外伤性白内障动物模型的制作探讨

目的　观察兔、狗、猫、大鼠等动物在晶状体创伤后白内障的形成情况,以选择一种可靠的外伤性白内障动物模型。方法　用针头刺穿动物角膜,并将晶状体前囊及皮质划开(兔、狗、猫的前囊约划开3mm×4mm大小,大鼠约1mm×1.5mm,均呈椭圆形),术后每日用裂隙灯显微镜检查术眼晶状体情况,30天时取晶状体标本作火棉胶切片光镜检查。结果　在晶状体创伤后兔、狗、猫仅形成晶状体创口局部的局限性浑浊,而大鼠则形成白内障。结论　制作外伤性白内障动物模型时,宜选用大鼠,而不宜选用兔、狗、猫等动物。     

光学相干断层扫描血管造影（OCTA）在异种角膜移植供体选择中的应用研究

目的　利用光学相干断层扫描血管造影（optical coherence tomography angiography,OCTA）技术比较新西兰兔和猫角膜上皮、角膜全层厚度与人类的差别,探讨不同动物作为异种角膜移植实验模型的形态学依据。方法　雄性新西兰白兔和雄性猫各12只,分为A、B两组,每组各12只,OCTA技术测量每组样本双眼角膜上皮和角膜全层的厚度,所得数据以瞳孔为中心,根据距离角膜中央区的距离不同,利用系统软件将角膜划分为17个区域。中央区角膜是角膜正中间直径为2 mm的区域,内环和外环直径分别是5 mm和6 mm。在内外环分别又分出八个区域:上方（S）、鼻上（SN）、鼻侧（N）、鼻下（IN）、下方（I）、颞下（IT）、颞侧（T）、颞上（ST）,测量各区域角膜上皮和角膜全层厚度。比较新西兰兔和猫角膜上皮、角膜全层厚度与人类的差别。结果　猫角膜上皮和角膜全层厚度均大于兔。角膜厚度:猫角膜全层是中央薄、周边厚,其中在T5、ST5、S5、SN5、N5区与中央区的厚度差异均有统计学意义（均为P＜0.05）,角膜上皮在ST5、S5、SN5区与中央区厚度的差异均有统计学意义（均为P＜0.05）;兔角膜全层同样为中央薄、边缘厚,其中在T5、IT5、IN5、N5、T6、N6区与中央区厚度差异均有统计学意义（均为P＜0.05）,角膜上皮ST5、S5、SN5、ST6、S6、SN6区与中央区厚度差异均有统计学意义（均为P＜0.05）。与人类角膜相比,两种实验动物与人在角膜全层和角膜上皮厚度方面差异均有统计学意义（均为P＜0.05）。结论　猫角膜与人类角膜在角膜全层厚度和角膜上皮厚度及其分布方面具有相似的区域,同时,猫角膜全层厚度和角膜上皮厚度均较人类厚,这在异种角膜移植后的屈光调节中也具有优势。猫较兔更适合作为人类异种角膜移植的潜在供体。     

表层角膜镜片术动物模型的研究

建立了猴、兔、狗的表层角膜镜片术的动物模型，以猴的模型最成功。术眼进行了组织学检查，发现上皮厚度及角膜细胞正常。我们认为，建立表层角膜镜片术动物模型需考虑：供受体角膜组织结构、屈光参数、厚度和前弹力膜。     

血管内皮细胞替代角膜内皮细胞的可行性

目的:探讨培养的人脐静脉内皮细胞行猫眼角膜内皮细胞移植的可行性。方法:取第三代体外培养人脐静脉内皮细胞,种植在处理过的人羊膜上,待完全形成单层后用于细胞移植手术。正常健康家猫20只,分为A人脐静脉内皮细胞移植组:将载有完全融合的人脐静脉内皮细胞的羊膜移植到去除自体角膜内皮细胞及后弹力层的猫角膜上;B单纯羊膜移植对照组:将保存人羊膜移植到去除自体角膜内皮细胞及后弹力层的猫角膜上;C去除内皮细胞对照组:去除猫眼自体角膜内皮细胞及后弹力层后,既不移植羊膜,也不移植血管内皮细胞。术后1,2,4,8,12,24wk以裂隙灯观察角膜的透明度、眼前节炎症情况,同时行大体及裂隙灯照相。并以角膜厚度仪测量角膜厚度,A组在术后1,2,4,8wk各取1例植片制备光镜标本进行组织病理学检查。对照组均取术后2wk植片做光镜检查。结果:A组共11例植片术后3d水肿渐消退,植片渐透明,并在1wk内保持完全透明。4例在术后1～2wk因排斥反应而混浊,其中3例于混浊后4wk逐渐恢复透明,1例持续混浊。6例在术后12～24wk植片持续透明,光镜观察显示,移植的内皮细胞在前房内成连续单层排列。B组植片持续水肿混浊,但较C组轻,未见免疫排斥反应发生;2wk植片光镜观察羊膜与基质贴附较好无皱折。C植片持续高度水肿混浊,在长达24wk的观察中未发现恢复透明现象。2wk植片光镜观察完全没有后弹力层及内皮细胞层,基质高度水肿,结构疏松紊乱。结论:以人羊膜为载体移植的人脐静脉内皮细胞在前房环境内存活24wk,并可行使角膜内皮细胞的屏障及液泵功能。与角膜基质贴附紧密,不发生免疫排斥反应。     

中性粒细胞在不同品系正常小鼠角膜的分布及其与角膜创伤修复的关系

背景 以往人们通常认为角膜无血管、无髓系来源的免疫细胞存在.C57BL/6J小鼠、BALB/c小鼠和裸鼠是眼科免疫学基础研究的常用模型,这些小鼠的角膜是否存在天然免疫的关键细胞——中性粒细胞是值得关注的问题. 目的 研究实验室常用的C57BL/6J鼠、BALB/c鼠和裸鼠正常角膜的中性粒细胞分布特征及其与角膜创伤修复的关系,为相关研究提供依据. 方法 选取角膜正常、10 ～ 12周龄的SPF级雄性C57BL/6J鼠、BALB/c鼠和BALB/c背景的裸鼠各16只,取3种小鼠各8只制备成中央区相连的4瓣角膜铺片,并以角膜周边血管缘为界向内以3个同心圆分区.分别用Gr-1-FITC抗体和CD31/PECAM-1-PE抗体对角膜中性粒细胞和血管进行免疫荧光染色,用免疫荧光显微镜和AR软件测量角膜血管面积并计数中性粒细胞.选取3种小鼠各8只制备角膜创伤模型,用无菌手术刀片以角膜中央为中心做十字划痕,深度至角膜前弹力层.创伤后即刻（0 h）、12h、24 h用2 g/L荧光素钠点眼,荧光显微镜下以AR软件计算不同时间点的创伤面积.于划痕后24 h取小鼠角膜制备铺片,用Gr-1-FITC抗体和CD31/PECAM-1-PE抗体行荧光染色,比较3种创伤小鼠角膜的血管分布、中性粒细胞的数量和分布情况.实验动物的饲养与使用均遵循美国视觉与眼科研究协会制定的科研动物使用规范. 结果 正常C57BL/6J小鼠、BALB/c小鼠和裸鼠角膜中性粒细胞总数分别为（1 733±237）、（353±96）和（1 601 ±223）个/角膜,BALB/c小鼠角膜中性粒细胞数明显少于C57BL/6J小鼠和裸鼠,差异均有统计学意义（P＜0.01）.3种正常小鼠角膜缘均可见血管分布,BALB/c小鼠角膜缘血管面积明显小于C57BL/6J小鼠和裸鼠,C57BL/6J小鼠角膜缘血管面积明显大于裸鼠,差异均有统计学意义（P＜0.01）.3种正常小鼠中性粒细胞的数量与血管面积均呈明显正相关（C57BL/6J：r=0.936,P=0.001;BALB/c：r =0.939,P=0.001;     

微型角膜刀制作超薄角膜瓣的实验研究

目的研究KM_5000D微型角膜刀制作超薄角膜瓣的技术。方法设计制作超薄角膜瓣的自动旋转型KM_5000D微型角膜刀成形系统包括微型切割器、双电机动力装置和控制箱部件。以此成形系统对新鲜离体猪眼80眼、离体人眼10眼和在体兔眼12眼进行超薄角膜瓣的制作,观察运刀情况,角膜瓣厚度、直径以及瓣异常的发生率;离体人眼角膜瓣标本在光镜和扫描电镜下观察切面和边缘形态。结果实验中,负压保持眼压稳定在65 mmHg。离体猪眼角膜瓣厚度和直径分别为(87.85±4.64)μm和(8.8±0.42)mm,瓣异常发生率18.75%。离体人眼角膜瓣厚度和直径分别为(86.4±5.13)μm和(7.5±0.55)mm,瓣异常发生率20%。在体兔角膜瓣厚度和直径分别为(62.08±3.70)μm和(7.96±0.30)mm,瓣异常发生率16.67%。离体猪眼、离体人眼和在体兔眼的运刀顺畅比率分别为88.75%,80.0%和83.33%。离体人眼角膜瓣光镜检查显示其保持了角膜上皮、前弹力层和前部少许基质,扫描电镜检测显示切面光滑度和边缘整齐性良好。结论KM_5000D微型角膜刀制作超薄角膜瓣安全有效,预测性、稳定性良好。可应用于超薄角膜瓣LASIK手术的临床研究。     

体外兔胚胎成纤维细胞为饲养层克隆兔角膜缘干细胞

目的研究兔胚胎成纤维细胞体外克隆兔角膜缘干细胞。方法兔胚胎成纤维细胞经丝裂霉素C(MMC)处理成饲细胞,用消化法培养兔角膜缘基底层细胞并接种于含有经MMC处理饲细胞的12孔培养板,进行原代培养。观察其光镜特征、电镜结构,用间接免疫细胞化学染色等对克隆的细胞进行综合鉴别。结果克隆的细胞呈典型的上皮细胞形态,电镜下可见微绒毛、桥粒、张力丝等典型上皮细胞结构,单克隆抗体AE1、PCNA染色后细胞大多数阳性,单克隆抗体AE5染色后细胞染色偶见阳性。结论体外兔胚胎成纤维细胞为饲养层成功地克隆出兔角膜缘干细胞。     

人角膜Bowman层的结构观察

目的 通过光镜与电镜观察人角膜,Bowman层(Bowman'slayer BL)的超微结构,并精确测量其厚度.方法 应用常规方法将角膜片制成石蜡切片和超薄切片,分别在光镜和电镜下观察BL的超微结构,并测量其厚度.结果 BL位于上皮基底膜和基质层之间,在光镜下为一层相当均匀的非细胞层,在电镜下可见其主要由排列不规则的胶原纤维所组成.测得平均厚度为(10.61±1.22)μm.其中男性(10.65±1.30)μm,女性(10.56±1.20)μm.结论 BL是人角膜的共有结构,其厚度为(10.61±1.22)μm.     

脱水保存角膜基质为载体培养角膜内皮细胞的实验研究

目的探讨以脱水保存角膜基质/后弹力层为载体培养角膜内皮细胞,构建组织工程化角膜内皮细胞移植膜的可行性及其机理。设计实验性研究。研究对象体外培养的兔角膜内皮细胞和脱水保存角膜基质/后弹力层。方法兔角膜经中性蛋白酶37°C孵育5min,去除内皮细胞保留后弹力层和角膜基质,无水氯化钙脱水后低温保存,使用前磷酸盐缓冲液复水。纯化的角膜内皮细胞接种于基质载体的后弹力层上进行体外培养,直至生长融合为细胞单层,倒置显微镜下观察细胞形态学变化。在不同时间点(1、2、4、6d)收集植片进行HE染色和电镜检测,分析组织结构的变化。主要指标角膜内皮细胞在脱水保存角膜基质/后弹力层载体上形成单层时间和生长特性,组织工程化角膜内皮细胞移植膜的三维结构和超微结构。结果角膜内皮细胞在载体上快速贴壁生长并增殖,体外培养6～7d即融合成单层,复合角膜内皮组织由基质/后弹力层和单层扁平内皮细胞组成,与生理状态下的角膜内皮组织相近。电镜下组织培养的兔角膜内皮细胞间连接紧密,细胞为多边形,胞核清晰,具有正常兔角膜内皮细胞的超微结构。结论角膜内皮细胞能够在干燥脱水保存基质/后弹力层载体上良好生长,并形成形态结构与正常角膜内皮组织相似的细胞单层,为角膜内皮细胞移植提供了新的载体选择。(眼科,2006,15:164-168)     

三种实验动物角膜活体共焦显微镜检测的比较解剖学研究

背景 海德堡视网膜厚度分析仪和角膜模块的结合实现了对眼表活体组织结构的非侵入性检查,利用共焦显微镜对常用实验动物角膜结构进行比较研究可为相关研究提供依据.目的 利用活体共焦显微镜比较新西兰大白兔、Lewis大鼠、Swiss小鼠的角膜结构,建立实验动物角膜的活体组织图像资料,为共焦显微镜的实验研究提供依据.方法 利用海德堡视网膜厚度分析仪(HRT-Ⅱ)的Rostock角膜模块对新西兰大白兔、Lewis大鼠、Swiss小鼠的角膜进行活体分析,角膜的每一层各采集20张共焦显微镜图片,比较分析实验动物角膜各层的形态学特点及角膜内皮细胞密度.结果 共焦显微镜下3种实验动物角膜表层上皮细胞表现为高反光或低反光的多形细胞,基底上皮细胞表现为暗的细胞质,细胞核不可见,细胞间排列紧密、规则；前弹力层均表现为含有丰富上皮下神经丛的无定形物质.兔角膜基质层在黑色背景中散布着高反光物质,即为角膜基质细胞核,后基质层细胞密度高于前基质层；大鼠和小鼠的角膜基质层仅观察到大量反光的星形结构,无明显的细胞核.3种实验动物的角膜内皮细胞形态相似,均表现为高反光的胞体,边界较暗且细胞排列成蜂窝状.新西兰兔前基质角膜细胞密度中位数为387.5个/mm2,后基质角膜细胞密度中位数为223.5个/mm2,明显少于前基质的细胞密度(U=0.000,P=0.000)；新西兰兔、Lewis大鼠、Swiss小鼠角膜内皮细胞密度中位数分别为2192.5、1936.0、1565.0个/mm2,总体差异有统计学意义(H=49.940,P=0.000),兔角膜内皮细胞密度明显高于大鼠和小鼠,差异均有统计学意义(x2=0.000,P=0.000；x2=0.000,P=0.000),大鼠和小鼠的角膜内皮细胞密度差异亦有统计学意义(x2=0.000,P=0.000).结论 共焦显微镜下新西兰大白兔、Lewis大鼠、Swiss小鼠角膜各层的细胞形态相似,但内皮细胞密度和基质细胞形态之间存在明显差异.HRT-Ⅱ的Rostock角膜模块可为动物实验提供角膜各层次的高分辨率图像.     

The alterations in corneal structure at III/IV stage of keratoconus by means of confocal microscopy and ultrasound biomicroscopy before penetrating keratoplasty

PURPOSE: The aim of the study was in-real time observation and morphological evaluation of the human corneas at III/IV stage of keratoconus, using the scanning slit confocal microscope Confoscan P4 and ultrasound biomicroscopy--UBM. MATERIAL AND METHODS: The patients with keratoconus were examined according to the Amsler scale. The material consisted of 12 corneas of 11 patients (8 men, 3 women), where assessment of the corneal structure was performed with the confocal microscope ConfoScan P4 (Tomey) and ultrasound biomicroscopy--UBM Model 840 (Humphrey Instruments). The comparison of different corneal regions (central and peripheral) was evaluated. RESULTS: The confocal microscopy and UBM revealed thinning of the layers of the corneal structure and pathological changes in the central area, especially at IV stage of keratoconus. The desquamating superficial cells were elongated, arranged around the apex of the cornea. Below the Bowman's membrane a considerable disarrangement of collagen fibers reflected by bright background illumination was observed. In the posterior part of the stroma the folds were detected. The examination of the cornea showed thickening in the peripheral part, central detachment of the Descemet's membrane and the endothelium from the posterior surface of the cornea. The thickness of the cornea varied from 0.201 to 0.384 mm in the central part and 0.675 to 0.740 mm in the peripheral area. CONCLUSION: Confocal scanning microscopy combined with ultrasound biomicroscopy enables the cornea to be examined in vivo. It can be used to localize pathological changes in individual corneal layers and to assess their extent.     

CD8+ T cell-mediated delayed rejection of orthotopic guinea pig cornea grafts in mice deficient in CD4+ T cells

PURPOSE: To determine the immunopathogenesis of delayed orthotopic corneal xenograft rejection in mice deficient in the xenoreactive CD4+ T cells that mediate acute rejection. METHODS: CB.17 SCID and BALB/c mice were used as recipients of orthotopic cornea grafts obtained from strain 13 guinea pigs. Before transplantation, SCID recipients, which do not normally reject guinea pig cornea grafts, were reconstituted with spleen cells (whole, CD4-depleted, CD4/CD8-depleted) or purified CD8+ T cells from normal BALB/c donors. Graft survival was assessed by clinical examination, and median survival times (MST) were calculated. Lymphocytes from mice that rejected guinea pig cornea grafts were analyzed in vitro for their capacity to respond to guinea pig xenoantigens and to lyse guinea pig target cells. RESULTS: SCID mice reconstituted with whole spleen cells from BALB/c donors rejected guinea pig corneas with a vigor identical with that of normal BALB/c mice (MST = 15 and 14 days, respectively), whereas SCID mice reconstituted with CD4-depleted BALB/c spleen cells rejected guinea pig corneas in a delayed fashion (MST = 27 days), as did SCID mice reconstituted with purified CD8+ T cells from BALB/c donors. Although CD8+ T cells from rejector mice failed to lyse guinea pig target cells in vitro, the T cells proliferated and secreted IFN-gamma in response to in vitro stimulation with guinea pig xenoantigens. CONCLUSIONS: Guinea pig cornea xenografts that avoid acute rejection in CD4+ T cell-depleted mice are vulnerable to rejection by CD8+ T cells. Effector CD8+ T cells destroy corneal xenografts through release of proinflammatory mediators (IFN-gamma) rather than by cytotoxicity.     

Histology and transmission electron microscopy of the cornea in xeroderma pigmentosum type C

Xeroderma pigmentosum is a very rare precancerous skin disease that is triggered by sunlight. It is caused by a defect in the DNA repair system and causes benign and malignant transformations. Only eye tissues that come into contact with UV light are affected, such as the lids, conjunctiva and cornea. We describe a patient who suffered from xeroderma pigmentosum type C, showing the typical skin alterations but no sign of malignancy. A perforating keratoplasty was performed on both eyes because of the dense opacity of the corneas. The corneal buttons obtained were examined by light and transmission electron microscopy. Degeneration was found only in the basal-cell layer of the corneal epithelium. The most severe morphological changes were seen in Bowman's layer, the subepithelial stroma, Descemet's membrane and the corneal epithelium. Bowman's layer was often interrupted or replaced by a degenerative pannus, which extended into the underlaying stroma. Subepithelial channels were localized in the basal epithelium and protruded into the subepithelial stroma. In both corneas, Descemet's membrane contained different amounts of so-called lattice collagen, and the remaining endothelial cells in the left cornea contained numerous melanin granules. Offprint requests to: E.-M. Haller     

Depth and age-dependent distribution of keratocytes in healthy human corneas: a study using scanning-slit confocal microscopy in vivo

PURPOSE: To document keratocyte distribution and changes with age in the cellular network of the human cornea in vivo. SETTING: Department of Ophthalmology, University of Rostock, Rostock, Germany. METHODS: Forty-nine eyes of 31 healthy subjects of various ages were examined with a modified Microphthal scanning-slit confocal microscope (SSCM) (Hund) to document keratocyte distribution in the intact living cornea. Optical sections made by confocal microscopy were recorded on videotape, and the keratocyte density was determined for the total volume of the cornea and for the stromal sublayers. RESULTS: The highest cell density was in the anterior stroma of the cornea immediately posterior to Bowman's membrane (24 320 cells/mm(3) +/- 6740 [SD]), the lowest in the central area (11,610 +/- 4290 cells/mm(3)), and an intermediate density in the posterior stroma immediately adjacent to Descemet's membrane (18,850 +/- 4610 cells/mm(3)). The differences were statistically significant (P <.005). The keratocyte density was significantly lower in the anterior and posterior regions in the group older than 50 years: Cell density at 4% depth was 20,960 +/- 8200 cells/mm(3) and at 96%, 15 520 +/- 4290 cells/mm(3) (P <.05). CONCLUSIONS: In healthy living corneas, the keratocyte density was high in the areas adjacent to Bowman's and Descemet's membranes and was lower in patients older than 50 years than in those younger than 50 years. Further studies are needed to document the rate of change with age and to better understand the role and capacity of aging keratocytes in regenerative processes following corneal diseases or surgical procedures.     

Serum albumin in mammalian cornea: implications for clinical application

PURPOSE: To compare the abundance and spatial distribution of serum albumin in the mouse and bovine cornea. METHODS: Serum albumin from cornea was separated from transketolase by SDS-PAGE (+/-dithiothreitol [DTT]) and identified by peptide sequencing and immunoblot analyses. The fractional content of serum albumin was determined in water-soluble extracts of cornea by imaging analyses after SDS-PAGE. Serum albumin was localized in cornea by immunohistochemistry and by SDS-PAGE analyses of samples from separated epithelium and stroma. RESULTS: SDS-PAGE (-DTT) resolved mouse serum albumin and transketolase and indicated that serum albumin was 13% of the water-soluble protein in whole mouse corneas. By contrast, corneal epithelial fractions contained little (<1%) serum albumin. Immunohistochemistry indicated that mouse serum albumin was present throughout the stroma between collagen lamellae. Immunohistochemical analyses of bovine cornea yielded similar results. In addition, immunohistochemistry for serum albumin revealed positive staining in a small number of basal epithelial cells next to Bowman's membrane, and greater staining in the anterior-peripheral stroma as well as immediately adjacent to Descemet's membrane. CONCLUSIONS: Mouse and bovine cornea have a similar content and spatial distribution of serum albumin. The appreciable serum albumin in the cornea documented here and elsewhere raise the possibility that it contributes to the physiological or optical functions of the cornea. Moreover, serum albumin's ability to bind drugs suggests that mice corneas could be exploited to study drug-serum albumin interactions in vivo and to test the usefulness of serum albumin as a drug carrier for corneal disorders.     

Report of a new family with dominant congenital heredity stromal dystrophy of the cornea.

PURPOSE: To report a new family with the rare form of congenital and hereditary stromal dystrophy of the cornea. METHODS: A mother and son, showing a bilateral congenital clouding of the cornea, were studied clinically and by biomicroscopy. After corneal transplantation, light microscopy and electron microscopy were performed. RESULTS: The stroma of the cornea was bilaterally and symmetrically thickened with diffuse and homogeneous small opacities. The opacities were present at birth and slowly progressive. Visual acuity was reduced to 2/10. Electron microscopy of the excised corneas showed a thickened stroma owing to cleaving of the lamellae by alternating layers of small-diameter collagen fibrils arranged in a random fashion. The epithelium, Bowman's membrane, the endothelium, and Descemet's membrane were normal. CONCLUSIONS: This family presents with a congenital stromal dystrophy of the cornea not linked to endothelial defects and thus differs from the more common form of congenital hereditary corneal endothelial dystrophy.     

Heterotopic corneal grafting in mice: a new approach to the study of corneal alloimmunity

Heterotopic grafting of murine corneas to the thoracic cage of recipient mice affords an opportunity to study the alloimmune rejection process in this well-characterized laboratory species. Immune rejection of cornea allografts can be reliably identified by direct visual, slit-lamp, and histologic observations. Virtually intact syngeneic corneal epithelium and stroma survive at the heterotopic site for at least 21 days. Allogeneic corneal epithelium is destroyed by an intense fibrovascular infiltrative process. If Descemet's membrane is preserved, integrity of the stroma and epithelium of syngeneic corneal grafts is preserved, whereas when this membrane is broken, progressive stromal deterioration sets in. This property of Descemet's membrane is particularly apparent in allogeneic corneal grafts.     

Inherited corneal opacifications with an unusual distribution

PURPOSE: To describe corneal opacities of a new type and distribution in a small family. METHODS: Family members were interviewed and examined to establish a pedigree and to detect any corneal abnormalities. RESULTS: Two family members presented with corneal opacities. Both had, in the very peripheral cornea, flat, greyish, rounded opacities, 20-200 microm in diameter, on the Descemet's membrane. In addition, the mother had the same type of opacities over the central cornea just inside the Bowman's layer. The remaining parts of the corneas were clear. Vision was unaffected and the opacities caused no discomfort. There was no other corneal pathology. The subjects' general health was good. CONCLUSIONS: To our knowledge, these types and distribution of corneal opacities have not been described previously. Although the mode of inheritance at this point is uncertain, we believe the changes are of a dystrophic nature.     

The swelling of cornea in bank cultivation. The role of barriers and peripheral edge.

The swelling of a rabbit cornea in organ culture is caused by influx of fluid via the surface. Data regarding the weight increase rates during the first 4 h of corneal buttons with different diameters, have been used to calculate the net influx per mm2 per h via the anterior + posterior surfaces on one hand, and via the peripheral edge on the other hand. In fresh corneas the contribution to the corneal swelling, of the net fluid uptake via the anterior + the posterior surfaces, is negligible. The influx via the peripheral edge is about the same in fresh and freeze treated buttons. For freeze treated corneas, the resistance for fluid transport via the anterior + posterior surfaces seems to be 4 times higher than the resistance for transport via the peripheral edge. This result indicates that the Descemet's membrane and the Bowman's layer may have some barrier effect. An alternative or supplementary explanation is that, at least in swollen corneas, there may be reduced resistance to fluid flow along the corneal plane as compared with the flow vertical to this plane.