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Ramsey, David T., Joe G. Hauptman y Simon M. Petersen-Jones. "Corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa or clinically normal corneas". American Journal of Veterinary Research 60, n.º 10 (1 de octubre de 1999): 1317. http://dx.doi.org/10.2460/ajvr.1999.60.10.1317.
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Abstract Objective To compare corneal thickness, intraocular pressure, and optical corneal diameter in Rocky Mountain Horses with cornea globosa and those with clinically normal corneas. Animals 129 Rocky Mountain Horses. Procedure Ultrasonic pachymetry was used to measure corneal thickness. Applanation tonometry was used to measure intraocular pressure. A Jameson caliper was used to measure optical corneal diameter. Results The central and temporal peripheral portions of the cornea were significantly thicker in horses with cornea globosa than in horses with clinically normal corneas, but corneal thicknesses in the dorsal, ventral, and medial peripheral portions of the cornea were not significantly different between groups. There were no differences in corneal thickness between male and female horses or between right and left eyes. However, there was a positive correlation between age and corneal thickness. Intraocular pressure was not significantly different between horses with cornea globosa and those with clinically normal corneas, or between right and left eyes, or male and female horses. Optical corneal diameter for horses with cornea globosa was not significantly different from diameter for horses with clinically normal corneas, but optical corneal diameter was positively correlated with age. Conclusions and Clinical Relevance Cornea globosa in Rocky Mountain Horses is not associated with increased intraocular pressure. Corneal thickness and optical corneal diameter increase with age in Rocky Mountain Horses. (Am J Vet Res 1999;60:1317–1321)
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Liang, Wentao, Li Huang, Xiang Ma, Lijie Dong, Rui Cheng, Marcus Dehdarani, Dimitrios Karamichos y Jian-xing Ma. "Pathogenic Role of Diabetes-Induced Overexpression of Kallistatin in Corneal Wound Healing Deficiency Through Inhibition of Canonical Wnt Signaling". Diabetes 71, n.º 4 (19 de enero de 2022): 747–61. http://dx.doi.org/10.2337/db21-0740.
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It was reported previously that circulation levels of kallistatin, an endogenous Wnt signaling inhibitor, are increased in patients with diabetes. The current study was conducted to determine the role of kallistatin in delayed wound healing in diabetic corneas. Immunostaining and Western blot analysis showed kallistatin levels were upregulated in corneas from humans and rodents with diabetes. In murine corneal wound healing models, the canonical Wnt signaling was activated in nondiabetic corneas and suppressed in diabetic corneas, correlating with delayed wound healing. Transgenic expression of kallistatin suppressed the activation of Wnt signaling in the cornea and delayed wound healing. Local inhibition of Wnt signaling in the cornea by kallistatin, an LRP6-blocking antibody, or the soluble VLDL receptor ectodomain (an endogenous Wnt signaling inhibitor) delayed wound healing. In contrast, ablation of the VLDL receptor resulted in overactivation of Wnt/β-catenin signaling and accelerated corneal wound healing. Activation of Wnt signaling in the cornea accelerated wound healing. Activation of Wnt signaling promoted human corneal epithelial cell migration and proliferation, which was attenuated by kallistatin. Our findings suggested that diabetes-induced overexpression of kallistatin contributes to delayed corneal wound healing by inhibiting the canonical Wnt signaling. Thus, kallistatin and Wnt/β-catenin signaling in the cornea could be potential therapeutic targets for diabetic corneal complications.
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Daxer, Albert. "Biomechanics of the Cornea". International Journal of Keratoconus and Ectatic Corneal Diseases 3, n.º 2 (2014): 57–62. http://dx.doi.org/10.5005/jp-journals-10025-1080.
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ABSTRACT The purpose of this article is to provide an applicable and easy-to-use mathematical model of the biomechanics of the cornea. The new spherical dome model considers not only the heterogeneity of the tunica of the eye and distinguishes structurally between cornea, limbus and sclera. It also implements the structural anisotropy inside the corneal stroma caused by the corneas lamellar structure as well as the asphericity of the corneal shape. How to cite this article Daxer A. Biomechanics of the Cornea. Int J Kerat Ect Cor Dis 2014;3(2):57-62.
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Ambrósio Jr., Renato, Louise Pellegrino G. Esporcatte, Karolyna Andrade de Carvalho, Marcella Q. Salomão, Amanda Luiza Pereira-Souza, Bernardo T. Lopes, Aydano P. Machado y Sebastian Marschall. "Combined Rotating Ultra-High-Resolution Spectral Domain OCT and Scheimpflug Imaging for In Vivo Corneal Optical Biopsy". Diagnostics 14, n.º 13 (8 de julio de 2024): 1455. http://dx.doi.org/10.3390/diagnostics14131455.
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Purpose: This article introduces the Pentacam® Cornea OCT (optical coherence tomography). This advanced corneal imaging system combines rotating ultra-high-resolution spectral domain OCT with sub- 2-micron axial resolution and Scheimpflug photography. The purpose of this study is to present the first experience with the instrument and its potential for corneal diagnostics, including optical biopsy. Methods: In this prospective study, the Pentacam® Cornea OCT was used to image the corneas of seven patients. The novel wide-angle pericentric scan system enables optimal OCT imaging performance for the corneal layer structure over the entire width of the cornea, including the limbal regions. A detailed analysis of the resulting images assessed the synergism between the OCT and Scheimpflug photography. Results: The Pentacam® Cornea OCT demonstrated significantly improved image resolution and ability to individualize corneal layers with high quality. There is a synergism between the OCT high-definition signal to individualize details on the cornea and Scheimpflug photography to detect and quantify corneal scattering. The noncontact exam was proven safe, user-friendly, and effective for enabling optical biopsy. Conclusions: Pentacam® Cornea OCT is an advancement in corneal imaging technology. The ultra-high-resolution spectral domain OCT and Scheimpflug photography provide unprecedented detail and resolution, enabling optical biopsy and improving the understanding of corneal pathology. Further studies are necessary to compare and analyze the tomographic reconstructions of the cornea with the different wavelengths, which may provide helpful information for diagnosing and managing corneal diseases.
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Faganello, Cláudia Skilhan, Vanessa Ruiz Moura da Silva, Maria Cristina Caldart de Andrade, André Silva Carissimi y João Antonio Tadeu Pigatto. "Morphology of endothelial cells from different regions of the equine cornea". Ciência Rural 46, n.º 12 (15 de septiembre de 2016): 2223–28. http://dx.doi.org/10.1590/0103-8478cr20160216.
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ABSTRACT: The objective of this study was to evaluate the morphology of different regions of the equine cornea using optical microscopy. Both healthy eyes of eight horses, male or female, of different ages were evaluated. Corneas were stained with alizarin red vital dye and subsequently examined and photographed using optical microscopy. Corneal endothelial morphology of central, superior, inferior, temporal and nasal areas was assessed. One hundred endothelial cells from each corneal area were analyzed. The shape of the corneal endothelial cells of each corneal region was analyzed. Statistical data analysis was conducted using the Student's t test. Values of P<0.01 were considered significant. Regarding morphological analysis, no statistically significant differences were reported between the equine corneal regions analyzed. The present research suggested that there are no morphological differences between regions of the equine cornea. The values obtained in any region of the equine cornea can be extrapolated to other regions of the cornea and are representative of the cell morphology present in all regions of the cornea.
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Krasnov, M. S. y V. P. Yamskova. "The Effect of Bioregulators Isolated from Blood Serum and Cornea of the Bovin’s Eye on the Condition of Tissue and Cells of the Rabbit Corneas during Cultivation and Storage". Ophthalmology in Russia 18, n.º 3 (1 de octubre de 2021): 488–94. http://dx.doi.org/10.18008/1816-5095-2021-3-488-494.
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Objective: to study the condition of the cornea, as well as its epithelial and endothelial cells, while maintaining in vitro at various temperature conditions, under the influence of a number of factors, including bioregulators isolated from blood serum and cornea of the bovine, and epidermal growth factor.Methods. The study was carried out on rabbit corneas stored at temperatures of +4, –86 °C, as well as the cultivation of endothelial and epithelial cells isolated from the cornea after storage at these temperatures, followed by histological and immunohistochemical studies.Results. Storage of the cornea at +4 °C for 10 days leads to corneal edema and significantly reduces their transparency, both bioregulators partially prevent a decrease in the transparency of the cornea, while the endothelial layer lyses in groups with the addition of epidermal growth factor and corneal bioregulator; but remains in the cornea with the addition of a serum bioregulator. All three factors contribute to the preservation of the Bowman membrane. In the corneas stored at –86 °C on the 30th day, a preserved endothelial layer was observed, and the epithelium retained its multilayering in all groups with the addition of factors other than the control group. In the control samples, the epithelial layer partially exfoliated, the endothelial layer was almost completely lysed. Both bioregulators stimulated the proliferation of cells isolated from the native cornea and enhanced the action of the epidermal growth factor. Similar results were obtained on cells isolated from stored corneas for 2 weeks at –86 °C. In the case of combined use of the epidermal growth factor and bioregulators on the 30th day, the endothelial layer was mainly preserved, the Descemet’s membrane was not broken. In the control samples, the epithelium was mainly single-layered, partially exfoliated, and the endothelial layer was completely lysed.Conclusion. Storage of cornea during hypothermia (+4 °С) does not provide corneal viability for longer than 10 days. Storage under conditions of cryopreservation (–86 °C) ensures the viability of the cornea for 60 days. Adding bioregulators and an epidermal growth factor to the basic preservation medium allows one to obtain a structurally safe and viable cornea, while all cellular layers of the cornea, including the endothelial layer, are preserved and viable.
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Abou-Slaybi, Abdo, Arsia Jamali, Deshea L. Harris, Yashar Seyed-Razavi y Pedram Hamrah. "Analysis of leukocyte populations and nerves in developing murine corneas". Journal of Immunology 202, n.º 1_Supplement (1 de mayo de 2019): 117.15. http://dx.doi.org/10.4049/jimmunol.202.supp.117.15.
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Abstract The avascular cornea is the most densely innervated tissue in the body and is endowed with resident bone marrow-derived cells. We have identified a novel subset of resident corneal plasmacytoid dendritic cells (pDCs). We have shown pDCs support corneal nerves through release of nerve growth factor (NGF). This study was to examine the presence of pDCs in the developing cornea. We examined corneas from E17, P2, and 8 week adult C57BL/6 mice. Corneas were stained for the pan-leukocyte marker CD45, the pDC marker plasmacytoid dendritic cell antigen-1 (PDCA-1), the pan-neuronal marker bIII-tubulin. Corneal CD45+ and PDCA-1+ cells and nerves were quantified. Significance was assigned by ANOVA and post-hoc Tukey test. All data is reported as mean ± standard deviation. Corneal CD45+ leukocyte density increased from E17 (65.4±14 cells/mm2) to P2 pups (301.9±19 cells/mm2, p<0.05). Both E17 and P2 corneas had lower CD45+ density when compared to adults (345±34 cells/mm2, p<0.05). We observed pDCs in the anterior stroma proximal to corneal nerves in E17, P2, and adult corneas. In E17, few pDCs were present in the peripheral cornea (1.5±2.6 cells/mm2), with none in the central cornea. In P2, pDCs were found in the periphery (68.19±8.99 cells/mm2), but not central corneas. The density of pDCs in adult peripheral (82.2±5.1 cells/mm2) and central (51.6±4.9 cells/mm2) corneas was greater than E17 (p<0.001) and P2 (p<0.05) corneas. Nerve density increased from E17 (45.43±6.75 mm/mm2) when compared to P2 (83.15±.21.6 mm/mm2 p<0.05) and to adult (151.6±3.25 mm/mm2 p<0.05) corneas. Our data show pDC density increased from embryonic, to neonatal, and adult corneas. Concurrently corneal nerve density increased during development from embryonic to adult mice.
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Monostori, Tamás, Diána Szűcs, Borbála Lovászi, Lajos Kemény y Zoltán Veréb. "Advances in tissue engineering and 3D bioprinting for corneal regeneration". International Journal of Bioprinting 10, n.º 1 (16 de enero de 2024): 1669. http://dx.doi.org/10.36922/ijb.1669.
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Blindness resulting from corneal damage affects millions of people worldwide. The scarcity of corneal donors adds a layer of complexity to patient treatment. Consequently, exploring artificial cornea substitutes has become imperative in the realm of clinical research. Scientific advancements have ushered in a plethora of innovative solutions, including keratoprostheses or decellularized cornea scaffolds. The development of three-dimensional (3D) printing has further expanded the horizons of research in this field, delving into the feasibility of bioprinted corneas and yielding numerous promising outcomes. However, the manufacturing of corneal products via 3D printing poses a substantial challenge, demanding a meticulous selection of materials and techniques to ensure the transparency and preservation of the optical and mechanical properties of the artificial cornea. In the review, we present the artificial cornea substitutes. Additionally, we aim to provide a concise overview of the 3D printing techniques and materials applicable to corneal bioprinting.
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Gilger, Brian C., R. David Whitley, Susan A. McLaughlin, James C. Wright y J. Wanzer Drane. "Canine corneal thickness measured by ultrasonic pachymetry". American Journal of Veterinary Research 52, n.º 10 (1 de octubre de 1991): 1570–72. http://dx.doi.org/10.2460/ajvr.1991.52.10.1570.
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SUMMARY Ultrasonic pachymetry was used to measure central, superior peripheral, and temporal peripheral corneal thicknesses of 75 dogs (150 eyes) with normal corneas, anterior chambers, and intraocular pressure. Mean corneal thickness averaged over the 2 eyes, 3 locations, and 75 dogs was 562 ± 6.2 μm. The peripheral cornea was thicker on average than the central cornea by 49.43 ± 8.45 μm and this difference increased with age at 6.97 ± 1.3 μm/month of age. Mean corneal thickness changed with age (14.23 ± 2.26 μm/month), and weight (1.83 ± 0.38 μm/kg). Females had significantly thinner corneas (22.43 ± 11.03 μm than males) after adjusting for age and weight.
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Romano, Vito, Zhuola Zhuola, Zhuo Chang, Bernhard Steger, Hannah J. Levis, Stephen B. Kaye y Riaz Akhtar. "Biomechanical evaluation of central and peripheral Descemet’s membrane endothelial graft". Modeling and Artificial Intelligence in Ophthalmology 2, n.º 2 (18 de junio de 2018): 47–51. http://dx.doi.org/10.35119/maio.v2i2.71.
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Corneal endothelial transplant is the gold-standard treatment in cases of corneal endothelial cellular dysfunction. Preparation, delivery, and unfolding of the graft are technically demanding. We assessed the biomechanical behavior of Descemet’s membrane to better understand Descemet’s membrane endothelial keratoplasty(DMEK) graft behavior, and to select the right diameter and donor age graft . The biomechanical behavior was tested using atomic force microscopy (AFM) on five corneas unsuitable for transplantation. The peripheral cornea was found to be stiffer than the central cornea (3171.89 MPa and 2837.20 MPa, respectively). The elastic modulus of both the central and peripheral cornea exhibited a trend to decrease with age. In addition, the central cornea becomes stiff er than the peripheral cornea in older patients, while the peripheral cornea was stiff er in younger patients. AFM is a suitable technique for evaluating biomechanical behavior of DMEK graft s. One interpretation of this varied behavior is that the type and quantity of collagen changes with age and location.
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Morishige, Naoyuki, James V. Jester, Julie Naito, Nelson Osorio, Andrew Wahlert, Clinton Jones, Roger D. Everett, Steven L. Wechsler y Guey Chuen Perng. "Herpes simplex virus type 1 ICP0 localizes in the stromal layer of infected rabbit corneas and resides predominantly in the cytoplasm and/or perinuclear region of rabbit keratocytes". Journal of General Virology 87, n.º 10 (1 de octubre de 2006): 2817–25. http://dx.doi.org/10.1099/vir.0.82076-0.
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Herpes stromal keratitis (HSK) results from the reactivation of herpes simplex virus type-1 (HSV-1) in the cornea. The subsequent corneal inflammation and neovascularization may lead to scarring and visual loss. The cellular and molecular mechanisms underlying HSK remain unknown. The presence of stromal HSV-1 viral proteins or antigens in the HSK cornea remains a subject of debate. It was recently reported that HSV-1 ICP0 rapidly diffuses out of infected rabbit corneas. To investigate further the presence of HSV-1 ICP0 in the infected cornea, particularly in the corneal stroma, ex vivo confocal microscopy was used to scan rabbit corneas infected with the virus ICP0–EYFP, an HSV-1 derivative (strain 17+) that expresses ICP0 fused to the enhanced yellow fluorescent protein (EYFP). These results demonstrate that ICP0 is expressed in the corneal epithelium and stromal cells (keratocytes) of infected rabbit corneas throughout acute infection. Furthermore, expression of ICP0–EYFP appears localized to punctate, granular deposits within stromal keratocytes, showing both a cytoplasmic and perinuclear localization. These findings provide new data demonstrating that anterior corneal keratocytes become infected and express ICP0 during acute HSV-1 infection.
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Liu, Zichen, Chang Yu, Yiwen Song, Mo Pang y Yipeng Jin. "The Clinical Guiding Role of the Distribution of Corneal Nerves in the Selection of Incision for Penetrating Corneal Surgery in Canines". Veterinary Sciences 8, n.º 12 (8 de diciembre de 2021): 313. http://dx.doi.org/10.3390/vetsci8120313.
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The cornea is one of the regions with the highest density of nerve terminals in the animal body and it bears such functions as nourishing the cornea and maintaining corneal sensation. In veterinary clinical practice, the corneoscleral limbus incision is frequently applied in cataract surgery, peripheral iridectomy, and other procedures for glaucoma. Inevitably, it would cause damage to the nerve roots that enter the cornea from the corneal limbus, thus inducing a series of complications. In this paper, the in vitro cornea (39 corneas from 23 canines, with ages ranging from 8 months old to 3 years old, including 12 male canines and 11 female canines) was divided into 6 zones, and the whole cornea was stained with gold chloride. After staining, corneal nerves formed neural networks at different levels of cornea. There was no significant difference in the number of nerve roots at the corneoscleral limbus between different zones (F = 1.983, p = 0.082), and the nerve roots at the corneoscleral limbus (mean value, 24.43; 95% CI, 23.43–25.42) were evenly distributed. Additionally, there was no significant difference in the number of corneal nerve roots between male and female canines (p = 0.143). There was also no significant difference in the number of corneal nerve roots between adult canines and puppies (p = 0.324). The results of the above analysis will provide a reasonable anatomical basis for selecting the incision location and orientation of penetrating surgery for the canine cornea in veterinary practice.
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Salazar-Villatoro, Lizbeth, Bibiana Chávez-Munguía, Celia Esther Guevara-Estrada, Anel Lagunes-Guillén, Dolores Hernández-Martínez, Ismael Castelan-Ramírez y Maritza Omaña-Molina. "Taurine, a Component of the Tear Film, Exacerbates the Pathogenic Mechanisms of Acanthamoeba castellanii in the Ex Vivo Amoebic Keratitis Model". Pathogens 12, n.º 8 (16 de agosto de 2023): 1049. http://dx.doi.org/10.3390/pathogens12081049.
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Acanthamoeba spp. is the etiological agent of amoebic keratitis. In this study, the effect of taurine in physiological concentrations in tears (195 μM) on trophozoites of Acanthamoeba castellanii through the ex vivo amoebic keratitis model was evaluated. Trophozoites were coincubated with the Syrian golden hamster cornea (Mesocricetus auratus) for 3 and 6 h. Group 1: Control (−). Corneas coincubated with amoebic culture medium and taurine. Group 2: Control (+). Corneas coincubated with trophozoites without taurine. Group 3: Corneas coincubated with taurine 15 min before adding trophozoites. Group 4: Trophozoites coincubated 15 min with taurine before placing them on the cornea. Group 5: Corneas coincubated for 15 min with trophozoites; subsequently, taurine was added. Results are similar for both times, as evaluated by scanning electron microscopy. As expected, in the corneas of Group 1, no alterations were observed in the corneal epithelium. In the corneas of Group 2, few adhered trophozoites were observed on the corneal surface initiating migrations through cell junctions as previously described; however, in corneas of Groups 3, 4 and 5, abundant trophozoites were observed, penetrating through different corneal cell areas, emitting food cups and destabilizing corneal surface in areas far from cell junctions. Significant differences were confirmed in trophozoites adherence coincubated with taurine (p < 0.05). Taurine does not prevent the adhesion and invasion of the amoebae, nor does it favor its detachment once these have adhered to the cornea, suggesting that taurine in the physiological concentrations found in tears stimulates pathogenic mechanisms of A. castellanii.
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Akhtar, Saeed, Hind M. Alkatan, Omar Kirat, Adnan A. Khan y Turki Almubrad. "Collagen Fibrils and Proteoglycans of Macular Dystrophy Cornea: Ultrastructure and 3D Transmission Electron Tomography". Microscopy and Microanalysis 21, n.º 3 (5 de mayo de 2015): 666–79. http://dx.doi.org/10.1017/s1431927615000483.
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AbstractWe report the ultrastructure and 3D transmission electron tomography of collagen fibrils (CFs), proteoglycans (PGs), and microfibrils within the CF of corneas of patients with macular corneal dystrophy (MCD). Three normal corneas and three MCD corneas from three Saudi patients (aged 25, 31, and 49 years, respectively) were used for this study. The corneas were processed for light and electron microscopy studies. 3D images were composed from a set of 120 ultrastructural images using the program “Composer” and visualized using the program “Visuliser Kai”. 3D image analysis of MCD cornea showed a clear organization of PGs around the CF at very high magnification and degeneration of the microfibrils within the CF. Within the MCD cornea, the PG area in the anterior stroma was significantly larger than in the middle and posterior stroma. The PG area in the MCD cornea was significantly larger compared with the PG area in the normal cornea. The CF diameter and inter-fibrillar spacing of the MCD cornea were significantly smaller compared with those of the normal cornea. Ultrastructural 3D imaging showed that the production of unsulfated keratin sulfate (KS) may lead to the degeneration of micro-CFs within the CFs. The effect of the unsulfated KS was higher in the anterior stroma compared with the posterior stroma.
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Wu, Chun-Yen, Da-Fong Song, Zhi-Jia Chen, Chao-Sheng Hu, David Pei-Cheng Lin y Han-Hsin Chang. "Absence of the Klotho Function Causes Cornea Degeneration with Specific Features Resembling Fuchs Endothelial Corneal Dystrophy and Bullous Keratopathy". Biology 13, n.º 3 (20 de febrero de 2024): 133. http://dx.doi.org/10.3390/biology13030133.
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The Klotho loss-of-function mutation is known to cause accelerated senescence in many organs, but its effects on the cornea have not been published. The present study aims to investigate the effects of the Klotho null mutation on cornea degeneration and to characterize the pathological features. Mouse corneas of Klotho homozygous, heterozygous, and wild-type mice at 8 weeks of age for both genders were subject to pathological and immunohistological examinations. The results show an irregular topography on the corneal surface with a Klotho null mutation. Histological examinations revealed a reduced corneal epithelial cell density, endothelial cell-shedding, and decreased cornea stromal layer thickness in the absence of the Klotho function. Furthermore, guttae formation and the desquamation of wing cells were significantly increased, which was comparable to the characteristics of Fuchs endothelial corneal dystrophy and bullous keratopathy. The mechanism analysis showed multi-fold abnormalities, including oxidative stress-induced cornea epithelium apoptosis and inflammation, extracellular matrix remodeling in the stroma, and a disruption of epithelial repair, presumably through the epithelial–mesenchymal transition. In conclusion, cornea degeneration was observed in the Klotho loss-of-function mutant mice. These pathological features support the use of Klotho mutant mice for investigating age-related cornea anomalies, including Fuchs endothelial corneal dystrophy, bullous keratopathy, and dry eye diseases.
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Anisimov, S. I., N. S. Anisimova, I. A. Popov, A. G. Shilkin y M. N. Orlova. "The study of ability to integrate with the recipient cornea of xenomaterial “Corneoplast” for keratoplasty in the animal experiment". EYE GLAZ 25, n.º 1 (1 de abril de 2023): 49–55. http://dx.doi.org/10.33791/2222-4408-2023-1-49-55.
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Currently, there is a significant shortage of donor materials for replacing corneal tissue that is why it is relevant to create xenomaterials, which are able to replace a donor cornea with various types of keratoplasty. “Corneoplast” is a new medical device, which is a devitalized, fixed by the method of double crosslinking (dehydrothermic + UV), pork cornea.Purpose: to assess the biocompatibility and ability to integrate with the recipient cornea of implants based on the xenomaterial “Corneoplast”.Materials and methods. The experiment was based on biomicroscopy examination, high-resolution optical coherence tomography and histological examination of the experimental rabbits’ corneas (group I–IV: total of 8 eyes were examined), where keratoplasty was performed with the “Corneoplast” material.Results. High biocompatibility and ability to integrate with the recipient’s cornea were observed in all types of keratoplasty: penetrating, superficial lamellar and intralamellar keratoplasty. On the next day, the implant was transparent with slight swelling of the recipient’s corneal stroma. A week later, the slight swelling of implant was recorded without cornea edema. Its transparency decreased. The recipient’s cornea was reactive. A month later, the moderate neovascularization was noted towards the sutures. After 6 months, the recipient’s cornea was clear, transparent. The implant was translucent and neovascularization was absent. The entire surface of cornea and implant was epithelialized. On the series of optical coherent tomograms, a normal thickness of the epithelium continuous layer was determined in 6 months after the surgery. The complete integration of material with the recipient’s cornea was noted. The layered structure characteristic of corneal tissue was preserved. The cornea retained a layered structure and the endothelium was preserved. On histological examination, there were no differences in the intact cornea and implanted material.Conclusion. The “Corneoplast” material is sufficiently biocompatible and capable of integration with the recipient’s cornea in an animal experiment. This allows, at a certain stage of preclinical trials completion, to use it for replacing corneal tissue in penetrating keratoplasty, intralamellar and superficial anterior layer-by-layer implantations and to cover purulent corneal ulcers of various depths.
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Han, Xiao, Yubao Zhang, Yirui Zhu, Yanzhi Zhao, Hongwei Yang, Guo Liu, Sizhu Ai et al. "Quantification of biomechanical properties of human corneal scar using acoustic radiation force optical coherence elastography". Experimental Biology and Medicine 247, n.º 6 (3 de diciembre de 2021): 462–69. http://dx.doi.org/10.1177/15353702211061881.
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Biomechanical properties of corneal scar are strongly correlated with many corneal diseases and some types of corneal surgery, however, there is no elasticity information available about corneal scar to date. Here, we proposed an acoustic radiation force optical coherence elastography system to evaluate corneal scar elasticity. Elasticity quantification was first conducted on ex vivo rabbit corneas, and the results validate the efficacy of our system. Then, experiments were performed on an ex vivo human scarred cornea, where the structural features, the elastic wave propagations, and the corresponding Young’s modulus of both the scarred region and the normal region were achieved and based on this, 2D spatial distribution of Young’s modulus of the scarred cornea was depicted. Up to our knowledge, we realized the first elasticity quantification of corneal scar, which may provide a potent tool to promote clinical research on the disorders and surgery of the cornea.
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Hendricks, R. L., M. Janowicz y T. M. Tumpey. "Critical role of corneal Langerhans cells in the CD4- but not CD8-mediated immunopathology in herpes simplex virus-1-infected mouse corneas." Journal of Immunology 148, n.º 8 (15 de abril de 1992): 2522–29. http://dx.doi.org/10.4049/jimmunol.148.8.2522.
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Abstract Previous studies have revealed that the RE strain of HSV type 1 (HSV-1) induces a tissue-destructive inflammatory response in the mouse cornea that is mediated by CD4 T lymphocytes, whereas the KOS strain of HSV-1 preferentially activates CD8 T lymphocytes in the cornea. Langerhans cells (LC) normally reside only at the periphery of the cornea but can migrate centripetally after HSV-1 infection. We studied the relative contribution of LC to the corneal inflammation induced by the KOS and RE strains of HSV-1. Ten days after infection, the central one-third of RE HSV-1-infected corneas contained an average of 5.7 LC/high-power field compared with 0.6 LC/high-power field in KOS-infected corneas. We hypothesized that the increased density of LC in RE HSV-1-infected corneas at the time of T lymphocyte infiltration contributed to the preferential activation of CD4 T lymphocytes in these corneas. To test this hypothesis, we gave mice a low dose of UV-B corneal irradiation (150 mJ/cm2) 1 day before infection with HSV-1. UV-B irradiation effectively prevented the migration of LC into the central cornea when measured 10 or 21 days after corneal infection with either HSV-1 strain. UV-B corneal irradiation had no effect on the CTL response to HSV-1 Ag in the regional lymph nodes after corneal infection with KOS or RE HSV-1. The delayed-type hypersensitivity response induced by both strains of virus, when measured 8 and 14 days after corneal infection, was significantly reduced by UV-B irradiation. UV-B irradiation significantly reduced the incidence (p = 0.0023) and severity (p = 0.0008) of corneal stromal disease induced by RE HSV-1 but did not significantly affect the stromal disease induced by KOS HSV-1. To distinguish between the effect of UV-B treatment on the afferent and efferent arms of the Ir in mice, we administered UV-B treatment to one eye, followed 24 h later by RE HSV-1 infection of both eyes. These mice developed a normal delayed-type hypersensitivity response, and stromal inflammation developed normally in the untreated eye. However, stromal inflammation was significantly reduced in the treated eye. Our findings suggest that LC play a critical role in the activation of HSV-reactive CD4 T lymphocytes in the cornea. Moreover, the type of corneal inflammation induced by different strains of HSV-1 may reflect their differential capacity to induce LC migration into the central cornea.
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Bae, So Hyeon y Youngsub Eom. "Physiological Changes in the Cornea When Wearing Rigid Gas Permeable Contact Lenses". Annals of Optometry and Contact Lens 23, n.º 1 (25 de marzo de 2024): 1–6. http://dx.doi.org/10.52725/aocl.2024.23.1.1.
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Rigid gas permeable (RGP) contact lenses are made of materials with excellent oxygen permeability and wettability, so they not only improve oxygen permeability compared to existing lenses, but also provide correction of refractive errors and improved vision in irregular corneas such as keratoconus. However, the hard material of the lens along with hypoxia and hypercapnia of the cornea caused by wearing RGP contact lenses cause various physiological changes in the cornea. Physiological changes in the cornea that may occur when wearing RGP contact lenses include mucin balls, decreased corneal epithelial thickness and increased size, decreased epithelial barrier function, corneal erosion and staining, decreased keratocyte density, decreased corneal sensitivity, and stromal opacities, contact lens‐induced peripheral ulcers, endothelial blebs, increased endothelial polymegethism, and changes in corneal shape. It is necessary to know the performance of the RGP contact lenses being prescribed, be aware of the physiological changes in the cornea caused by wearing RGP contact lenses, and provide the correct lens prescription along with appropriate education to the patient.
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Yang, Jiajin, Qiaomei Ren, Dong Zhao, Zhipeng Gao, Xiaona Li, Rui He y Weiyi Chen. "Corneal Adhesion Possesses the Characteristics of Solid and Membrane". Bioengineering 9, n.º 8 (16 de agosto de 2022): 394. http://dx.doi.org/10.3390/bioengineering9080394.
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Adhesion behavior usually occurs in corneas associated with clinical treatments. Physiologically, an intact natural cornea is inflated by intraocular pressure. Due to the inflation, the physiological cornea has a mechanical property likeness to membrane. This characteristic is ignored by the classical theory used to analyze the adhesion behavior of soft solids, such as the Johnson–Kendall–Roberts (JKR) model. Performing the pull-off test, this work evidenced that the classical JKR solution was suitable for computing the corneal adhesion force corresponding to the submillimeter scale of contact. However, when the cornea was contacted at a millimeter scale, the JKR solutions were clearly smaller than the related experimental data. The reason was correlated with the membranous characteristic of the natural cornea was not considered in the JKR solid model. In this work, the modified JKR model was superimposed by the contribution from the surface tension related to the corneal inflation due to the intraocular pressure. It should be treated as a solid when the cornea is contacted at a submillimeter scale, whereas for the contact at a larger size, the characteristic of the membrane should be considered in analyzing the corneal adhesion. The modified JKR model successfully described the adhesion characteristics of the cornea from solid to membrane.
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Silver, Frederick H., Tanmay Deshmukh, Dominick Benedetto y Michael Gonzalez-Mercedes. "Dynamic Ocular Response to Mechanical Loading: The Role of Viscoelasticity in Energy Dissipation by the Cornea". Biomimetics 8, n.º 1 (3 de febrero de 2023): 63. http://dx.doi.org/10.3390/biomimetics8010063.
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We have used vibrational optical coherence tomography (VOCT) to measure the resonant frequency, elastic modulus, and loss modulus of components of the anterior segment of pig eyes in vitro. Such basic biomechanical properties of the cornea have been shown to be abnormal not only in diseases of the anterior segment but also in posterior segment diseases as well. This information is needed to better understand corneal biomechanics in health and disease and to be able to diagnose the early stages of corneal pathologies. Results of dynamic viscoelastic studies on whole pig eyes and isolated corneas indicate that at low strain rates (30 Hz or less), the viscous loss modulus is as high as 0.6 times the elastic modulus for both whole eyes and corneas. This large viscous loss is similar to that of skin, which has been hypothesized to be dependent upon the physical association of proteoglycans with collagenous fibers. The energy dissipation properties of the cornea provide a mechanism to dissipate energy associated with blunt trauma, thereby preventing delamination and failure. The cornea possesses the ability to store impact energy and transmit excess energy to the posterior segment of the eye through its serial connection to the limbus and sclera. In this manner, the viscoelastic properties of the cornea, in concert with that of the posterior segment of the pig eye, function to prevent mechanical failure of the primary focusing element of the eye. Results of resonant frequency studies suggest that the 100–120 Hz and 150–160 Hz resonant frequency peaks reside in the anterior segment of the cornea since the removal of the anterior segment of the cornea decreases the peak heights at these resonant frequencies. These results suggest that there is more than one collagen fibril network found in the anterior portion of the cornea that provides structural integrity to prevent corneal delamination and that VOCT may be useful clinically to diagnose corneal diseases.
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Cejka, Cestmir, Jan Kossl, Barbora Hermankova, Vladimir Holan y Jitka Cejkova. "Molecular Hydrogen Effectively Heals Alkali-Injured Cornea via Suppression of Oxidative Stress". Oxidative Medicine and Cellular Longevity 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/8906027.
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The aim of this study was to examine the effect of molecular hydrogen (H2) on the healing of alkali-injured cornea. The effects of the solution of H2in phosphate buffered saline (PBS) or PBS alone topically applied on the alkali-injured rabbit cornea with 0.25 M NaOH were investigated using immunohistochemical and biochemical methods. Central corneal thickness taken as an index of corneal hydration was measured with an ultrasonic pachymeter. Results show that irrigation of the damaged eyes with H2solution immediately after the injury and then within next five days renewed corneal transparency lost after the injury and reduced corneal hydration increased after the injury to physiological levels within ten days after the injury. In contrast, in injured corneas treated with PBS, the transparency of damaged corneas remained lost and corneal hydration elevated. Later results—on day 20 after the injury—showed that in alkali-injured corneas treated with H2solution the expression of proinflammatory cytokines, peroxynitrite, detected by nitrotyrosine residues (NT), and malondialdehyde (MDA) expressions were very low or absent compared to PBS treated injured corneas, where NT and MDA expressions were present. In conclusion, H2solution favorably influenced corneal healing after alkali injury via suppression of oxidative stress.
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Bald, Matthew R., Christopher Stoeger, Joshua Galloway, Maolong Tang, Jeffrey Holiman y David Huang. "Use of Fourier-Domain Optical Coherence Tomography to Evaluate Anterior Stromal Opacities in Donor Corneas". Journal of Ophthalmology 2013 (2013): 1–5. http://dx.doi.org/10.1155/2013/397680.
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Purpose. To evaluate Fourier-domain optical coherence tomography (FD-OCT) as an adjunct to traditional slit lamp examination of donor corneas with suspected Anterior Stromal Opacities.Methods. Seven corneas suspected of having anterior stromal opacities by slit lamp examination were evaluated with FD-OCT. Each cornea was evaluated to confirm the presence of opacity and, if present, the depth of opacity was measured.Results. The opacity depth ranged from 82 μm to 624 μm. The initial slit lamp impressions of five of the seven corneas were confirmed by OCT. In two corneas, the OCT findings were different from the initial slit lamp impressions. Slit lamp examination of the first cornea gave the impression of anterior stromal scarring, but OCT showed that the opacity was limited to the epithelium. Slit lamp examination of the second cornea suggested opacity limited to the epithelium, but OCT identified significant sub-Bowman's scarring. In all cases, the Eye Bank Technicians reported that the location and depth of corneal opacity were more sharply defined by OCT than by slit lamp.Conclusion. The high resolution of OCT makes it easier to determine the location of corneal opacities compared to slit lamp examinations. This enhanced visualization can improve decisions regarding transplant suitability of donor corneas.
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Tang, Q., W. Chen y R. L. Hendricks. "Proinflammatory functions of IL-2 in herpes simplex virus corneal infection." Journal of Immunology 158, n.º 3 (1 de febrero de 1997): 1275–83. http://dx.doi.org/10.4049/jimmunol.158.3.1275.
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Abstract Herpes simplex virus type 1 infection of corneas can lead to blinding inflammation in the corneal stroma, which is referred to clinically as herpes stromal keratitis. In our mouse model of this prevalent human disease, a heavy polymorphonuclear neutrophil (PMN) infiltration of the infected cornea leads to progressive tissue destruction. This inflammatory process can be abrogated by in vivo depletion of CD4 T lymphocytes and by neutralization of the cytokines IL-2 and IFN-gamma. The goal of this study was to define the mechanisms by which IL-2 mediates the corneal inflammation. Systemic neutralization of IL-2 after the onset of corneal disease resulted in a rapid regression of inflammation and complete resolution in 50% of the treated mice. The disease remission was associated with loss of IFN-gamma expression in the cornea, as determined by immunohistochemistry, and a significant reduction of IFN-gamma mRNA, as measured by a semiquantitative reverse transcription-PCR analysis. Within 48 h after anti-IL-2 mAb administration, the PMN chemotactic gradient in the infected corneas was abolished, and those PMN that were already present in the central cornea exhibited clear signs of apoptotic cell death. Our results demonstrate that IL-2 mediates corneal inflammation by 1) regulating local IFN-gamma production in an autocrine or a paracrine fashion, 2) establishing a PMN chemotactic gradient, and 3) maintaining PMN viability in the cornea. These results suggest that IL-2 might be targeted for therapeutic intervention in this blinding disease.
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Rowe, Alexander, Stephen Harvey y Robert Hendricks. "IL-33/ST2 regulate innate IL-17 production and viral replication in the cornea following a herpes infection (MUC7P.760)". Journal of Immunology 192, n.º 1_Supplement (1 de mayo de 2014): 197.12. http://dx.doi.org/10.4049/jimmunol.192.supp.197.12.
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Abstract Poorly controlled infections and inflammation can both be very deleterious to tissues such as the cornea whose function requires clarity, so understanding the mechanisms controlling the balance between protective immunity and immunopathology is critical. Since the anti-inflammatory cytokine IL-33 and its receptor ST2 are constitutively expressed in the cornea, we investigated their role in regulating early stages of the immune response to herpes simplex virus type 1 (HSV-1) in the cornea. HSV-1 replicates in the corneal epithelium and is simultaneously axonally transported to the cornea innervating neuronal cell bodies in the trigeminal ganglion (TG). Compared to wild type controls, corneas of ST2 KO mice exhibited elevated IL-17 production from 4 hrs to at least 48 hrs after infection, which correlated with enhanced viral clearance from the cornea at 48 hrs (infectious virus in eye swabs, and viral genome copies in the cornea). Other anti-viral mediators such as IL-6 and type I interferons were not elevated in corneas of ST2 KO mice. Infected corneas of ST2 KO mice had increased numbers of neutrophils, but not macrophages or dendritic cells 2 days after infection. Surprisingly, viral titers in TG of infected ST2 KO mice were not significantly changed relative to wild type controls. We conclude that IL-33 selectively regulates an innate immune response to HSV-1 in the cornea at the expense of impaired viral clearance.
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Singh, Manmohan, Achuth Nair, Salavat R. Aglyamov y Kirill V. Larin. "Compressional Optical Coherence Elastography of the Cornea". Photonics 8, n.º 4 (7 de abril de 2021): 111. http://dx.doi.org/10.3390/photonics8040111.
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Assessing the biomechanical properties of the cornea is crucial for detecting the onset and progression of eye diseases. In this work, we demonstrate the application of compression-based optical coherence elastography (OCE) to measure the biomechanical properties of the cornea under various conditions, including validation in an in situ rabbit model and a demonstration of feasibility for in vivo measurements. Our results show a stark increase in the stiffness of the corneas as IOP was increased. Moreover, UV-A/riboflavin corneal collagen crosslinking (CXL) also dramatically increased the stiffness of the corneas. The results were consistent across 4 different scenarios (whole CXL in situ, partial CXL in situ, whole CXL in vivo, and partial CXL in vivo), emphasizing the reliability of compression OCE to measure corneal biomechanical properties and its potential for clinical applications.
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Singh, Sujaya, Reena Kaur, Marium Jamaluddin y Azida Juana. "ONE CORNEA TWO RECIPIENTS: FEEDING TWO BIRDS WITH ONE SCONE". Journal of Health and Translational Medicine 26, n.º 1 (10 de abril de 2023): 5–8. http://dx.doi.org/10.22452/jummec.vol26no1.2.
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The existing shortage of local donor corneas in our institution (University Malaya) and Malaysia, in general, prompted us to attempt the use of one donor cornea for two transplantation procedures; Descemet Stripping Endothelial Keratoplasty (DSEK) in a case of a pseudophakic bullous keratopathy (PBK) with underlying Fuchs endothelial dystrophy (FED) and lamellar patch graft in a case of limbal dermoid. The donor cornea was divided into anterior and posterior lamellae manually. The anterior corneal button was used as a patch graft for anterior lamellar keratoplasty in a 6-year-old patient with limbal dermoid, and the posterior corneal button was used for a DSEK procedure in a 68-year-old patient with corneal decompensation. Both patients had a stable and good visual outcome throughout a 1-year postoperative period. This allows the use of one corneal tissue by more than one recipient to overcome the shortage in donor corneas.
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Lee, Chaeyeon, Eun Jung Lee, Yoonkyung Jang, Jong Chul Han y Chang Won Kee. "Changes in Corneal Thickness in Congenital Glaucoma, Using Anterior Segment Optical Coherence Tomography". Journal of the Korean Ophthalmological Society 63, n.º 8 (15 de agosto de 2022): 692–99. http://dx.doi.org/10.3341/jkos.2022.63.8.692.
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Purpose: We examined corneal thickness, particularly morphological changes in the limbus, as the intraocular pressure increased in patients with congenital glaucoma.Methods: We retrospectively studied 31 children (47 eyes) with congenital glaucoma and 12 controls (12 eyes). We used anterior segment tomography to measure corneal thicknesses at the center, the midpoint of the 2-5 mm pericentral zone, the corneo-limbal junction, and the scleral spurs on the nasal and temporal sides. The peripheral central corneal thickness ratios were calculated and analyzed using a generalized estimation equation.Results: The cornea was significantly thinner in the glaucoma than in the control group. The difference was more prominent in the periphery than the center. Associated with such peripheral thinning, the corneal thickness ratios at the corneal-limbal junction and the center differed significantly between the two groups.Conclusions: In congenital glaucoma patients, the cornea is generally thinner than that of the controls, particularly at the corneo-limbal junction, suggesting that the limbus is biomechanically susceptible to deformation by intraocular pressure.
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Moiseeva, Irina y Alexander Stein. "Mathematical modelling of Maklakoff elastotonometry in the case of artificially created cornea inhomogeneity". Russian journal of biomechanics. 23, n.º 1 (29 de marzo de 2019): 5–16. http://dx.doi.org/10.15593/rjbiomech/2019.1.01.
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The mechanical response of the eye to cornea loading by wide flat stamps of different weights (Maklakoff elastotonometry) is studied in the case of artificially created strong inhomogeneity of the elastic properties of the cornea, which is formed due to vision correction surgery. The weakening of the cornea in the apical region or in the peripheral annular zone that lies a short distance from the sclera but is not adjacent to it is considered. The first case corresponds to correction of myopia and the second one to that of hyperopia. The cornea is modeled by a momentless, linearly elastic surface and the scleral region by an elastic reservoir that responds to changes in volume by changes in pressure. Within this representation, the mechanical properties of the cornea are characterized by the effective stiffness, a parameter that reflects both the elastic properties of the cornea material and the corneal thickness. It is shown that for moderate corneal stiffness the dependence of the tonometric pressure on the tonometer weight remains, similar to the case of homogeneous cornea, almost linear, which makes it possible to introduce the pressure difference coefficient as the slope of the corresponding straight line. The dependence of this coefficient on parameters that characterize the distribution of the elastic properties of the cornea is studied for various true pressures and scleral stiffnesses. The corneal inhomogeneity effect turned out to be qualitatively different for apical and peripheral weakening but insignificant. In the latter case, the effect is less expressed and, moreover, practically indiscernible. Thus, for operated eyes with moderately stiff corneas, the earlier developed methods of clinical estimation of elastotonometry results can be used.
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Neha Singh, Jat. "Donor profile and trends of eye donation in Central India". International Journal of Clinical and Experimental Ophthalmology 5, n.º 1 (30 de abril de 2021): 005–8. http://dx.doi.org/10.29328/journal.ijceo.1001035.
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Background: The present study was conducted to study the donor profile and to assess the trends of cornea donation. Methodology: This was conducted as a hospital based cross sectional study at a tertiary care centre in Central India for a period of 5 years. Data was retrieved from 70 patients from eye bank who filled form of eye donation at Eye bank of our institution. Sociodemographic profile of donors, cause of death and time since death was recorded. Source of information regarding corneal donation and reason for not willing to donate the cornea for research purpose was recorded from the filled form. Further cornea enucleated were subjected to serology and their utilization for various purposes were recorded in questionnaire. Results: The present study retrieved data from a total of 70 donor forms with mean age of 65.84 ± 18.4 years. Cornea obtained from younger patients were mainly utilized for corneal transplantation whereas that from elderly age group > 60 years were mainly utilized for research/training purpose and the observed difference was statistically significant (p < 0.01). The corneas retrieved and utilized immediately after death were significantly used for optical or therapeutic purposes (p < 0.05). Conclusion: The present highlights the donor profile and trends of corneal donation at the tertiary care facility of Central India. It was observed that though the younger population and older population both are aware regarding corneal donation but still they are less aware on purpose for which cornea can be utilized. Quality of donor cornea is better when death to enucleation time interval was less.
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Guérin, Louis-Philippe, Gaëtan Le-Bel, Pascale Desjardins, Camille Couture, Elodie Gillard, Élodie Boisselier, Richard Bazin, Lucie Germain y Sylvain L. Guérin. "The Human Tissue-Engineered Cornea (hTEC): Recent Progress". International Journal of Molecular Sciences 22, n.º 3 (28 de enero de 2021): 1291. http://dx.doi.org/10.3390/ijms22031291.
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Each day, about 2000 U.S. workers have a job-related eye injury requiring medical treatment. Corneal diseases are the fifth cause of blindness worldwide. Most of these diseases can be cured using one form or another of corneal transplantation, which is the most successful transplantation in humans. In 2012, it was estimated that 12.7 million people were waiting for a corneal transplantation worldwide. Unfortunately, only 1 in 70 patients received a corneal graft that same year. In order to provide alternatives to the shortage of graftable corneas, considerable progress has been achieved in the development of living corneal substitutes produced by tissue engineering and designed to mimic their in vivo counterpart in terms of cell phenotype and tissue architecture. Most of these substitutes use synthetic biomaterials combined with immortalized cells, which makes them dissimilar from the native cornea. However, studies have emerged that describe the production of tridimensional (3D) tissue-engineered corneas using untransformed human corneal epithelial cells grown on a totally natural stroma synthesized by living corneal fibroblasts, that also show appropriate histology and expression of both extracellular matrix (ECM) components and integrins. This review highlights contributions from laboratories working on the production of human tissue-engineered corneas (hTECs) as future substitutes for grafting purposes. It overviews alternative models to the grafting of cadaveric corneas where cell organization is provided by the substrate, and then focuses on their 3D counterparts that are closer to the native human corneal architecture because of their tissue development and cell arrangement properties. These completely biological hTECs are therefore very promising as models that may help understand many aspects of the molecular and cellular mechanistic response of the cornea toward different types of diseases or wounds, as well as assist in the development of novel drugs that might be promising for therapeutic purposes.
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Alsmman Hassan, Alahmady Hamad y Nesreen Gamal-Eldeen Abd Elhaliem Soliman. "Intrastromal Injection of China Painting Ink in Corneas of Male Rabbits: Clinical and Histological Study". Journal of Ophthalmology 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/8145926.
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Background. Many patients with corneal opacity or complicated cataract in blind eye ask for cosmoses. In this study we tried to investigate the staining of corneas of male rabbits by Rotring China painting ink and to study the histological changes.Method. 10 eyes of 10 male Baladi Egyptian rabbits were injected (0.1 mL) intrastromally in the cornea by the use of China painting ink (Rotring Tinta China) through insulin syringe (27-gauge needle) by single injection; clinical follow-up is for 6 months and lastly the rabbits were scarified and the stained eyes were enucleated for histological analysis.Results. Clinically the stain was stable in color and distribution in corneas with no major complications. Histological results of the stained rabbit corneas showed blackish pigmentation in the corneal stroma without any inflammatory cellular infiltration. Some fibroblast cells had pigment granules in their cytoplasm in the adjacent layers.Conclusion. Corneal staining by China painting ink is effective and safe in staining of male rabbits cornea; however further study in human corneas with longer follow-up period is advisable.
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Wei, Junchao, Rui He, Xiaogang Wang, Yaowen Song, Jinhan Yao, Xiaona Liu, Xin Yang, Weiyi Chen y Xiaona Li. "The Corneal Ectasia Model of Rabbit: A Validity and Stability Study". Bioengineering 10, n.º 4 (16 de abril de 2023): 479. http://dx.doi.org/10.3390/bioengineering10040479.
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Keratoconus is a bilateral progressive degenerative corneal disease characterized by localized corneal thinning and dilatation. The pathogenesis of keratoconus is not fully elucidated. To gain a better understanding of the pathophysiology of this disease and to explore potential treatments, animal models are essential for basic research. Several attempts have been made to establish animal models of corneal ectasia by using collagenase. However, continuous changes of the cornea have not been well-tracked for the model. In this study, corneal morphology and biomechanical behavior in vivo were determined before and after collagenase Ⅱ treatment at 2, 4, and 8 weeks. The elastic modulus and histology of cornea tissues ex vivo were measured at 8 weeks postoperatively. The results showed that the posterior corneal curvature (Km B) increased and central corneal thickness (CCT) decreased after collagenase treatment. The mechanical properties of ectatic corneas weakened significantly and the collagen fiber interval in the stromal layer was increased and disorganized. This study provides insights into the changes of corneal morphology and biomechanical properties in a rabbit model of corneal ectasia. Changes observed at 8 weeks indicated that the cornea was still undergoing remodeling.
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Buela, Kristine-Ann y Robert Hendricks. "Corneal-derived dendritic cells are critical in T cell expansion after HSV-1 ocular infection (P6102)". Journal of Immunology 190, n.º 1_Supplement (1 de mayo de 2013): 128.3. http://dx.doi.org/10.4049/jimmunol.190.supp.128.3.
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Abstract Corneas possess resident DC (cornea-resident DC), and infiltrating DC migrate to the draining lymph nodes (DLN) following HSV-1 corneal infection (cornea-derived DC). The relative contribution of these two DC populations and DLN-resident DC to CD4+ and CD8+ T cell expansion in DLN following HSV-1 corneal infection is unknown. Local depletion of cornea-resident DC in CD11c-DTR mice did not affect T cell expansion in the DLN. Depletion of cornea-derived DC through 3 days post infection (dpi) abrogated early (3 dpi) CD8 T cell expansion (BrdU incorporation), but only reduced CD4 T cell expansion by 50%. Systemic DC depletion through 3 dpi completely abrogated expansion of both CD4 and CD8 T cells at 3 dpi. Depletion of cornea-derived DC through 7 dpi abrogated expansion of both CD4 and CD8 T cell at 7 dpi. Cornea-derived DC showed greater expression of CD70, CD80, and CD86 relative to DLN-resident DC. Blocking CD70 co-stimulation significantly reduced CD8 T cell survival and numbers, but did not affect their proliferation. We conclude that: (i) DC are required for expansion of both HSV-specific CD4+ and CD8+ T cells; (ii) up to 3 dpi CD8 T cells absolutely require HSV-1 presentation by cornea-derived DC possibly due to their enhanced costimulation, whereas DLN-resident DC can stimulate CD4 T cells (presumably with free virus that reaches the DLN from the cornea); (iii) after 3 dpi expansion of both CD4+ and CD8+ T cells requires transport of viral antigens by cornea-derived DC.
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Hall, Laurie R., Jonathan H. Lass, Eugenia Diaconu, Ellen R. Strine y Eric Pearlman. "An Essential Role for Antibody in Neutrophil and Eosinophil Recruitment to the Cornea: B Cell-Deficient (μMT) Mice Fail to Develop Th2-Dependent, Helminth-Mediated Keratitis". Journal of Immunology 163, n.º 9 (1 de noviembre de 1999): 4970–75. http://dx.doi.org/10.4049/jimmunol.163.9.4970.
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Abstract Invasion of the corneal stroma by neutrophils and eosinophils and subsequent degranulation disrupts corneal clarity and can result in permanent loss of vision. In the current study, we used a model of helminth-induced inflammation to demonstrate a novel role for Ab in mediating recruitment of these inflammatory cells to the central cornea. C57BL/6 and B cell-deficient (μMT) mice were immunized s.c. and injected intrastromally with Ags from the parasitic helminth Onchocerca volvulus (which causes river blindness). C57BL/6 mice developed pronounced corneal opacification, which was associated with an Ag-specific IL-5 response and peripheral eosinophilia, temporal recruitment of neutrophils and eosinophils from the limbal vessels to the peripheral cornea and subsequent migration to the central cornea. In contrast, the corneas of μMT mice failed to develop keratitis after intrastromal injection of parasite Ags unless Ags were injected with immune sera. Eosinophils were recruited from the limbal vessels to the peripheral cornea in μMT mice, but failed to migrate to the central cornea, whereas neutrophil recruitment was impaired at both stages. With the exception of IL-5, T cell responses and peripheral eosinophils were not significantly different between C57BL/6 and μMT mice. Taken together, these findings not only demonstrate that Ab is required for the development of keratitis, but also show that recruitment of neutrophils to the cornea is Ab-dependent, whereas eosinophil migration is only partially dependent upon Ab interactions.
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Fathy, Arwa, Bernardo T. Lopes, Renato Ambrósio, Richard Wu y Ahmed Abass. "The Efficiency of Using Mirror Imaged Topography in Fellow Eyes Analyses of Pentacam HR Data". Symmetry 13, n.º 11 (9 de noviembre de 2021): 2132. http://dx.doi.org/10.3390/sym13112132.
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Purpose: To investigate the effectiveness of flipping left corneas topography and analysethem quantitively along with fellow right corneas based on the assumption that they are mirror images of each other. Methods: The study involved scanning both eyes of 177 healthy participants (aged 35.3 ± 15.8) and 75 keratoconic participants (aged 33.9 ± 17.8). Clinical tomography data were collected for both eyes using the Pentacam HR and processed by a fully automated custom-built MATLAB code. For every case, the right eye was used as a datum fixed surface while the left cornea was flipped around in the superior–inferior direction. In this position, the root-mean-squared difference (RMS) between the flipped left cornea and the right cornea was initially determined for both the anterior and posterior corneal surfaces. Next, the iterative closest point transformation algorithm was applied on the three-dimensional flipped cornea to allow the flipped left corneal anterior surface to translate and rotate, minimising the difference between it and the right corneal anterior surface. Then, the RMS differences were recalculated and compared. Results: A comparison of the dioptric powers showed a significant difference between the RMS of both the flipped left eyes and the right eyes in the healthy and the KC groups (p < 0.001). The RMS of the surfaces of the flipped left corneas and the right corneas was 0.6 ± 0.4 D among the healthy group and 4.1 ± 2.3 among the KC group. After transforming the flipped left corneas, the RMS was recorded as 0.5 ± 0.3 D and 2.4 ± 2 D among the healthy and KC groups, respectively. Conclusions: Although fellow eyes are highly related in their clinical parameters, they should be treated with care when one eye topography is flipped and processed with the other eye topography in an optic-related research analysis where translation might be needed. In KC, an asymmetric disease, it was observed that a portion of the asymmetry was due to a corneal apex shift interfering with the image acquisition. Therefore, transforming the flipped left eyes by rotation and translation results in a fairer comparison between the fellow KC corneas.
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Shen, Yun-Zhi, Mi Xu y Song Sun. "In Vivo Confocal Microscopy Observation of Cell and Nerve Density in Different Corneal Regions with Monocular Pterygium". Journal of Ophthalmology 2020 (23 de marzo de 2020): 1–7. http://dx.doi.org/10.1155/2020/6506134.
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Purpose. To investigate the effects of pterygium on corneal cell and nerve density in patients with unilateral pterygium using in vivo laser scanning confocal microscopy (LSCM). Methods. In this cross-sectional study, 24 patients with unilateral pterygium who were treated in the Department of Ophthalmology of the Second People’s Hospital of Wuxi City from April 2018 to July 2018 were analyzed. Each eye with pterygium and its fellow eye were imaged by LSCM. The density of basal corneal epithelial cells, anterior stromal cells, posterior stromal cells, dendritic cells, and endothelial cells in pterygium and adjacent clear cornea was measured. In the fellow eyes, the central cornea, nasal cornea, nasal mid-peripheral cornea, and temporal cornea were imaged. The difference in the density of cells and subepithelial nerve fibers in different corneal regions of eyes with pterygium was analyzed. The cell and nerve density of the fellow cornea were also measured to exclude the influencing factors. Results. The density of corneal basal epithelial cells in the central corneas of eyes with pterygium was 6497 ± 1776 cells/mm2, which was higher than that in the area near the head of pterygium (5580 ± 1294 cells/mm2, P<0.001), the region above pterygium (6097 ± 1281 cells/mm2, P=0.049), and the region below pterygium (5463 ± 1007 cells/mm2, P=0.001). The density of anterior stromal cells in the central cornea was 742 ± 243 cells/mm2, which was higher than that in the area near the head of pterygium (587 ± 189 cells/mm2, P=0.005), the region below pterygium (492 ± 159 cells/mm2, P=0.005), and the temporal cornea (574 ± 164 cells/mm2, P=0.003). The density of endothelial cells in the central cornea was 2398 ± 260 cells/mm2, which was higher than that in the area near the head of pterygium (2296 ± 231 cells/mm2, P=0.011) and the region below pterygium (2272 ± 400 cells/mm2, P=0.020). The density of dendritic cells in the central cornea was 53 ± 48 cells/mm2, which was lower than that in the area near the head of pterygium (250 ± 224 cells/mm2, P=0.001), the upper region (103 ± 47 cells/mm2, P=0.006), and the lower region (90 ± 48 cells/mm2, P=0.023). The corneal nerve fiber length (CNFL) in the center was higher than that in the area near the head of pterygium, the upper region, and the lower region. Compared with fellow eyes, eyes with pterygium had a significantly higher mean corneal power (KM) (P<0.001). There was a significant positive linear relationship between the corneal area invaded by pterygium of pterygia and KM (r = 0.609, P=0.009). Conclusion. Basal epithelial cells, stromal cells, endothelial cells, dendritic cells, and subepithelial nerve fibers in the central cornea of eyes with pterygium were different from those of pterygium and adjacent clear cornea. LSCM is effective for observing the morphology and quantity of corneal cells in pterygium.
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Suh, Ji Hyung, Ik Hee Ryu, Jin Pyo Hong, Ja Yoon Moon, Jin Seok Choi, Ikhyun Jun, Tae-Im Kim y Eung Kweon Kim. "Phenotypes of Granular Corneal Dystrophy Type 2 among Koreans in Their Twenties". Journal of the Korean Ophthalmological Society 63, n.º 12 (15 de diciembre de 2022): 965–72. http://dx.doi.org/10.3341/jkos.2022.63.12.965.
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Purpose: Granular corneal dystrophy type 2 (GCD2) is a hereditary disease that features granular and lattice stromal deposits in the cornea. There are homozygotes and heterozygotes and the opacities are exacerbated by corneal trauma or surgery, such as laser in situ keratomileusis (LASIK). As there is individual variability in GCD2 phenotypes, we investigated various corneal features of GCD2 patients in their twenties, the main age group for refractive surgery.Methods: From genetically confirmed GCD2 patients who had an R124H mutation of the transforming growth factor β induced (<i>TGFBI</i>) gene at age 20 to 29 years, we chose representative patients: one homozygote; one compound heterozygote; one simple heterozygote with a severe phenotype with many granular deposits; one common heterozygote; and four heterozygotes with normal corneas. The corneas of all patients were subject to slit-lamp examination and photographed.Results: The homozygote had confluent granular deposits covering the cornea. The compound heterozygote had granular and lattice deposits covering the center of the cornea. The patient with a severe phenotype had more than 30 granular deposits in one eye, but was a simple GCD2 heterozygote, verified by full-sequencing of the <i>TGFBI</i> gene. In the four patients with normal corneas, a single small lesion was subsequently detected during follow-up in two, at 3 weeks and 6 months, respectively. Both corneas were judged clear at chance examinations.Conclusions: Among Koreans in their twenties, GCD2 patients have various phenotypes, from clear corneas to severe confluent opacities. There are GCD2 heterozygotes with nearly clear corneas, so caution must be taken when choosing patients for refractive surgery.
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Avetisov, S. E., A. A. Tyurina, Z. V. Surnina, O. M. Dovgileva y E. V. Sukhanova. "Morphometric Analysis of Corneal Nerves Condition after Laser Keratorefractive Surgery". Ophthalmology in Russia 16, n.º 1S (22 de abril de 2019): 27–32. http://dx.doi.org/10.18008/1816-5095-2019-1s-27-32.
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Purpose: to conduct a morphometric assessment of the corneal nerves state after laser keratorefractive surgery using laser confocal microscopy and the software Liner 1.2S. Patients and methods. 40 eyes of 20 patients received LASIK to correct a mean refractive error of –4.5 ± 1.9 diopters (range, –2.25 to –8.25 diopters). The stroma was ablated with a Teneo Technolas 317P excimer laser. Corneas were examined by laser corneal confocal microscopy (HRT III with Rostock Cornea Module) before and in 1, 3, and 6 months after LASIK. Images were analyzed with software that automatically computes coefficients of anisotropy and orientation symmetry of corneal nerves. Result. At 1 and 3 months after surgery, the center corneal nerves were completely absent. At 1, 3 and 6 months after surgery, the paracentral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. At 6 months after surgery, both central and peripheral corneal nerves were detected and the coefficient of anisotropy were statistically significantly reduced compared with the preoperative rates. Conclusion. As a result of the study, the central corneal nerves were first detected at 6 months after surgery, whereas the paracentral cornea nerves were detected already after 1 month. At 6 months after surgery, the coefficient of anisotropy in the central of cornea statistically significant decreased compared to the preoperative rates. At all stages of the study after surgery, the anisotropy coefficient in the cornea paracentral statistically significant decreased compared with preoperative.
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Safi, Tarek, Loay Daas, Gian-Luca Kiefer, Mansi Sharma, Alassane Ndiaye, Matthieu Deru, Jan Alexandersson y Berthold Seitz. "Semiquantitative Criteria in the Eye Bank That Correlate with Cornea Guttata in Donor Corneas". Klinische Monatsblätter für Augenheilkunde 238, n.º 06 (junio de 2021): 680–87. http://dx.doi.org/10.1055/a-1498-1846.
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Abstract Background Cornea guttata may not be recognized in the eye bank and recent studies have displayed that guttae are transplanted in about 15% of cases in varying severities. The purpose of this study was to establish semiquantitative criteria for the detection of cornea guttata in donor corneas in the eye bank. Methods In this retrospective cohort study, preoperative endothelial pictures of donor corneas were collected and classified according to the post-penetrating keratoplasty cornea guttata grade into three distinct groups: group 1 consists of healthy corneas with no guttae (guttata grade 0); group 2 constitutes corneas with mild asymptomatic cornea guttata (guttata grade +); and group 3 comprises corneas with advanced widespread cornea guttata (guttata grade ++/+++/++++). The preoperative pictures of each group were then individually analyzed using the following five semiquantitative criteria: The number and the area of the cell-depleted surfaces, the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions, the presence of blebs in the cell membrane, and the presence of groups of cells with a distinct whitish color. Results In total, 262 patients were included in this study, with a total number of 1582 preoperative donor corneal endothelial pictures. Out of those pictures, groups 1, 2, and 3 encompassed 995 (62.9%), 411 (26.0%), and 176 (11.1%) pictures, respectively. Three out of the five eye bank criteria were found to correlate with postoperative cornea guttata with a highly significant p value of < 0.001. These three criteria are the presence of less than 50% of the cells having a hexagonal or a circular shape, the presence of cell membrane defects and interruptions and, the presence of blebs. The presence of groups of cells with a distinct whitish color was only a weak predictive factor for cornea guttata (p = 0.069). There was no statistically significant correlation between the number and the area of cell-depleted surfaces and postoperative cornea guttata with a p = 0.181. Conclusion Three semiquantitative criteria that can be detected in the eye bank using inverted light microscopy seem to correlate with postoperative cornea guttata: The presence of blebs, the presence of cell membrane defects and interruptions, as well as endothelial pictures with less than 50% of the cells having a hexagonal of circular shape. The presence of groups of cells with a distinct whitish color appears to be a weak predictor of cornea guttata.
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Hashimoto, Yoshihide. "Research and development on therapeutic materials for corneal stromal disease consisting of transparent decellularised porcine corneas". Impact 2023, n.º 3 (21 de septiembre de 2023): 49–51. http://dx.doi.org/10.21820/23987073.2023.3.49.
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Investigations to discover potential corneal stromal substitutes to effectively treat corneal stromal disease tend to focus on transparent and bio-inert synthetic polymer materials and hydrogel materials. More recent studies are looking at alternative therapeutic materials that utilise corneas from pigs. Assistant Professor Yoshihide Hashimoto, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Japan, is part of a team developing functional materials and therapeutic techniques to restore the function of damaged biological tissues and organs based on biomaterials and bioengineering. At present, the researchers are focused on restoring the function of corneas, but the research has the potential for broader applications. After blindness caused by clouding or shape change, corneal transplantation is the only effective treatment but there is a worldwide shortage of donated human corneas. To establish an advanced treatment for corneal diseases in combination with cell therapy, reliable artificial corneal stroma is required and Hashimoto and the team are exploring the potential of highly transparent decellularised porcine cornea for the treatment of corneal stroma disease. This has potential to overcome the issues associated with existing treatments and can also be developed for reconstruction of full-thickness cornea. In decellularised corneas, cellular components are removed from animal-derived corneal tissue. The method the team is using does not use surfactants, which means the functional proteins and tissue structure can be retained.
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Kiliç, Kaya, Deniz Konya, Özlem Kurtkaya, Aydin Sav, M. Necmettin Pamir y Türker Kiliç. "Inhibition of angiogenesis induced by cerebral arteriovenous malformations using Gamma Knife irradiation". Journal of Neurosurgery 106, n.º 3 (marzo de 2007): 463–69. http://dx.doi.org/10.3171/jns.2007.106.3.463.
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Object The authors studied the effect of Gamma Knife irradiation on angiogenesis induced by cerebral arteriovenous malformation (AVM) tissues implanted in the corneas of rats. Methods Ten AVM specimens obtained from tissue resections performed at Marmara University between 1998 and 2004 were used. A uniform amount of tissue was implanted into the micropocket between the two epithelial layers of the cornea. Gamma Knife irradiation was applied with dose prescriptions of 15 or 30 Gy to one cornea at 100% iso-dose. Dosing was adjusted so that the implanted cornea of one eye received 1.5 Gy when 15 Gy was applied to the other cornea. Similarly, one cornea received 3 Gy when 30 Gy was applied to the other cornea. Angiogenic activity was graded daily by biomicroscopic observations. Forty-eight other rats were used for microvessel counting and vascularendothelial growth factor (VEGF) staining portions of the experiment. Micropieces of the specimens were again used for corneal implantation. Rats from each group were killed on Days 5, 10, 15, and 20, and four corneas from each group were examined. Gamma Knife irradiation dose dependently decreased AVM-induced neovascularization in the rat cornea as determined by biomicroscopic grading of angiogenesis, microvessel count, and VEGF expression. Conclusions The results suggest that Gamma Knife irradiation inhibits angiogenesis induced by AVM tissue in the cornea angiogenesis model. The data are not directly related to understanding how Gamma Knife irradiation occludes existing AVM vasculature, but to understanding why properly treated AVMs do not recur and do not show neovascularization after Gamma Knife irradiation.
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Hussain, Noor Ahmed, Francisco C. Figueiredo y Che J. Connon. "Use of biomaterials in corneal endothelial repair". Therapeutic Advances in Ophthalmology 13 (enero de 2021): 251584142110582. http://dx.doi.org/10.1177/25158414211058249.
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Human corneal endothelium (HCE) is a single layer of hexagonal cells that lines the posterior surface of the cornea. It forms the barrier that separates the aqueous humor from the rest of the corneal layers (stroma and epithelium layer). This layer plays a fundamental role in maintaining the hydration and transparency of the cornea, which in turn ensures a clear vision. In vivo, human corneal endothelial cells (HCECs) are generally believed to be nonproliferating. In many cases, due to their nonproliferative nature, any damage to these cells can lead to further issues with Descemet’s membrane (DM), stroma and epithelium which may ultimately lead to hazy vision and blindness. Endothelial keratoplasties such as Descemet’s stripping automated endothelial keratoplasty (DSAEK) and Descemet’s membrane endothelial keratoplasty (DEK) are the standard surgeries routinely used to restore vision following endothelial failure. Basically, these two similar surgical techniques involve the replacement of the diseased endothelial layer in the center of the cornea by a healthy layer taken from a donor cornea. Globally, eye banks are facing an increased demand to provide corneas that have suitable features for transplantation. Consequently, it can be stated that there is a significant shortage of corneal grafting tissue; for every 70 corneas required, only 1 is available. Nowadays, eye banks face long waiting lists due to shortage of donors, seriously aggravated when compared with previous years, due to the global COVID-19 pandemic. Thus, there is an urgent need to find alternative and more sustainable sources for treating endothelial diseases, such as utilizing bioengineering to use of biomaterials as a remedy. The current review focuses on the use of biomaterials to repair the corneal endothelium. A range of biomaterials have been considered based on their promising results and outstanding features, including previous studies and their key findings in the context of each biomaterial.
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Procházková, Alexandra, Martina Poláchová, Jakub Dítě, Magdaléna Netuková y Pavel Studený. "Chemical, Physical, and Biological Corneal Decellularization Methods: A Review of Literature". Journal of Ophthalmology 2024 (25 de marzo de 2024): 1–17. http://dx.doi.org/10.1155/2024/1191462.
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The cornea is one of the most commonly transplanted tissues worldwide. It is used to restore vision when severe visual impairment or blindness occurs in patients with corneal diseases or after trauma. Due to the global shortage of healthy donor corneas, decellularized corneal tissue has significant potential as an alternative to corneal transplantation. It preserves the native and biological ultrastructure of the cornea and, therefore, represents the most promising scaffold. This article discusses different methods of corneal decellularization based on the current literature. We searched PubMed.gov for articles from January 2009 to December 2023 using the following keywords: corneal decellularization, decellularization methods, and corneal transplantation. Although several methods of decellularization of corneal tissue have been reported, a universal standardised protocol of corneal decellularization has not yet been introduced. In general, a combination of decellularization methods has been used for efficient decellularization while preserving the optimal properties of the corneal tissue.
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Liu, Yang, Chuanlei Zhang, Yanhui Kong, Huiyu Liu, Cheng Chen, Wenyu Gao, Xiaowei Xi, Hui Yang y Linhong Deng. "Preparation and Characterization of a Photo-Crosslinked Methacryloyl-Collagen Composite Film to Promote Corneal Nerve Regeneration via Surface Grafting of Taurine Molecules". International Journal of Molecular Sciences 24, n.º 14 (8 de julio de 2023): 11248. http://dx.doi.org/10.3390/ijms241411248.
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Blindness is frequently caused by corneal abnormalities, and corneal transplantation is the most effective treatment method. It is extremely important to develop high-quality artificial corneas because there are not enough donor corneas accessible for cornea transplantation. One of the most-often utilized materials is collagen, which is the primary component of natural cornea. Collagen-based corneal repair materials have good physicochemical properties and excellent biocompatibility, but how to promote the regeneration of the corneal nerve after keratoplasty is still a big challenge. In this research, in order to promote the growth of nerve cells on a collagen (Col) substrate, a novel collagen-based material was synthesized starting from the functionalization of collagen with unsaturated methacryloyl groups that three-dimensionally photopolymerize to a 3D network of chemically crosslinked collagen (ColMA), onto which taurine molecules were eventually grafted (ColMA-Tr). The physicochemical properties and biocompatibility of the Col, ColMA and ColMA-Tr films were evaluated. By analyzing the results, we found that all the three samples had good moisture retention and aq high covalent attachment of methacryloyl groups followed by their photopolymerization improved the mechanical properties of the ColMA and ColMA-Tr. Most importantly, compared with ColMA, the taurine-modified collagen-MA film significantly promoted the growth of nerve cells and corneal epithelial cells on its surface. Our preliminary results suggest that this novel ColMA-Tr film may have potential use in cornea tissue engineering in the future.
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Kling, Sabine, Imran B. Akca, Ernest W. Chang, Giuliano Scarcelli, Nandor Bekesi, Seok-Hyun Yun y Susana Marcos. "Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties". Journal of The Royal Society Interface 11, n.º 101 (6 de diciembre de 2014): 20140920. http://dx.doi.org/10.1098/rsif.2014.0920.
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Most techniques measuring corneal biomechanics in vivo are biased by side factors. We demonstrate the ability of optical coherence tomographic (OCT) vibrography to determine corneal material parameters, while reducing current prevalent restrictions of other techniques (such as intraocular pressure (IOP) and thickness dependency). Modal analysis was performed in a finite-element (FE) model to study the oscillation response in isolated thin corneal flaps/eye globes and to analyse the dependency of the frequency response function on: corneal elasticity, viscoelasticity, geometry (thickness and curvature), IOP and density. The model was verified experimentally in flaps from three bovine corneas and in two enucleated porcine eyes using sound excitation (100–110 dB) together with a phase-sensitive OCT to measure the frequency response function (range 50–510 Hz). Simulations showed that corneal vibration in flaps is sensitive to both, geometrical and biomechanical parameters, whereas in whole globes it is primarily sensitive to corneal biomechanical parameters only. Calculations based on the natural frequency shift revealed that flaps of the posterior cornea were 0.8 times less stiff than flaps from the anterior cornea and cross-linked corneas were 1.6 times stiffer than virgin corneas. Sensitivity analysis showed that natural vibration frequencies of whole globes were nearly independent from corneal thickness and IOP within the physiological range. OCT vibrography is a promising non-invasive technique to measure corneal elasticity without biases from corneal thickness and IOP.
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Kling, Sabine. "Optical coherence elastography by ambient pressure modulation for high-resolution strain mapping applied to patterned cross-linking". Journal of The Royal Society Interface 17, n.º 162 (enero de 2020): 20190786. http://dx.doi.org/10.1098/rsif.2019.0786.
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The purpose of this study was to develop a novel non-contact optical coherence elastography (OCE) approach to measure laterally and axially highly resolved corneal strain distribution at different stages of patterned corneal cross-linking (CXL). Freshly enucleated rat eyes were obtained and prepared for accelerated patterned CXL treatment with distinct ultraviolet (UV) patterns (central, peripheral, bow-tie irradiation). Each cornea was measured repeatedly, in three different conditions: (i) virgin, (ii) after epithelial debridement and 0.5% hypo-osmolar riboflavin instillation for 30 min, and (iii) after patterned CXL at 9 mW cm −2 for 10 min. For biomechanical assessment, the corneal deformation response to an ambient pressure variation of −2 mmHg was recorded by OCE. Strain maps were obtained from phase and magnitude changes in the complex optical coherence tomography signal. Virgin corneas presented negative strain (−2.7 ± 1.1‰) in the anterior cornea and positive strain (1.9 ± 1.3‰) in the posterior cornea. A pronounced shift towards positive strains in the anterior cornea (particularly in UV-irradiated regions) was observed after CXL. Patterned UV irradiation induced localized strain alterations closely matching the geometry of the irradiation pattern. This study demonstrates the possibility of non-contact OCE by ambient pressure modulation, which could substantially improve the early diagnosis of corneal degeneration, advance research in small-animal eyes and refine in vitro mechanical investigation.
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Schultz, C. L., A. G. Buret, M. E. Olson, H. Ceri, R. R. Read y D. W. Morck. "Lipopolysaccharide Entry in the Damaged Cornea and Specific Uptake by Polymorphonuclear Neutrophils". Infection and Immunity 68, n.º 3 (1 de marzo de 2000): 1731–34. http://dx.doi.org/10.1128/iai.68.3.1731-1734.2000.
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ABSTRACT Bacterial lipopolysaccharide (LPS) is an important agent of induction of ocular pathology following corneal injury or wearing of contaminated contact lenses. The mechanism of LPS uptake through the corneal epithelium is unclear, and the role played by inflammatory cells in this phenomenon has not been previously assessed. Fluorescein isothiocyanate-labeled LPS from Escherichia coli was deposited onto the abraded corneas of New Zealand White rabbits. Epifluorescence microscopy of living excised corneas revealed diffuse LPS staining in the epithelial and stromal layers only in the vicinity of the abrasion. In addition, specific cellular uptake of LPS was suggested by fluorescence staining of cells along the abrasion site. In a second series of experiments, an anti-CD18 polyclonal antibody was used to block infiltration of polymorphonuclear neutrophils (PMN) into the cornea. In these experiments, a diffuse distribution of fluorescent LPS was still observed along the abrasion, but the specific cellular uptake was abolished. The findings indicate that LPS enters the cornea via diffuse penetration at sites of injury and that specific cellular uptake of LPS occurs within the cornea via PMN which have migrated into the damaged tissue.
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Gimenes, Izabela, Andréa V. Braga Pintor, Mariana da Silva Sardinha, Guido A. Marañón-Vásquez, Marcelo Salabert Gonzalez, Octavio Augusto França Presgrave, Lucianne Cople Maia y Gutemberg Gomes Alves. "Cold Storage Media versus Optisol-GS in the Preservation of Corneal Quality for Keratoplasty: A Systematic Review". Applied Sciences 12, n.º 14 (13 de julio de 2022): 7079. http://dx.doi.org/10.3390/app12147079.
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Optisol-GS is the most widely used pharmaceutical composition to preserve corneas for transplantation. This systematic review investigated the effects of different cold corneal storage media (CCSM) compared with Optisol-GS on the quality of stored corneas. The literature was searched throughout May 2022 on six databases and grey literature. Studies including corneas (population) exposed to distinct cold storage media (exposure) and Optisol-GS (comparison) that reported qualitative and/or quantitative parameters of cornea quality (outcome) were included. Methodological quality was assessed using ToxRTool. From 4520 identified studies, fourteen were included according to the eligibility criteria, comprising 769 evaluated cornea samples comparing Optisol-GS with commercial and noncommercial media. All studies showed good methodological quality. Experimental times ranged from 1–28 days, mainly using 4 °C as the preservation temperature. Viable endothelial cell density (ECD) and endothelial cell morphology (EC) were the most assessed parameters. ECD results for Cornisol were higher than Optisol-GS in 10 days (p = 0.049) and favored Cornea ColdTM up to 4 weeks (p < 0.05), which also showed better qualitative results. While the standardization of test protocols could improve comparisons, evidence indicates that most CCSM present similar performances on cornea preservation for transplantation at seven days, while some formulations may increase preservation at extended times.
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Twardy, Brandon, Rudragouda Channappanavar y Susmit Suvas. "Herpetic Stromal Keratitis (HSK) lesion severity correlates with the amount of pro-inflammatory neuropeptide Substance P in the cornea (42.21)". Journal of Immunology 184, n.º 1_Supplement (1 de abril de 2010): 42.21. http://dx.doi.org/10.4049/jimmunol.184.supp.42.21.
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Abstract The cornea is richly supplied by nerve fibers that express a variety of biologically active neuropeptides. In this report, we looked into the possibility that after ocular herpes simplex virus-1 (HSV-1) infection of C57BL/6, the level of expression of neuropeptide SP in the cornea correlates with the development of HSK lesions. Our results showed that after ocular HSV-1 infection of C57BL/6 mice, about 60-70% of the infected corneas developed severe HSK lesions (corneal opacity ≥3 and angiogenesis ≥8) whereas, 30-40% developed mild HSK lesions (corneal opacity ≤1 and angiogenesis ≤5). No significant difference in the viral load was determined when analyzed between the corneas with mild or severe HSK lesions at different time-points post-infection. However, a strong influx of CD4 T cells and neutrophils were evident in the corneas with severe HSK lesions when compared to those with mild lesions at day 15 post-infection. In addition, corneas with mild HSK lesions had lower levels of IL-6, IL-2, IFN-g and IL-1 Ra in comparison to the corneas with severe HSK lesions as determined on day 15 post-infection. Most importantly, corneas with severe HSK lesions had significantly higher levels of neuropeptide SP in comparison those with mild HSK lesions, when determined on day 15 post-infection by using Immunofluorescence and EIA technique. We are looking into the possibility that neutralization of SP in the cornea impedes the development of severe HSK lesions in a mouse model.