Pseudophakic bullous keratopathy. Relationship to preoperative corneal endothelial status

Pseudophakic bullous keratopathy is one of the complications of intraocular lens implantation. A knowledge of the preoperative status of corneal endothelium may help to minimize the incidence of this complication. The preoperative corneal endothelial status of 118 eyes of 102 patients who received Worst-Medallion intraocular lenses more than five years ago was analyzed retrospectively. This data was then correlated with the postoperative clinical status of the cornea. Twelve eyes (10%) underwent penetrating keratoplasty for irreversible corneal edema, and 28 of the remaining eyes (22%) had clinical evidence of peripheral corneal edema. No correlation was found between the preoperative endothelial cell density or the degree of postoperative cell loss and the development of corneal edema. Significant correlation was found between variation in cell size (pleomorphism) and the development of postoperative corneal edema. Greater density of precipitates on endothelium and abnormality in cell shape postoperatively were also frequently seen in corneas that developed edema subsequently.     

Cytochrome oxidase activity of Fuchs' endothelial dystrophy

The normal human corneal endothelial monolayer maintains stromal water equilibrium and thus, transparency, by means of a pump-leak mechanism. Water leaks into the stroma through non-tight lateral cell junctional complexes and is drawn out by an energy dependent cell membrane ion pump. We investigated the histochemical localization of cytochrome oxidase activity (CO), an important energy-deriving mitochondrial enzyme in dysfunctional corneas with Fuchs' endothelial dystrophy (ED), which is a regionally distributed disease. Keratoconus corneas were used as controls for functional control endothelium. In the central area of the corneal button, decreased CO activity was demonstrated which correlated clinically with central corneal edema. This reflects decreased metabolic activity and/or decreased numbers of mitochondria in the attenuated dysfunctional cells. In the mid-periphery, CO activity was increased in the cellular rosettes surrounding guttata, which may be related to increased synthesis of abnormal Descemet's membrane and guttata. Peripherally, the large polygonal cells resembled functional endothelium in their morphology and CO activity. We have, therefore, demonstrated regional differences in energy metabolism in endothelium from Fuchs' ED patients which may be related to decreased numbers of mitochondria in the dysfunctional cells, and/or to synthesis of abnormal Descemet's membrane material.     

Corneal endothelial integrity in mice lacking extracellular superoxide dismutase.

PURPOSE: To evaluate corneal endothelial morphology in mice without secreted extracellular superoxide dismutase (SOD) in normal ageing and in a lipopolysaccharide (LPS)-induced inflammation model and to measure the contents of SOD isoenzymes in the mouse cornea and the superoxide radical concentrations in corneas with and without extracellular SOD. METHODS: The central corneal endothelium of wild-type and extracellular SOD-null mice were studied in micrographs at eight different ages and after a unilateral intravitreal injection of LPS, with the contralateral eye serving as the control. The activities of the SOD isoenzymes in the mouse cornea were determined with a direct assay, the superoxide radical concentration was assessed by lucigenin-induced chemiluminescence, and the extracellular SOD distribution was mapped with immunohistochemistry. RESULTS: The activities of the cytosolic Cu- and Zn-containing SOD, the mitochondrial Mn-containing SOD and extracellular SOD were 4300, 15, and 340 U/g wet weight, respectively. Extracellular SOD was found in the epithelium, stroma, and endothelium. The concentration of extracellular superoxide radicals was doubled in extracellular SOD-null corneas, and the endothelial cell density decreased more with age in extracellular SOD-null than in wild-type control corneas. In the LPS-induced inflammation model, the cell density decreased more, and the cells became more irregular in extracellular SOD-null than in wild-type corneas. CONCLUSIONS: In the mouse cornea, absence of extracellular SOD leads to a higher concentration of extracellular superoxide radicals, an enhancement in the spontaneous age-related loss of endothelial cells, and an increased susceptibility to acute inflammatory endothelial damage. Extracellular SOD is likely to have a protective role in the corneal endothelium.     

Posterior polymorphous dystrophy and LASIK

OBJECTIVE/METHOD: A 50-year-old hyperopic woman requested information about refractive surgery. Vesicle and band lesions at Descemet's membrane and endothelium were suggestive of posterior polymorphous dystrophy (PPD). Lower than normal endothelial cell densities were detected. A corneal refractive procedure was not recommended in this case. RESULTS/CONCLUSIONS: The presence of vesicles and bands at Descemet's membrane and endothelium is suggestive of PPD. Specular microscopy is mandatory in such patients, although corneal decompensation is not evident. A low endothelial cell count may be a contraindication for a hyperopic LASIK procedure in cases of PPD because of the possible risk of corneal decompensation.     

Pathogenic Role of Endoplasmic Reticulum Stress in Diabetic Corneal Endothelial Dysfunction

PurposeProgressive corneal edema and endothelial cell loss represent the major corneal complications observed in diabetic patients after intraocular surgery. However, the underlying pathogenesis and potential treatment remain incompletely understood.MethodsWe used streptozotocin-induced type 1 diabetic mice and db/db type 2 diabetic mice as diabetic animal models. These mice were treated with the endoplasmic reticulum (ER) stress agonist thapsigargin; 60-mmHg intraocular pressure (IOP) with the ER stress antagonist 4-phenylbutyric acid (4-PBA); mitochondria-targeted antioxidant SkQ1; or reactive oxygen species scavenger N-acetyl-l-cysteine (NAC). Corneal thickness and endothelial cell density were measured before and after treatment. Human corneal endothelial cells were treated with high glucose with or without 4-PBA. The expression of corneal endothelial- and ER stress–related genes was detected by western blot and immunofluorescence staining. Mitochondrial bioenergetics were measured with an Agilent Seahorse XFp Analyzer.ResultsIn diabetic mice, the appearance of ER stress preceded morphological changes in the corneal endothelium. The persistent ER stress directly caused corneal edema and endothelial cell loss in normal mice. Pharmacological inhibition of ER stress was sufficient to mitigate corneal edema and endothelial cell loss in both diabetic mice after high IOP treatment. Mechanistically, inhibiting ER stress ameliorated the hyperglycemia-induced mitochondrial bioenergetic deficits and improved the barrier and pump functional recovery of the corneal endothelium. When compared with NAC, 4-PBA and SkQ1 exhibited better improvement of corneal edema and endothelial cell loss in diabetic mice.ConclusionsHyperglycemia-induced ER stress contributes to the dysfunction of diabetic corneal endothelium, and inhibiting ER stress may offer therapeutic potential by improving mitochondrial bioenergetics.     

超声乳化术对伴有糖尿病的白内障患者角膜内皮的影响

目的：观察伴有糖尿病的白内障患者与单纯白内障患者在超声乳化术后角膜内皮的变化情况。

方法：选取2016-10/2017-06在广西壮族自治区人民医院确诊的白内障(cataract)患者78例92眼,按照有无糖尿病分为糖尿病组与非糖尿病组,其中糖尿病组40例44眼,非糖尿病组38例48眼。所有患者均由同一经验丰富的眼科医师行白内障超声乳化术联合人工晶状体植入术,分别于术前,术后1、4、8wk采用非接触式角膜内皮计数仪检测角膜内皮细胞密度(corneal endothelial density,CED)、六角形细胞比例(hexagonal cell percentage,HCR)、变异系数(variation coefficients,CV)、中央角膜厚度(central corneal thickness,CCT)。利用共焦显微镜记录术前、术后4、8wk的角膜内皮细胞形态。分别观察两组术中虹膜松弛综合征的发生情况。

结果：糖尿病组与非糖尿病组术前比较,角膜内皮六角形细胞比例降低,变异系数增大,差异均有统计学意义(P<0.05),角膜内皮细胞密度及中央角膜厚度差异均无统计学意义(P>0.05); 糖尿病组与非糖尿病组术后不同时间点相比较,六边形细胞比例减低,变异系数增大,差异均有统计学意义(P<0.05),角膜内皮细胞密度及中央角膜厚度差异均无统计学意义(P>0.05); 两组术后1、4、8wk的角膜内皮细胞密度及六角形细胞比例相较于术前均明显降低,变异系数相较于术前明显增高,差异均有统计学意义(P<0.05),术后1wk的中央角膜厚度相较于术前明显增厚,差异有统计学意义(P<0.05),而术后4、8wk与术前相比无统计学意义(P>0.05); 糖尿病组与非糖尿病组术前、术后4、8wk的角膜内皮细胞形态比较,术前糖尿病组角膜内皮细胞形态异型性较大,胞体大小不一,术后4wk糖尿病组的内皮细胞多形性增多,胞体大小各异,可见较大细胞核,术后8wk糖尿病组恢复较慢,仍可见不规则的内皮细胞及尚大的细胞核。糖尿病组术中虹膜松弛综合征的发生率为14%,非糖尿病组发生率为0。

结论：糖尿病及超声乳化术都会对角膜内皮细胞造成损害,同时超声乳化术对糖尿病患者的角膜内皮细胞形态影响较大且恢复较慢。糖尿病可能与虹膜松弛综合征的发生有关。     

Non-invasive assessment of the donor corneal endothelium using ocular redox fluorometry.

AIMS: To investigate the usefulness of ocular redox fluorometry for evaluating donor corneal endothelial viability. METHODS: Corneas from 42 recipients of penetrating keratoplasty and four donor corneas were examined by ocular redox fluorometry. Autofluorescence from reduced pyridine nucleotides (PN) and oxidised flavoproteins (Fp) of the human corneal endothelium were measured non-invasively, and the PN/Fp ratio was used as a tissue metabolic indicator. Specular microscopy and electron microscopy were also performed. RESULTS: Both the quality of specular microscopic image and the PN/Fp ratio were significantly correlated with the degree of corneal endothelial damage determined by histological examination. Corneas with poor specular microscopic image showed significantly decreased PN/Fp ratio compared with corneas with good or fair specular images (p = 0.041 and 0.027, respectively). The PN/Fp ratio increased in corneas with mildly damaged endothelium but decreased in corneas with severely damaged endothelium determined by histological examination. Evaluation of corneal endothelium by combination of specular microscopy and ocular redox fluorometry showed excellent association with that of histopathological examination (p < 0.0001). CONCLUSION: Ocular redox fluorometry is useful for assessing donor corneal endothelial viability. Combination of ocular redox fluorometry and specular microscopy may increase the ability of donor cornea selection.     

Regeneration of cat corneal endothelium induced in vivo by fibroblast growth factor

The corneal endothelium of man, primates and carnivores has limited regenerative ability. Fibroblast growth factor (FGF) stimulates the proliferation of various mesoderm-derived cells, including corneal endothelial cells, in vitro. In the present work the effect of FGF on the regeneration of injured cat endothelium in vivo was studied. Scraping of cat corneal endothelium off Descemet's membrane was carried out by a specially designed instrument. FGF from crude preparations (25 micrograms in 50 microliter saline) or affinity purified FGF (0.5 micrograms in 25 microliter saline) were injected immediately after the scraping of the endothelium, and in both cases significant stimulation of endothelium regeneration was observed. During the first 2 weeks after scraping, the endothelial cell density (ECD) in FGF-treated eyes was higher by a factor of 1.7-2.3 than that in the control eyes. This marked difference decreased with time, but even after 12 weeks the ECD in FGF-treated eyes was higher by a factor of 1.15-1.30 than in the control eyes. Furthermore, FGF improved the polygonal shape of the cells and decreased the corneal thickness. These results clearly demonstrate the efficacy of FGF in inducing the proliferation of cat corneal endothelial cells in vivo and indicate its potential application in clinical practice.     

硅油对角膜内皮的影响

目的：探讨硅油在不同情况下对角膜内皮的影响。方法;对１７０只眼行不同手术术前,术后２周,４周,８周及３个月时的角膜内皮细胞密度进行观察记录,同时对硅油人前房的２０只眼进行观察。结果;在眼压控制良好的情况下,有晶体眼行单纯玻璃体和切割术及玻璃体切割硅的填充术,无晶体眼行玻璃体切割硅油填充术。有晶体眼及无晶体眼行硅油取出术手术后各期内皮细胞密度与术前相比均无显著差异,有晶体眼行玻璃体切割晶体切割硅油填     

m4-muskarinerge Rezeptoren der Hornhaut

Background

Muscarinic cholinoceptors have been found in all types of ocular tissue, e.g. in corneal epithelium and endothelium. Latest research has focused only on the m5 cholinoceptor subtype. However, previous studies have also indicated the presence of m2 or m4 receptor subtypes in corneal tissue. The aim of this study was to show the decrease of intracellular cAMP formation and protein kinase A (PKA) activity after stimulation of m2 or m4 cholinoceptors in bovine corneal epithelial and endothelial cells.

Materials und methods

Muscarinic cholinoceptors were studied using polyclonal antibodies. The cAMP concentration was determined with an enzyme immunoassay and PKA activity was estimated by the consumption of ATP.

Results

Immunocytochemistry, immunofluorescence and immunoblotting revealed the presence of the m4 muscarinic cholinoceptor subtype but not of the m2 receptor subtype in bovine corneal epithelial and endothelial cells. In bovine corneal epithelium and endothelium protein cAMP formation was decreased and PKA activity was inhibited by acetylcholine in a dose-dependent manner (p<0.001).

Conclusion

The findings indicate that stimulation of m4 muscarinic cholinoceptors inhibits the cAMP-PKA pathway in corneal epithelial and endothelial cells resulting in decreased protein kinase A activity. Further work will be needed to clarify the physiological role of this signaling pathway in corneal epithelium and endothelium.     

A case of noninflammatory corneal edema following anterior-posterior radial keratotomy successfully treated by topical steroids

BACKGROUND: Corticosteroids seems to affect the functions of corneal endothelial cells directly in addition to its anti-inflammatory effect. CASE: A 69-year-old male presented with left blurred vision and decreased visual acuity in both eyes. He had undergone anterior-posterior radial keratotomy for myopia in both eyes 40 years before. Both eyes showed mild corneal stromal edema in the pupil area. We diagnosed the condition as corneal edema secondary to cell loss and dysfunction of corneal endothelium after surgery. The stromal edema further advanced in the left eye one month later. The corneal thickness increased from the initial value of 619 to 631 microns. The corrected visual acuity decreased from 0.5 to 0.06. There were no signs suggesting inflammatory reaction. The left eye was then treated with topical corticosteroids as eye-drops and by subconjunctival injection. The corneal thickness decreased to 546 microns two months later with improvement of visual acuity to 0.5. CONCLUSION: This case illustrates that topical corticosteroids may be effective for corneal edema through their anti-inflammatory effect and possible activation of the endothelium.     

Corneal endothelial changes and aqueous flare intensity in pseudoexfoliation syndrome

Purpose: To determine the changes of corneal endothelium in pseudoexfoliation (PEX) syndrome and the relations between their changes and aqueous flare intensity. Methods: 26 eyes with PEX syndrome, 17 clinically unaffected fellow eyes and 27 normal age-matched eyes were studied. The corneal endothelium of the eyes was examined using a specular microscope, and the aqueous flare intensity of the eyes was measured using a laser flare cell meter. Results: The corneal endothelial density significantly decreased both in the eyes with PEX and in the clinically unaffected fellow eyes compared to the normal control eyes (p < 0.001, p < 0.01). The acqueous flare intensity significantly increased in PEX syndrome (p < 0.01). There was a significantly inverse correlation between the corneal endothelial cell density and the aqueous flare intensity in PEX. Conclusion: A decrease in corneal endothelial cells was quantitatively identified in PEX syndrome. This change might have a relationship with a disorder of the blood-aqueous barrier in this syndrome. Copyright Copyright 1999 S.Karger AG, Basel     

生长因子与角膜内皮细胞

角膜内皮细胞是维持角膜透明的关键细胞成分,角膜内皮细胞密度降低和形态异常可导致内皮细胞功能失代偿而降低视力。在伤口愈合过程中,生长因子可增加角膜内皮细胞密度槿刺激内皮细胞再生,促进伤口愈合。肽类生长因子影响着多种细胞生理过程,包括细胞增殖,分化,移行和存活。     

Clinical Investigations on the Corneal Endothelium

The normal level of the corneal thickness and hydration is maintained by the barrier function and active fluid pump of the corneal endothelium. Three methods are currently available for the clinical study of this cell layer: (1) endothelial dysfunction results in a corneal swelling, and measurement of the corneal thickness allows the degree of endothelial damage and its repair processes to be evaluated; (2) the state of the barrier function may be studied through determination of the endothelial permeability to fluorescein; and (3) the endothelium can be photographed by specular microscopy, and the cell density and cell size distribution can be studied by morphometric analyses. A follow-up study of the cell transformation after surgical trauma revealed that the human endothelium shows very little proliferative activity, and the damaged area is covered by migration of cells in the surrounding area. It appears that the traumatized endothelium loses cells at a faster rate than that seen in the normal aging process, and endothelial dysfunction may develop many years after injury.     

Mitochondrial Superoxide Anion Overproduction in Tet-mev-1 Transgenic Mice Accelerates Age-Dependent Corneal Cell Dysfunctions

Purpose. The Tet-mev-1 mouse expressing a mitochondrial complex-II mutated SDHC(V69E) gene controlled by a tetracycline (Tet)-On/Off system can overproduce O(2)(·-) and is a versatile whole-animal model for studying mitochondrial oxidative stress. Here we report a series of age-dependent variations in corneal epithelium, endothelium, and parenchymal cells of the Tet-mev-1 mice relative to wild-type C57BL/6j mice. Methods. Measurements of (1) mitochondrial electron transport enzyme activities; (2) O(2)(·-) production; (3) carbonylated protein, and 8-hydroxydeoxyguanosine (8-OHdG) levels as markers of oxidative stress; (4) pathologic analyses under optical and electron microscopy; (5) hematoxylin-eosin or toluidine-blue staining; and (6) immunohistochemistry with an anti-β-catenin antibody were performed in the eye, especially the cornea. Results. Complex II-III activity was decreased by electron leakage between complex II and CoQ. This resulted in increased age-dependent intracellular oxidative stress in the eye of Tet-mev-1 mice. Corneal epithelialization was delayed in Tet-mev-1 mice after 20% ethanol treatment, as the number of cells and mitotic cells decreased in the corneal epithelium of Tet-mev-1 mice compared with that of wild type. The age-dependent decrease in cell number accelerated in the corneal endothelium cells. Moreover, it was suggested that the corneal thickness was decreased by thinning of parenchymal cells with age in Tet-mev-1 mice. Conclusions. These results suggest that mitochondrial oxidative stress with electron transport chain dysfunction can influence pathogenesis and progression of age-related corneal diseases, as well as generalized corneal aging acceleration.     

青少年近视患者配戴角膜塑形镜5年的有效性及安全性

目的　评价青少年近视患者长期配戴角膜塑形镜延缓近视进展的有效性及其对角膜的安全性。方法　回顾性病例系列观察研究。选取2012年1月至2013年12月于天津市眼科医院视光中心配戴角膜塑形镜且连续配戴5 a的153例（153眼）青少年近视患者，分别于戴镜前及戴镜后1 a、2 a、3 a、4 a、5 a采用裂隙灯显微镜评估角膜状态，采用光学生物测量仪检测眼轴长度，采用角膜内皮细胞计数仪测量中央角膜厚度、角膜内皮细胞密度、角膜内皮细胞面积、六边形细胞比例及角膜内皮细胞面积变异系数等，并对所得数据进行分析。结果　配戴角膜塑形镜前后裸眼视力及等效球镜度数差异均有统计学意义(F=442.515、415.389,均为P<0.001)。青少年近视患者配戴角膜塑形镜后眼轴增长速度平均为每年0.16 mm。戴镜5 a中，64眼(41.83％)发生不同程度的并发症，其中70.31％为1级或2级角膜点状染色。与戴镜前中央角膜厚度相比，戴镜后不同时间的中央角膜厚度均变薄，差异均有统计学意义（均为P<0.05）。与戴镜前相比，配戴角膜塑形镜5 a角膜内皮细胞密度及内皮细胞面积均无显著变化（F=0.328、0.735，均为P>0.05）；但六边形细胞比例显著降低（F=12.020，P<0.001），角膜内皮细胞面积变异系数显著增高（F=23.016，P<0.001）。结论　青少年近视患者长期配戴角膜塑形镜可获得良好的裸眼视力,且可有效延缓眼轴增长速度，长期戴镜未引起严重的角膜或结膜并发症,对角膜内皮细胞、中央角膜厚度影响均甚微。     

Contact lens-induced corneal endothelial polymegathism: functional significance and possible mechanisms

The corneal endothelium is principally responsible for maintenance of corneal deturgescence. Therefore, compromise of corneal endothelial functional integrity can result in corneal swelling and opacification. Contact lenses constitute a potential insult to the cornea because their wear reduces the oxygen available to that tissue. It has been reported that contact lens wear induces transient as well as permanent morphologic changes in the corneal endothelium. One of the permanent changes reported is referred to as polymegathism, which is a variation in cell size within the endothelial monolayer. Several investigators have suggested that polymegathism reflects a compromised endothelial functional status. Mechanisms proposed to explain contact lens-induced polymegathism include lactate accumulation, changes in pH, and elevation in CO2 content. We discuss these possibilities as well as speculate that these polymegathous shape changes may be a result of decreased endothelial ATP (adenosine triphosphate) levels and disturbed calcium homeostasis due to corneal endothelial hypoxia.     

Changes in nuclear DNA content and cell size of injured human corneal endothelium

To understand how human corneal endothelium compensates for cell loss, nuclear DNA-cytofluorometry and cell morphometry were carried out on injured corneal endothelium. The examined corneas included two cases of keratoconus complicated with acute hydrops and one without acute hydrops, two cases of herpetic keratitis, one case of post-intracapsular cataract extraction (post-ICCE) and one case of luetic keratitis. The endothelial cell layer was separated from Descemet's membrane and double-stained with Rhodamine-labeled wheat germ agglutinin-lectin (WGA) and 4',6-diamidino-2-phenylindole dihydrochloride (DAPI). The area of each cell was measured with a color image analyser and compared with its cytofluorometric nuclear DNA content. The endothelium in apparently intact regions of the diseased corneas showed the same DNA-ploidy pattern and cell area as the physiological corneas. However, endothelial cells in injured regions had greater area, even in diploidy, than in presumably normal ones and showed a larger number of hyperploid cells ranging from 4C to 36C. Hyperploid cells consisted of many multinucleates and few polyploidies and had extremely large and bizarre cytoplasm. All injured corneas were accompanied by cells with numerous micronuclei. A few asymmetrical 4C-binucleates (with DNA values such as 1.3 plus 2.6C) appeared in the case of the post-ICCE. It is concluded that damage to human corneal endothelial cells in vivo results in cell enlargement with or without DNA synthesis. Those changes appear more severe in diseased corneas than in the situation of physiological aging which we have reported previously. In severe cases, micronuclei, polyploid cells and multinucleated giant cells are frequent, thereby suggesting a possible long-persistent metabolic impairment of the endothelium after severe damage to the cornea.