to mouse and rat Kv3.3 in the first 659 amino acids before the C-terminal domains diverge greatly as a result of alternative splicing. The rabbit cornea Kv3.3 is a close sequence match for hKv3.3 even in the C-terminal domain. However, we have not yet found a cornea sequence which contains the first potential start codon from hKv3.3. Electrophysiologically, the hKv3. 3 channel produces an A-current although expression of constructs which lack the 5' region of the first start codon inactivate much more slowly than full-length constructs. This short hKv3.3 construct also shows changes in activation.     

Early morphological changes in organ cultured human corneal endothelium.

Nineteen human cadaver corneas with few damaged endothelial cells were incubated under tissue culture conditions for time periods ranging from five min to 48 h. Morphological alterations of the endothelial cells were studied in whole wet mounts stained by alizarine red-alkohol-trypane blue and by scanning electron microscopy. Joint meetings of three cells are characteristic for normal corneal endothelium. After 15--60 min of incubation, damaged cells were expelled from the coherent cell sheet by expanding neighbouring cells. Joint meetings of 5--8 expanding cells were formed. After 24 h of incubation, joint meetings of four cells were the dominating morphological abnormality. Morphological changes during reduction of the numbers of cells in joint meetings are described.     

Corneal endothelium variants in the area of corneal changes

Contact specular microscopy of the corneal endothelium and subsequent image analysis permit investigations of corneal endothelium reactions after circumscribed corneal damage. The extent and development of an endothelial process can thus be estimated.     

The effects of prolonged phacoemulsification time on the corneal endothelium

The question of whether or not phacoemulsification causes significant corneal endothelial damage has been studied in many ways. In this study, we used videotaped specular microscopy and nitroblue tetrazolium (NBT) staining to assess cell damage under conditions in which the two most commonly blamed sources of damage--probe tip trauma and lens fragments--cannot be implicated. After 15 minutes of irrigation, aspiration, and ultrasound in a modified corneal viewing and storage (CVS) chamber, the four test corneas showed less than 5% cell damage as assessed by NBT staining, which was no more than in the control. In one case, an unexpected air bubble on the endothelium caused a loss of endothelial cells. Because small air bubbles are common during phacoemulsification, and because such air bubbles may represent a cause of endothelial cell loss, the endothelial damage caused by air bubbles during phacoemulsification merits further study.