基质层角膜营养不良行角膜穿透性移植术后远期观察

目的：观察基质层角膜营养不良患者行角膜穿透移植术后的远期疗效。方法：对22例22眼基质层角膜营养不良患者行角膜穿透移植术进行治疗,并对其远期疗效进行分析。结果：随访时间2a-8a,22只术眼中有21眼角膜植片透明（95．04％）;视力＞0．3者14眼（63．3％,脱残率）。结论：通过2a-8a（平均为5．8a)的随访,并未见移植片的周边部发生基质层角膜营养不良的混浊现象,而且术后免疫排斥反应发生率低,可以证实角膜穿透性移植术是治疗基质层角膜营养不良的有效手术方法。     

A simple corneal perfusion chamber for drug penetration and toxicity studies

AIMS: Corneal perfusion chambers are important tools in the development and assessment of ophthalmic drugs. The aim of this study was to design and test a modified perfusion chamber suitable for topical application of drugs to isolated corneoscleral preparations, and which allowed continuous monitoring of endothelial cell function. METHODS: A polycarbonate and stainless steel perfusion chamber was designed to clamp corneas in a horizontal plane suitable for topical drug delivery. Endothelial cell function was assessed by ultrasonic pachymetry and specular microscopy during perfusion. Epithelial barrier function was assessed by penetration of fluorescein. Leakage was examined by measuring penetration of a large protein, IgG. Tissue architecture after perfusion was examined by conventional histology. RESULTS: Corneas maintained a functionally and morphologically intact endothelial monolayer during perfusion periods of up to 14 hours. The epithelial barrier function was well preserved. The tissue clamp sealed the preparation effectively against leakage of macromolecules. CONCLUSION: The new chamber device forms a reliable tool for in vitro drug penetration and toxicity studies in isolated perfused corneoscleral tissue.     

基质层角膜营养不良行角膜穿透性移植术后远期观察

目的观察基质层角膜营养不良患者行角膜穿透移植术后的远期疗效.方法对22例22眼基质层角膜营养不良患者行角膜穿透移植术进行治疗,并对其远期疗效进行分析.结果随访时间2～8年,22只术眼中有21眼角膜植片均为透明(95.4%);视力＞0.3者14眼(63.3%,脱残率).结论通过2～8年(平均为5.8年)的随访,并未见移植片的周边部发生基质层角膜营养不良的混浊现象,而且术后免疫排斥反应发生率低,可以证实角膜穿透性移植术是治疗基质层角膜营养不良的有效手术方法.     

基质层角膜营养不良行角膜穿透移植术后远期观察

目的　观察基质层角膜营养不良患者行角膜穿透移植术后的远期疗效。方法　对22例22眼基质层角膜营养不良患者行角膜穿透移植术进行治疗,并对其远期疗效进行分析。结果　随访时间2～8年,22只术眼中有21眼角膜植片均为透明(95.4%);视力>0.3者14眼(63.3%,脱残率)。结论　通过2～8年(平均为5.8年)的随访,并未见移植片的周边部发生基质层角膜营养不良的混浊现象,而且术后免疫排斥反应发生率低,可以证实角膜穿透移植术是治疗基质层角膜营养不良的有效手术。方法     

'Hot' corneal grafts--a long-term study

A six-year follow-up of nine of 13 eyes treated by therapeutic keratoplasty for suppurative keratitis is described. One of the thirteen cases died three years after surgery and three were lost to follow-up. Two of the nine refused reoperation after early graft failure. Of the remaining seven, three had retained good functional visual acuity. Three of the penetrating keratoplasties required regrafting two to four years later, when conditions were less critical. Long-term results indicate that therapeutic keratoplasty may be an alternative modality for the management of suppurative keratitis with satisfactory long-term optical results.     

用深低温保存的角膜材料行板层角膜移植术治疗边缘性角膜变性

目的:探讨用深低温保存的角膜材料行板层角膜移植术治疗边缘性角膜变性的效果。方法:对角膜边缘已经很薄,接近穿孔或已经穿孔的27例边缘性角膜变性患者,用深低温保存的角膜材料行板层角膜移植术治疗,观察术后视力,眼压,植片愈合及并发症等情况,随访时间为2a。结果:术后角膜边缘病变均未发展,术后1wk视力基本与术前相同,1.0者11例,0.6～0.8者6例,0.3～0.5者8例,0.05～0.25者2例。原穿孔的病例有术后一过性高眼压、前房反应、瞳孔欠圆等并发症。2a内只有3例发生了术后排斥反应。结论:用深低温保存的角膜材料完全可以用来进行板层角膜移植治疗边缘性角膜变性,弥补了新鲜角膜的来源限制与时效限制,是治疗边缘性角膜变性的理想材料。     

'Hot' corneal grafts—a long-term study

Abstract
A six-year follow-up of nine of 13 eyes treated by therapeutic keratoplasty for suppurative keratitis is described. One of the thirteen cases died three years after surgery_-and three were lost to follow-up. Two of the nine refused reoperation after early graft failure. Of the remaining seven, three had retained good functional visual acuity. Three of the penetrating keratoplasties required regrafting two to four years later, when conditions were less critical. Long-term results indicate that therapeutic keratoplasty may be an alternative modality for the management of suppurative keratitis with satisfactory long-term optical results.     

Effect of hypothermic perfusion on corneal endothelial morphology.

The effect of moderate in-vivo hypothermic perfusion on corneal endothelial integrity was studied in the cat. Eleven cats underwent in-vivo anterior chamber perfusion for 30 minutes with either normothermic (23 degrees C) or hypothermic (5 degrees C) perfusate. Corneas were then evaluated clinically (biomicroscopy), functionally (vital staining), and morphologically (scanning electron microscopy) for changes attributable to hypothermic perfusion. All 3 modes of evaluation suggested no difference in corneal endothelial integrity under the 2 experimental perfusion conditions. At the clinical and scanning electron microscope levels hypothermic perfusion does not show any effects on the corneal endothelium. Regional hypothermia is of theoretical and potential utility in procedures involving prolonged intraocular perfusion.     

长期配戴角膜塑形镜对角膜厚度和角膜内皮细胞的影响

目的评价近视眼患者长期配戴角膜塑形镜对角膜厚度和角膜内皮细胞的影响。方法利用超声角膜测厚仪和非接触角膜内皮显微镜,测量和观察132名青少年近视眼患者（264只眼）配戴角膜塑形镜（透氧系数为100）前和戴镜期间的角膜中央和旁周边部的角膜厚度,以及角膜内皮细胞的密度和形态学改变。结果无论采用夜戴方式还是日戴方式配戴角膜塑形镜3年以上,角膜中央及旁周边部厚度均无明显改变（P〉0．05）,角膜内皮细胞密度均无明显降低（P〉0．05）,角膜内皮细胞平均面积和细胞变异系数均无明显增大（P〉0．05）,角膜内皮细胞六角形比率均无明显降低（P〉0．05）。结论利用高透氧材料的角膜塑形镜进行科学的角膜塑形治疗,对角膜代谢的影响轻微,长期配戴用于控制近视发展基本是安全的。     

The impact of corneal allograft rejection on the long-term outcome of corneal transplantation

PURPOSE: To examine the influence of corneal allograft rejection on the survival of penetrating corneal transplantation, to review the status of conventional therapies to improve graft survival, and to consider prospects for alternative approaches to reduce the impact of rejection. DESIGN: Perspective, including prospective, observational cohort study. METHODS: An examination of the literature on human corneal graft rejection and data from the Australian Corneal Graft Registry, reviewed in the context of clinical experience. RESULTS: Corneal graft outcome is not improving with era. The sequelae of inflammation, whether occurring before corneal transplantation or subsequently, exert a profound influence by predisposing the graft to rejection. Of the developments that have been instrumental in reducing rejection in vascularized organ transplantation, living-related donation is not an option for corneal transplantation. However, HLA matching may be beneficial and requires reassessment. The evidence base to support the use of systemic immunosuppressive agents in corneal transplantation is thin, and topical glucocorticosteroids remain the drugs of choice to prevent or reverse rejection episodes. Experimental approaches to local allospecific immunosuppression, including the use of antibody-based reagents and gene therapy, are being developed but may be difficult to translate from the laboratory bench to the clinic. CONCLUSIONS: Corneal allograft rejection remains a major cause of graft failure. High-level evidence to vindicate the use of a particular approach or treatment to prevent or treat corneal graft rejection is lacking. In the absence of extensive data from randomized, controlled clinical trials, corneal graft registers and extrapolation from experimental models provide some clinically useful information.     

深低温长期保存角膜移植

目的　探讨深低温长期保存角膜在临床角膜移植术中的应用价值。方法　应用深低温保存 2 0天～48(平均 2 3± 12 .6 )个月的角膜 42例 (4 3眼 )穿透性角膜移植术和 4例 (4眼 )板层角膜移植术。结果　术后随访 2～30 (平均 6 .6± 3.8)个月 ,角膜植片透明率 81.2 5 % ,视力显著提高。结论　深低温长期保存角膜具有较好的临床应用价值。     

长期低温保存角膜方法的建立和临床应用

目的探索简易安全的长期保存供体角膜方法,为临床提供优质角膜材料.方法建立简易深低温冻贮技术保存活性角膜材料和全眼球冷冻法、4℃甘油脱水法保存板层角膜移植材料.采用透射电镜和临床角膜移植术后随访观察对3种方法保存的角膜材料进行了评价.结果电镜检查所见深低温保存的角膜片,内皮细胞完整,仅见线粒体肿大.在维持支架完整方面,深低温冻法效果最佳,全眼球冷冻法优于4℃甘油脱水法.板层角膜移植术后1～6年随访,全眼球冷冻法保存的植片(n=40)透明率为67.5%,新生血管化为32.5%;4℃甘油脱水法(n=110)透明率61.8%,新生血管化37.3%.穿透性角膜移植和眼前节重建术后1～3年随访情况分别为,深低温保存的植片增视率75.4%、75%;透明率75.4%、75%;角膜厚度(mm)0.54±0.05、0.61±0.06;内皮细胞密度(细胞/mm2)1,035±245,949±312.结论简易深低温长期保存的角膜材料可用于穿透性角膜移植术.全眼球冷冻法可代替4℃甘油脱水法长期保存板层角膜移植材料,且方法更简便.     

Predicting endothelial cell loss and long-term corneal graft survival

PURPOSE: To evaluate a biexponential decay model for describing the loss of corneal endothelial cells with age as well as the increased loss of cells after cataract surgery and penetrating keratoplasty. METHODS: Data from previous studies were identified and the sum of two exponentials, d = p. exp(-at) + q. exp(-bt) (where d is cell density at time t, p and q are constants the sum of which is equal to the initial cell density, and a and b are exponential rate constants), fitted to each data set by a nonlinear least-squares algorithm. Goodness of fit was indicated by the residual standard deviation. Half times were calculated from the exponential rate constants. RESULTS: The model identified in each instance a rapid and a slow component to the cell loss. The half time for the slow component of the loss with age was 224 years, underlining the excess endothelial capacity in normal eyes. After surgery, the rapid component of the cell loss was probably due to surgical trauma and, after penetrating keratoplasty, cell-mediated rejection and other complications. The half times of the slow component were only 26 years after cataract surgery and 21 years after penetrating keratoplasty. DISCUSSION: The loss of endothelial cells followed a biexponential decay and could thus be described by a single equation. The half times of the slow component of the cell loss after surgery were substantially less than for the loss with age, indicating a markedly increased rate of cell loss that persisted for many years after surgery. A mechanism for this accelerated cell loss is suggested that involves a nonspecific, innate response initiated by the breakdown of the blood-ocular barrier. The model was used to calculate endothelial cell loss in the long term after penetrating keratoplasty and to predict when cell density would reach levels that are incompatible with maintenance of transparency and graft function. Thus, a rationale is presented for the setting of minimum donor cell densities by eye banks.     

Deep corneal stromal opacities in long-term contact lens wear

In 32 patients with long-term contact lens wear (up to 19 years), deep whitish opacities directly adjacent to Descemet's membrane were seen in the central part of the cornea. These opacities were seen in soft hydroxyethylmethacrylate (HEMA) as well as in hard (polymethylmethacrylate, PMMA) contact lens wear. These conditions could reduce visual acuity. When contact lens wear was discontinued or when the HEMA or PMMA lenses were replaced by gas-permeable rigid lenses, the lesions gradually diminished and resolved completely in most patients. One possible cause of these opacities is an allergic reaction to thimerosal. Another possible cause is chronic anoxia of the corneal stroma and endothelium. Endothelial cell density was not abnormal, but there was a marked polymegethism of the endothelium as a sign of endothelial stress.     

Isolation and long-term cultivation of human corneal endothelial cells

Human corneal endothelial cells (HCEC) were isolated by means of enzymatic treatment of excised corneas. The corneas were incubated for 1.5 hr together with a high concentration of collagenase (0.5%), followed by a long-term incubation (up to 16 hr) using a low concentration of the enzyme (0.04%). Endothelial cells were enriched against contaminating fibroblasts by using a selective L-valine-free medium which inhibited fibroblast growth during the first passages. Subcultures of HCEC were passaged for more than 20 generations without showing signs of senescence. Laminin and chondroitin sulfate functioned as a substrate for HCEC, promoting proliferation and allowing the cells to grow in monolayer formation. The inclusion of fibroblast growth factor (FGF) as well as chondroitin sulfate in the medium led to an additional increase in the rate of proliferation.     

A novel microscope system for time-lapse observation of corneal cells in a living mouse

A novel microscope system is presented for observation of corneal cells in a living mouse. It enables tracking of individual cells in all layers of the cornea at various times, thus allowing the generation of time-lapse recordings. The system consists of three major components: an upright fluorescence microscope for visualization of corneal cells, a mouse-holding unit for immobilization of the animal and the eye, and a set of gimbals which permit observation of a wide area of corneal surface without refocusing. The same cells could be observed at different limes with the help of fiducial marks in the cornea, allowing their changes in position to be determined under natural and experimental conditions. This technique should prove useful in investigation of the cell movement in normal and diseased corneas, including the study of wound healing after an injury or surgery.