RESUMEN
A comprehensive light and ultrastructural examination of the cornea in Domestic Pigs (Sus scrofa domesticus) revealed four distinct layers: the anterior epithelium, corneal stroma, Descemet's membrane and endothelium. Although Bowman's layer was not distinctly identified through histology, histochemical analysis indicated the presence of a rudimentary Bowman's layer, possibly vestigial from evolution. Scanning electron microscopy of the outer corneal surface unveiled two cell types, characterized by micro-projections, with light cells exhibiting shorter, thicker projections compared to dark cells. Examination of the inner surface via scanning electron microscopy demonstrated an endothelial layer devoid of cilia and microvilli, yet faint round to oval elevations were observed, potentially representing cell nuclei. Transmission electron microscopy unveiled that basal cells of the anterior epithelium closely adhered to the basement membrane, featuring half desmosomes along the basal surface. These basal cells extensively interconnected through interdigitations and a few desmosomes. The superficial cell layer consisted of a few rows of closely attached flat cells, forming a leak-proof layer with zona occludens. The outermost cells of this layer displayed fine projections to enhance the surface area, facilitating tear film distribution. At lower magnification, Transmission electron microscopy of the corneal stroma revealed alternating light and dark bands, with light bands representing transverse sections of collagen fibril lamellae and dark bands corresponding to longitudinal or oblique sections. Spindle-shaped keratocytes (fibroblasts) were identified as the primary stromal cells, intermingled between the lamellae, and featured long processes in close contact with neighbouring keratocytes. Overall, the histomorphology of the pig cornea resembles that of the human cornea except indistinct Bowman's membrane. This detailed understanding of the normal corneal structure in pigs hold great significance for biomedical research, providing a valuable reference for studies involving this animal model.
Asunto(s)
Córnea , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Sus scrofa , Animales , Córnea/ultraestructura , Córnea/anatomía & histología , Microscopía Electrónica de Transmisión/veterinaria , Microscopía Electrónica de Rastreo/veterinaria , Sus scrofa/anatomía & histología , Sustancia Propia/ultraestructura , Endotelio Corneal/ultraestructura , Endotelio Corneal/anatomía & histología , Epitelio Corneal/ultraestructura , Lámina Limitante Posterior/ultraestructura , Lámina Limitante Posterior/anatomía & histología , Porcinos/anatomía & histología , Lámina Limitante Anterior/ultraestructura , Lámina Limitante Anterior/anatomía & histologíaRESUMEN
PURPOSE: A morphological and morphometric study of the adult zebrafish ocular surface was performed to provide a comprehensive description of its parts and to evaluate its similarity to the human. MATERIALS AND METHODS: The eyes of adult zebrafish were processed for light, transmission and scanning electron microscopy, and for immunohistochemical stain of corneal nerves; a morphometric analysis was also performed on several morphological parameters. RESULTS: The corneal epithelium was formed by five layers of cells. No Bowman's layer could be demonstrated. The stroma consisted of lamellae of different thickness with few keratocytes. The Descemet's membrane was absent as the flat and polygonal endothelial cells directly adhered to the deepest corneal lamella. The immunohistochemical stain of neurofilaments failed to demonstrate corneal nerve fibers. The conjunctival epithelium was stratified, overlying the stroma formed by a subepithelial and a deep layer, this latter connected to the scleral cartilage. In the peripheral cornea and in the conjunctiva, many goblet and rodlet cells were observed. The morphometric analysis showed that the peripheral cornea epithelium was thicker when compared to the other parts of the ocular surface, with smaller superficial cells. Desmosomes and hemidesmosomes in the conjunctiva were significantly fewer in number than the other parts of the ocular surface. The stroma was thinner in the conjunctiva than in the cornea, while corneal lamellae were thicker in the intermediate stroma. CONCLUSIONS: The zebrafish ocular surface showed significant differences compared to the human, such as the absence of Bowman's layer, Descemet's membrane and corneal nerve fibers, the reduced stromal thickness, and the presence of rodlet cells. On the basis of these original findings, it is suggested that the use of the zebrafish as a model for studying normal or pathological human corneas should be undertaken with particular caution.
Asunto(s)
Córnea/anatomía & histología , Córnea/ultraestructura , Enfermedades de la Córnea , Modelos Animales , Pez Cebra/anatomía & histología , Animales , Lámina Limitante Anterior/ultraestructura , Conjuntiva/citología , Córnea/inervación , Sustancia Propia/citología , Lámina Limitante Posterior/ultraestructura , Endotelio Corneal/citología , Células Epiteliales/citología , Epitelio Corneal/citología , Células Caliciformes/citología , Humanos , Microscopía Electrónica de Rastreo , Microscopía Electrónica de Transmisión , Nervio Trigémino/anatomía & histologíaRESUMEN
PURPOSE: To evaluate the technical feasibility of isolated Bowman layer (BL) graft preparation by femtosecond laser (FSL) and to compare the ultrastructural morphology to manually dissected grafts. METHODS: Five whole globes were placed in custom-made eye holders and debrided of epithelium. After programming a dissection depth of 20 µm, the FSL was docked into position and 5 isolated BL grafts were created. From 5 additional globes, corneoscleral buttons were procured, mounted in artificial anterior chambers, and stripped of BL via the previously described manual technique. Three specimens from both series were randomly selected and assigned to transmission electron microscopy for ultrastructural evaluation and thickness measurements. RESULTS: All dissections were uneventful and 10 total grafts were produced: 5 by FSL and 5 by manual dissection. Mean graft thickness was 37 (±8.6) µm (n = 3) for the FSL group and 11.7 (±1.6) µm (n = 3) for the manually dissected group. Transmission electron microscopy revealed a thick but relatively smooth posterior cut edge in the FSL group, versus a virtually isolated BL with irregular rests of dispersed stroma in the manually dissected group. CONCLUSIONS: Femtosecond laser may have potential for harvesting intact BL and with a smooth posterior surface, but accompanied by variable amounts of anterior stroma owing to technical limitations.
Asunto(s)
Lámina Limitante Anterior/cirugía , Trasplante de Córnea/métodos , Queratocono/cirugía , Terapia por Láser/métodos , Donantes de Tejidos , Recolección de Tejidos y Órganos/métodos , Anciano , Lámina Limitante Anterior/ultraestructura , Estudios de Factibilidad , Femenino , Humanos , Masculino , Microscopía Electrónica de Transmisión , Proyectos Piloto , Reproducibilidad de los ResultadosRESUMEN
BACKGROUND: Reis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman's layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree. METHODS: Subjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry. RESULTS: Eight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman's layer was absent, replaced by abnormal deposits stain bright red with Masson's trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte. CONCLUSIONS: The study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.
Asunto(s)
Distrofias Hereditarias de la Córnea/genética , Distrofias Hereditarias de la Córnea/patología , Factor de Crecimiento Transformador beta/genética , Adolescente , Adulto , Anciano , Pueblo Asiatico , Lámina Limitante Anterior/patología , Lámina Limitante Anterior/ultraestructura , Niño , Preescolar , Córnea/patología , Córnea/ultraestructura , Distrofias Hereditarias de la Córnea/cirugía , Queratocitos de la Córnea/patología , Sustancia Propia/patología , Sustancia Propia/ultraestructura , Exones , Proteínas de la Matriz Extracelular/genética , Femenino , Humanos , Inmunohistoquímica , Queratoplastia Penetrante , Masculino , Microscopía Confocal , Microscopía Electrónica de Transmisión , Persona de Mediana Edad , Mutación , Linaje , Reacción en Cadena de la Polimerasa , Tomografía de Coherencia Óptica , Adulto JovenRESUMEN
PURPOSE: The purpose of this study was to identify ultrastructural changes associated with ectasia and to determine the association between lamellar count and corneal thinning. METHODS: Five surgically removed keratoconic corneal buttons and four, non-keratoconic, normal eye bank control corneas were processed for transmission electron microscopy using an established protocol, ensuring minimal tissue distortion. A sequence of overlapping digital images, spanning the full apical cone corneal thickness, was assembled. A seamless digital montage was printed at 5000× magnification. Lamellae were counted in the anterior-posterior orientation, along a linear line, using established criteria for identification of individual lamellae. RESULTS: The stromal thickness estimated as a 95% confidence interval for the mean, CI (0.95), in the keratoconic corneas was 372 ± 62 µm, while in the normal cornea, it was 446 ± 89 µm. All keratoconic corneas showed ultrastructural evidence of lamellar splitting and a loss of interweaving anterior lamellae. In the keratoconic corneas, the median total linear stromal lamellar absolute count tangential to the corneal surface was 362, (25th percentile; 75th percentile) = (355; 365) lamellae and in the normal cornea, 246, (25th percentile; 75th percentile) = (239; 251). The linear lamellar density in the keratoconic corneas was estimated as CI (0.95) 117 ± 22 and 86 ±19 lamellae per 100 µm in the anterior and posterior portion of the stroma, respectively. In normal cornea, the linear lamellar density was estimated as CI (0.95) 51 ± 8 and 80 ± 20 lamellae per 100 µm. The mean difference of linear lamellar count between the anterior and the posterior portion of the cornea was estimated as CI (0.95) 31 ± 23 for keratoconic corneas and -29 ± 28 for the normal corneas. CONCLUSIONS: The current morphometric analysis of ultrastructural changes suggests that ectasia and thinning in keratoconus is associated with lamellar splitting into multiple bundles of collagen fibrils and loss of anterior lamellae. These structural changes, possibly in addition to lateral shifting of lamellae due to the pressure gradient over the cornea, are a potential explanation to the central loss of mass.
Asunto(s)
Tejido Conectivo/ultraestructura , Sustancia Propia/ultraestructura , Queratocono/patología , Adulto , Anciano , Lámina Limitante Anterior/ultraestructura , Topografía de la Córnea , Dilatación Patológica/patología , Femenino , Humanos , Queratocono/cirugía , Queratoplastia Penetrante , Masculino , Microscopía Electrónica de Transmisión , Persona de Mediana EdadRESUMEN
The objective of this study is to further investigate the ultrastructural details of the surface of Bowman's membrane of the human cornea, using atomic force microscopy (AFM) images. One representative image acquired of Bowman's membrane of a human cornea was investigated. The three-dimensional (3-D) surface of the sample was imaged using AFM in contact mode, while the sample was completely submerged in optisol solution. Height and deflection images were acquired at multiple scan lengths using the MFP-3D AFM system software (Asylum Research, Santa Barbara, CA), based in IGOR Pro (WaveMetrics, Lake Oswego, OR). A novel approach, based on computational algorithms for fractal analysis of surfaces applied for AFM data, was utilized to analyze the surface structure. The surfaces revealed a fractal structure at the nanometer scale. The fractal dimension, D, provided quantitative values that characterize the scale properties of surface geometry. Detailed characterization of the surface topography was obtained using statistical parameters, in accordance with ISO 25178-2: 2012. Results obtained by fractal analysis confirm the relationship between the value of the fractal dimension and the statistical surface roughness parameters. The surface structure of Bowman's membrane of the human cornea is complex. The analyzed AFM images confirm a fractal nature of the surface, which is not taken into account by classical surface statistical parameters. Surface fractal dimension could be useful in ophthalmology to quantify corneal architectural changes associated with different disease states to further our understanding of disease evolution.
Asunto(s)
Lámina Limitante Anterior/ultraestructura , Fractales , Imagenología Tridimensional , Microscopía de Fuerza Atómica , HumanosRESUMEN
Our study performed qualitative and quantitative studies on the corneal ultrastructure of healthy female Merino sheep of ages 4 months and 6 years old from the Argentinean Pampa. The corneas were evaluated using ex vivo laser-scanning confocal microscopy, light microscopy and transmission electron microscopy. Those studies allowed us to obtain detailed images of the corneal layers as well as quantitative data of the cellular and sub-basal nerve densities in the cornea from sheep of different ages. The density of the corneal cells was significantly different in the anterior versus the posterior epithelium and stroma. Moreover, the density of the epithelial, stromal cells and endothelial cells, as well as the sub-basal nerve density were significantly lower in adult than in young animals. Our work provided a wide-ranging description of the corneal ultrastructure of healthy female Merino sheep, which adds to the current knowledge about the ophthalmological aspects of this species and undoubtedly benefits veterinarians.
Asunto(s)
Córnea/ultraestructura , Ovinos/anatomía & histología , Factores de Edad , Animales , Argentina , Lámina Limitante Anterior/ultraestructura , Córnea/inervación , Sustancia Propia/citología , Sustancia Propia/inervación , Sustancia Propia/ultraestructura , Lámina Limitante Posterior/citología , Lámina Limitante Posterior/ultraestructura , Células Endoteliales/ultraestructura , Endotelio Corneal/citología , Endotelio Corneal/ultraestructura , Epitelio Corneal/ultraestructura , Femenino , Procesamiento de Imagen Asistido por Computador , Microscopía Confocal/veterinaria , Microscopía Electrónica de Transmisión/veterinariaRESUMEN
A 47-year-old woman required penetrating keratoplasty in the right eye after developing delayed visually significant corneal scarring bilaterally after laser in situ keratomileusis (LASIK) in 1997 following epikeratoplasty in 1987. Spectral domain ocular coherence tomography of the left cornea showed a 100 µm lenticule with a LASIK flap posterior to the host Bowman layer at 250 µm. Histopathology and electron microscopy of the right corneal button showed a 120 µm lenticule with a LASIK flap within the lenticule at 100 µm. Clinically significant scarring was present within the LASIK flap interface, within the lenticule stroma, and within the area of the underlying host Bowman layer. There were keratocytes at the junction between the LASIK flap and lenticule stromal bed. Although epikeratoplasty is no longer practiced, post-epikeratoplasty patients may present for refractive surgical options and LASIK carries significant risks for corneal scarring in these individuals, especially when using flap-creating devices that may create thin LASIK flaps.
Asunto(s)
Cicatriz/patología , Enfermedades de la Córnea/patología , Epiqueratofaquia , Queratomileusis por Láser In Situ/efectos adversos , Miopía/cirugía , Trastornos de la Visión/patología , Lámina Limitante Anterior/ultraestructura , Cicatriz/etiología , Cicatriz/cirugía , Enfermedades de la Córnea/etiología , Enfermedades de la Córnea/cirugía , Queratocitos de la Córnea/patología , Paquimetría Corneal , Femenino , Humanos , Queratoplastia Penetrante , Láseres de Excímeros , Persona de Mediana Edad , Reoperación , Colgajos Quirúrgicos/patología , Tomografía de Coherencia Óptica , Trastornos de la Visión/etiología , Trastornos de la Visión/cirugía , Agudeza Visual/fisiologíaRESUMEN
PURPOSE: The stroma is the major part of the cornea, in which collagen fibrils and proteoglycans are distributed uniformly. We describe the ultrastructure of corneal layers, collagen fibrils (CF), and proteoglycans (PGs) in the tree shrew cornea. METHODS: Tree shrew corneas (5, 6, and 10 week old animals) and normal human corneas (24, 25, and 54 years old) were fixed in 2.5% glutaraldehyde containing cuprolinic blue in a sodium acetate buffer. The tissue was processed for electron microscopy. The 'iTEM Olympus Soft Imaging Solutions GmbH' program was used to measure the corneal layers, collagen fibril diameters and proteoglycan areas. RESULTS: The tree shrew cornea consists of 5 layers: the epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. The epithelium was composed of squamous cells, wing cells and basal cells. The Bowman's layer was 5.5±1.0 µm thick and very similar to a normal human Bowman's layer. The stroma was 258±7.00 µm thick and consisted of collagen fibril lamellae. The lamellae were interlaced with one another in the anterior stroma, but ran parallel to one another in the middle and posterior stroma. Collagen fibrils were decorated with proteoglycan filaments with an area size of 390 ±438 nm(2). The collagen fibril had a minimum diameter of 39±4.25 nm. The interfibrillar spacing was 52.91±6.07 nm. Within the collagen fibrils, very small electron-dense particles were present. CONCLUSIONS: The structure of the tree shrew cornea is very similar to that of the normal human cornea. As is the case with the human cornea, the tree shrew cornea had a Bowman's layer, lamellar interlacing in the anterior stroma and electron-dense particles within the collagen fibrils. The similarities of the tree shrew cornea with the human cornea suggest that it could be a good structural model to use when studying changes in collagen fibrils and proteoglycans in non-genetic corneal diseases, such as ectasia caused after LASIK (laser-assisted in situ keratomileusis).
Asunto(s)
Lámina Limitante Anterior/ultraestructura , Sustancia Propia/ultraestructura , Lámina Limitante Posterior/ultraestructura , Endotelio Corneal/ultraestructura , Adulto , Factores de Edad , Animales , Colágeno/ultraestructura , Enfermedades de la Córnea/patología , Dilatación Patológica/etiología , Dilatación Patológica/patología , Matriz Extracelular/ultraestructura , Humanos , Queratomileusis por Láser In Situ/efectos adversos , Microscopía Electrónica , Persona de Mediana Edad , Proteoglicanos/ultraestructura , MusarañasRESUMEN
PURPOSE: To investigate the ultrastructure of advanced Salzmann nodular degeneration (SND) and to correlate it to confocal in vivo findings. METHODS: The corneal degenerative nodules from four patients with SND were examined with confocal microscopy and then removed and processed for light microscopy (LM) and transmission electron microscopy (TEM). RESULTS: The confocal examination revealed elongated basal epithelial cells and activated keratocytes in the anterior stroma near the nodules. Occasional subbasal nerves and tortuous stromal nerve bundles were observed. With LM and TEM, five zones were described: one internodular and four pertaining the nodule, each characterized by peculiar aspects of the epithelium and stroma. As also confirmed by the morphometry, in the zones corresponding to the nodules, the epithelium was lower and with fewer cell layers than the peripheral zones. Over the nodules, the basement membrane was discontinuous or absent and the Bowman's layer, when present, had a granular-filamentous appearance. The nodular stroma was formed by many activated keratocytes and irregular lamellae. Subbasal nerves were always isolated and had degenerative changes in the center of the nodule. CONCLUSIONS: This work illustrates the confocal microscopic findings associated with LM and TEM observations in patients with advanced SND. Our data revealed milder changes of the epithelium together with more pronounced changes of the basement membrane and Bowman's layer, which are aspects of increased keratocyte activity and an altered nerve pattern. All of these structures seem to contribute to the characteristic corneal disorganization of SND.
Asunto(s)
Distrofias Hereditarias de la Córnea/patología , Epitelio Corneal/patología , Epitelio Corneal/ultraestructura , Adulto , Membrana Basal/patología , Membrana Basal/ultraestructura , Lámina Limitante Anterior/patología , Lámina Limitante Anterior/ultraestructura , Células Epiteliales/patología , Células Epiteliales/ultraestructura , Epitelio Corneal/inervación , Femenino , Humanos , Masculino , Microscopía Confocal , Microscopía Electrónica de Transmisión , Persona de Mediana Edad , Fibras Nerviosas/patología , Fibras Nerviosas/ultraestructuraRESUMEN
AIMS: Keratan sulphate (KS) is the predominant glycosaminoglycan (GAG) present in the corneal stroma where it is thought to regulate collagen fibril diameter. In this study we investigated the distribution of KS in normal and keratoconic corneas. METHODS: Four normal, one mild, and four severe keratoconic corneas were used for the study. Distribution of keratan sulphate proteoglycans (KS-PG) was investigated using a primary monoclonal antibody (5-D-4) that recognizes disulphated disaccharides in the poly-N-acetyllactosamine repeats of KS. The immuno-reactivity of 5-D-4 was analyzed by immunohistochemistry and immuno-electron microscopy. RESULTS: Immuno-histochemistry showed diffuse 5-D-4 staining in keratoconic cornea compared to the punctuate staining in normal corneas. In the single cornea with mild keratoconus, immunogold microscopy revealed a very high density of KS-PG staining, especially in the posterior stroma, compared to severe keratoconic and normal cornea. The amount of KS-PG in the stroma in severe keratoconus was slightly less compared to the normal cornea. In the mild keratoconic cornea, a higher quantity of KS-PG was present around the keratocytes. In severe keratoconic corneas, a higher quantity of KS-PG was present within the keratocytes compared to normal cornea. CONCLUSIONS: The finding of an altered expression of KS in our keratoconic corneas, in particular the strong expression of KS in keratocytes, is in keeping with reports of an altered expression of proteoglycan metabolism in keratoconus. KS-PG plays an important role in stromal collagen fibril assembly and a dysregulation of KS-PG synthesis or catabolism could explain changes in collagen fibril spacing and diameter, which we have reported elsewhere.
Asunto(s)
Córnea/metabolismo , Sulfato de Queratano/metabolismo , Queratocono/metabolismo , Polisacáridos/metabolismo , Adulto , Anciano , Anticuerpos Monoclonales , Lámina Limitante Anterior/metabolismo , Lámina Limitante Anterior/ultraestructura , Membrana Celular/metabolismo , Membrana Celular/ultraestructura , Córnea/ultraestructura , Sustancia Propia/metabolismo , Sustancia Propia/ultraestructura , Lámina Limitante Posterior/metabolismo , Lámina Limitante Posterior/ultraestructura , Epitelio Corneal/metabolismo , Epitelio Corneal/ultraestructura , Técnica del Anticuerpo Fluorescente Indirecta , Humanos , Sulfato de Queratano/ultraestructura , Queratocono/patología , Microscopía Fluorescente , Microscopía Inmunoelectrónica , Persona de Mediana Edad , Polisacáridos/inmunología , Polisacáridos/ultraestructura , Sulfatos , Adulto JovenRESUMEN
Caffeine is one of the most frequently consumed psychoactive substances. It has been known for many years that caffeine at high concentrations exerts harmful effects on both women's and laboratory animals' fertility, moreover it may impair normal development of many organs in the prenatal period. So far there have been few studies performed that demonstrate teratogenic effects of caffeine on structures of the developing eye, particularly the cornea. The aim of the study was to show ultrastructural changes in the developing cornea, as the effect of caffeine administration to chicken embryos. The experimental materials were 26 chicken embryos from incubated breeding eggs. Eggs were divided into two groups: control (n=30) in which Ringer liquid was administrated, and experimental (n=30) in which teratogenic dose of caffeine 3.5mg/egg was given. In 36th hour of incubation solutions were given with cannula through hole in an egg shell directly onto amniotic membrane. After closing the hole with a glass plate and paraffine, eggs were put back to incubator. In 10th and 19th day of incubation corneas were taken for morphological analysis with a use of electron microscopy. Administration of caffeine during chicken development causes changes of collagen fibers of Bowman's membrane patterns and of the corneal stroma but it also changes proportion of amount of collagen fibers and of the stromal cells.
Asunto(s)
Cafeína/farmacología , Córnea/embriología , Teratógenos/farmacología , Animales , Lámina Limitante Anterior/efectos de los fármacos , Lámina Limitante Anterior/metabolismo , Lámina Limitante Anterior/ultraestructura , Calcio/farmacología , Catéteres , Embrión de Pollo , Colágeno/metabolismo , Colágeno/ultraestructura , Córnea/efectos de los fármacos , Córnea/ultraestructura , Sustancia Propia/citología , Sustancia Propia/efectos de los fármacos , Sustancia Propia/ultraestructura , Relación Dosis-Respuesta a Droga , Huevos , Microscopía , Microscopía Electrónica , Distribución Aleatoria , Factores de TiempoRESUMEN
PURPOSE: To investigate the cut quality and surface characteristics of the epithelial flap and underlying Bowman's membrane created by the Amadeus II (AMO) microkeratome on human corneas using light and electron microscopy. SETTING: Center for Refractive Therapy, Department of Ophthalmology, Ludwig-Maximilians University, Munich, Germany. METHODS: Using a 9.0 mm type II suction ring and settings, as recommended by the manufacturer, epithelial laser in situ keratomileusis (epi-LASIK) was performed in 2 fresh human eyes of 1 donor. Ocular pathology and previous ocular surgery were ruled out. Tissues for light microscopy were examined using hematoxylin-eosin and periodic acid-Schiff reaction staining. Further tissue samples were examined using scanning electron microscopy and transmission electron microscopy. RESULTS: Light microscopy showed a thoroughly separated epithelial sheet with no evident anatomical abnormalities. Stratification of the separated epithelium layer and cell shape was conserved. The cleavage plane was located at Bowman's membrane. Scanning electron microscopy showed a consistent transition from adherent epithelium to the denuded area. Bowman's layer showed a very smooth surface without remains of basal lamina. Transmission electron microscopy examination showed interruptions of the basement membrane at high magnification. CONCLUSIONS: This in vitro study found a high cut quality using the epi-LASIK separator of the Amadeus II microkeratome. The resulting cleavage plane at Bowman's membrane was well suited for the subsequent laser ablation.
Asunto(s)
Lámina Limitante Anterior/ultraestructura , Epitelio Corneal/cirugía , Epitelio Corneal/ultraestructura , Queratomileusis por Láser In Situ/normas , Colgajos Quirúrgicos/patología , Lámina Limitante Anterior/cirugía , Humanos , Queratomileusis por Láser In Situ/instrumentación , Microscopía Electrónica de Rastreo , Donantes de TejidosRESUMEN
PURPOSE: To explore the histopathologic and ultrastructure changes of corneal dystrophies of bowman layer, type I (CDB I ) in Chinese. METHODS: Cornea buttons were obtained from 4 CDB I patients in 2 pedigrees who underwent lamella or penetrating keratoplasty. Sections with HE and special staining were observed under light microscope. Ultrathin sections were performed and ultrastructure changes were investigated under transmission electron microscope. Two normal cornea specimens were used as control. RESULTS: In the CDB I cornea epithelium, microvillus were decreased or lost. Small clumps of deposits with high electron density were found between basal cells. Some basal cells appeared apoptosis sign. A great quantity of rod-shape deposits were seen in Bowman's layer and the anterior part of stroma. CONCLUSIONS: CDB I patients have characteristic corneal structure changes, and may be one of the reasons of the clinical symptoms.