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Köry J, Stewart PS, Hill NA, Luo XY, Pandolfi A. A discrete-to-continuum model for the human cornea with application to keratoconus. ROYAL SOCIETY OPEN SCIENCE 2024; 11:240265. [PMID: 39050729 PMCID: PMC11265872 DOI: 10.1098/rsos.240265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 05/02/2024] [Indexed: 07/27/2024]
Abstract
We introduce a discrete mathematical model for the mechanical behaviour of a planar slice of human corneal tissue, in equilibrium under the action of physiological intraocular pressure (IOP). The model considers a regular (two-dimensional) network of structural elements mimicking a discrete number of parallel collagen lamellae connected by proteoglycan-based chemical bonds (crosslinks). Since the thickness of each collagen lamella is small compared to the overall corneal thickness, we upscale the discrete force balance into a continuum system of partial differential equations and deduce the corresponding macroscopic stress tensor and strain energy function for the micro-structured corneal tissue. We demonstrate that, for physiological values of the IOP, the predictions of the discrete model converge to those of the continuum model. We use the continuum model to simulate the progression of the degenerative disease known as keratoconus, characterized by a localized bulging of the corneal shell. We assign a spatial distribution of damage (i.e. reduction of the stiffness) to the mechanical properties of the structural elements and predict the resulting macroscopic shape of the cornea, showing that a large reduction in the element stiffness results in substantial corneal thinning and a significant increase in the curvature of both the anterior and posterior surfaces.
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Affiliation(s)
- J. Köry
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - P. S. Stewart
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - N. A. Hill
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - X. Y. Luo
- School of Mathematics and Statistics, University of Glasgow, Glasgow G12 8QQ, UK
| | - A. Pandolfi
- Department of Civil and Environmental Engineering, Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy
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2
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Meek KM, Knupp C, Lewis PN, Morgan SR, Hayes S. Structural control of corneal transparency, refractive power and dynamics. Eye (Lond) 2024:10.1038/s41433-024-02969-7. [PMID: 38396030 DOI: 10.1038/s41433-024-02969-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/11/2023] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
The cornea needs to be transparent to visible light and precisely curved to provide the correct refractive power. Both properties are governed by its structure. Corneal transparency arises from constructive interference of visible light due to the relatively ordered arrangement of collagen fibrils in the corneal stroma. The arrangement is controlled by the negatively charged proteoglycans surrounding the fibrils. Small changes in fibril organisation can be tolerated but larger changes cause light scattering. Corneal keratocytes do not scatter light because their refractive index matches that of the surrounding matrix. When activated, however, they become fibroblasts that have a lower refractive index. Modelling shows that this change in refractive index significantly increases light scatter. At the microscopic level, the corneal stroma has a lamellar structure, the parallel collagen fibrils within each lamella making a large angle with those of adjacent lamellae. X-ray scattering has shown that the lamellae have preferred orientations in the human cornea: inferior-superior and nasal-temporal in the central cornea and circumferential at the limbus. The directions at the centre of the cornea may help withstand the pull of the extraocular muscles whereas the pseudo-circular arrangement at the limbus supports the change in curvature between the cornea and sclera. Elastic fibres are also present; in the limbus they contain fibrillin microfibrils surrounding an elastin core, whereas at the centre of the cornea, they exist as thin bundles of fibrillin-rich microfibrils. We present a model based on the structure described above that may explain how the cornea withstands repeated pressure changes due to the ocular pulse.
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Affiliation(s)
- Keith M Meek
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Carlo Knupp
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Siân R Morgan
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Sally Hayes
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
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Volatier T, Cursiefen C, Notara M. Current Advances in Corneal Stromal Stem Cell Biology and Therapeutic Applications. Cells 2024; 13:163. [PMID: 38247854 PMCID: PMC10814767 DOI: 10.3390/cells13020163] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/08/2024] [Accepted: 01/12/2024] [Indexed: 01/23/2024] Open
Abstract
Corneal stromal stem cells (CSSCs) are of particular interest in regenerative ophthalmology, offering a new therapeutic target for corneal injuries and diseases. This review provides a comprehensive examination of CSSCs, exploring their anatomy, functions, and role in maintaining corneal integrity. Molecular markers, wound healing mechanisms, and potential therapeutic applications are discussed. Global corneal blindness, especially in more resource-limited regions, underscores the need for innovative solutions. Challenges posed by corneal defects, emphasizing the urgent need for advanced therapeutic interventions, are discussed. The review places a spotlight on exosome therapy as a potential therapy. CSSC-derived exosomes exhibit significant potential for modulating inflammation, promoting tissue repair, and addressing corneal transparency. Additionally, the rejuvenation potential of CSSCs through epigenetic reprogramming adds to the evolving regenerative landscape. The imperative for clinical trials and human studies to seamlessly integrate these strategies into practice is emphasized. This points towards a future where CSSC-based therapies, particularly leveraging exosomes, play a central role in diversifying ophthalmic regenerative medicine.
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Affiliation(s)
- Thomas Volatier
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
| | - Claus Cursiefen
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
- Cologne Excellence Cluster for Cellular Stress Responses Aging-Associated Diseases (CECAD), University of Cologne, Joseph-Stelzmann-Strasse 26, 50931 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
| | - Maria Notara
- Department of Ophthalmology, Faculty of Medicine, University Hospital Cologne, University of Cologne, 50937 Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), Faculty of Medicine, University Hospital Cologne, University of Cologne, 50931 Cologne, Germany
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4
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Abdalkader RK, Fujita T. Corneal epithelium models for safety assessment in drug development: Present and future directions. Exp Eye Res 2023; 237:109697. [PMID: 37890755 DOI: 10.1016/j.exer.2023.109697] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 10/18/2023] [Accepted: 10/24/2023] [Indexed: 10/29/2023]
Abstract
The human corneal epithelial barrier plays a crucial role in drug testing studies, including drug absorption, distribution, metabolism, and excretion (ADME), as well as toxicity testing during the preclinical stages of drug development. However, despite the valuable insights gained from animal and current in vitro models, there remains a significant discrepancy between preclinical drug predictions and actual clinical outcomes. Additionally, there is a growing emphasis on adhering to the 3R principles (refine, reduce, replace) to minimize the use of animals in testing. To tackle these challenges, there is a rising demand for alternative in vitro models that closely mimic the human corneal epithelium. Recently, remarkable advancements have been made in two key areas: microphysiological systems (MPS) or organs-on-chips (OoCs), and stem cell-derived organoids. These cutting-edge platforms integrate four major disciplines: stem cells, microfluidics, bioprinting, and biosensing technologies. This integration holds great promise in developing powerful and biomimetic models of the human cornea.
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Affiliation(s)
- Rodi Kado Abdalkader
- Ritsumeikan Global Innovation Research Organization (R-GIRO), Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577, Japan.
| | - Takuya Fujita
- Ritsumeikan Global Innovation Research Organization (R-GIRO), Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577, Japan; Department of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-Higashi, Kusatsu, Shiga, 525-8577, Japan
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Dua HS, Freitas R, Mohammed I, Ting DSJ, Said DG. The pre-Descemet's layer (Dua's layer, also known as the Dua-Fine layer and the pre-posterior limiting lamina layer): Discovery, characterisation, clinical and surgical applications, and the controversy. Prog Retin Eye Res 2023; 97:101161. [PMID: 36642673 DOI: 10.1016/j.preteyeres.2022.101161] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 12/22/2022] [Accepted: 12/28/2022] [Indexed: 01/15/2023]
Abstract
The pre-Descemet's layer/Dua's layer, also termed the Dua-Fine layer and the pre-posterior limiting lamina layer, lies anterior to the Descemet's membrane in the cornea, is 10 μm (range 6-16) thick, made predominantly of type I and some type VI collagen with abundant elastin, more than any other layer of the cornea. It has high tensile strength (bursting pressure up to 700 mm of Hg), is impervious to air and almost acellular. At the periphery it demonstrates fenestrations and ramifies to become the core of the trabecular meshwork, with implications for intraocular pressure and glaucoma. It has been demonstrated in some species of animals. The layer has assumed considerable importance in anterior and posterior lamellar corneal transplant surgery by improving our understanding of the behaviour of corneal tissue during these procedures, improved techniques and made the surgery safer with better outcomes. It has led to the innovation of new surgical procedures namely, pre-Descemet's endothelial keratoplasty, suture management of acute hydrops, DALK-triple and Fogla's mini DALK. The discovery and knowledge of the layer has introduced paradigm shifts in our age old concepts of Descemet's membrane detachment, acute corneal hydrops in keratoconus and Descemetoceles, with impact on management approaches. It has been shown to contribute to the pathology and clinical signs observed in corneal infections and some corneal dystrophies. Early evidence suggests that it may have a role in the pathogenesis of keratoconus in relation to its elastin content. Its contribution to corneal biomechanics and glaucoma are subjects of current investigations.
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Affiliation(s)
- Harminder S Dua
- Larry A Donoso Laboratory for Eye Research, Academic Unit of Ophthalmology and Visual Sciences, University of Nottingham, The Queens Medical Centre, Nottingham University Hospitals, NHS Trust, Nottingham, England, UK.
| | - Rui Freitas
- Larry A Donoso Laboratory for Eye Research, Academic Unit of Ophthalmology and Visual Sciences, University of Nottingham, The Queens Medical Centre, Nottingham University Hospitals, NHS Trust, Nottingham, England, UK; Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Portugal.
| | - Imran Mohammed
- Larry A Donoso Laboratory for Eye Research, Academic Unit of Ophthalmology and Visual Sciences, University of Nottingham, The Queens Medical Centre, Nottingham University Hospitals, NHS Trust, Nottingham, England, UK.
| | - Darren S J Ting
- Larry A Donoso Laboratory for Eye Research, Academic Unit of Ophthalmology and Visual Sciences, University of Nottingham, The Queens Medical Centre, Nottingham University Hospitals, NHS Trust, Nottingham, England, UK.
| | - Dalia G Said
- Larry A Donoso Laboratory for Eye Research, Academic Unit of Ophthalmology and Visual Sciences, University of Nottingham, The Queens Medical Centre, Nottingham University Hospitals, NHS Trust, Nottingham, England, UK; Research Institute of Ophthalmology, Cairo, Egypt.
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Jaskiewicz K, Maleszka-Kurpiel M, Matuszewska E, Kabza M, Rydzanicz M, Malinowski R, Ploski R, Matysiak J, Gajecka M. The Impaired Wound Healing Process Is a Major Factor in Remodeling of the Corneal Epithelium in Adult and Adolescent Patients With Keratoconus. Invest Ophthalmol Vis Sci 2023; 64:22. [PMID: 36811882 PMCID: PMC9970004 DOI: 10.1167/iovs.64.2.22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Purpose Keratoconus (KTCN) is the most common corneal ectasia, characterized by pathological cone formation. Here, to provide an insight into the remodeling of the corneal epithelium (CE) during the course of the disease, we evaluated topographic regions of the CE of adult and adolescent patients with KTCN. Methods The CE samples from 17 adult and 6 adolescent patients with KTCN, and 5 control CE samples were obtained during the CXL and PRK procedures, respectively. Three topographic regions, central, middle, and peripheral, were separated toward RNA sequencing and MALDI-TOF/TOF Tandem Mass Spectrometry. Data from transcriptomic and proteomic investigations were consolidated with the morphological and clinical findings. Results The critical elements of the wound healing process, epithelial-mesenchymal transition, cell-cell communications, and cell-extracellular matrix interactions were altered in the particular corneal topographic regions. Abnormalities in pathways of neutrophils degranulation, extracellular matrix processing, apical junctions, IL, and IFN signaling were revealed to cooperatively disorganize the epithelial healing. Deregulation of the epithelial healing, G2M checkpoints, apoptosis, and DNA repair pathways in the middle CE topographic region in KTCN explains the presence of morphological changes in the corresponding doughnut pattern (a thin cone center surrounded by a thickened annulus). Despite similar morphological characteristics of CE samples in adolescents and adults with KTCN, their transcriptomic features were different. Values of the posterior corneal elevation differentiated adults with KTCN from adolescents with KTCN and correlated with the expression of TCHP, SPATA13, CNOT3, WNK1, TGFB2, and KRT12 genes. Conclusions Identified molecular, morphological, and clinical features indicate the effect of impaired wound healing on corneal remodeling in KTCN CE.
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Affiliation(s)
| | - Magdalena Maleszka-Kurpiel
- Optegra Eye Health Care Clinic in Poznan, Poznan, Poland,Department of Optometry, Chair of Ophthalmology and Optometry, Poznan University of Medical Sciences, Poznan, Poland
| | - Eliza Matuszewska
- Chair and Department of Inorganic and Analytical Chemistry, Poznan University of Medical Sciences, Poznan, Poland
| | - Michał Kabza
- Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland
| | | | - Robert Malinowski
- Institute of Plant Genetics, Polish Academy of Sciences, Poznan, Poland
| | - Rafal Ploski
- Department of Medical Genetics, Medical University of Warsaw, Warsaw, Poland
| | - Jan Matysiak
- Chair and Department of Inorganic and Analytical Chemistry, Poznan University of Medical Sciences, Poznan, Poland
| | - Marzena Gajecka
- Institute of Human Genetics, Polish Academy of Sciences, Poznan, Poland,Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland
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7
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Navneet S, Rohrer B. Elastin turnover in ocular diseases: A special focus on age-related macular degeneration. Exp Eye Res 2022; 222:109164. [PMID: 35798060 PMCID: PMC9795808 DOI: 10.1016/j.exer.2022.109164] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 06/08/2022] [Accepted: 06/20/2022] [Indexed: 12/30/2022]
Abstract
The extracellular matrix (ECM) and its turnover play a crucial role in the pathogenesis of several inflammatory diseases, including age-related macular degeneration (AMD). Elastin, a critical protein component of the ECM, not only provides structural and mechanical support to tissues, but also mediates several intracellular and extracellular molecular signaling pathways. Abnormal turnover of elastin has pathological implications. In the eye elastin is a major structural component of Bruch's membrane (BrM), a critical ECM structure separating the retinal pigment epithelium (RPE) from the choriocapillaris. Reduced integrity of macular BrM elastin, increased serum levels of elastin-derived peptides (EDPs), and elevated elastin antibodies have been reported in AMD. Existing reports suggest that elastases, the elastin-degrading enzymes secreted by RPE, infiltrating macrophages or neutrophils could be involved in BrM elastin degradation, thus contributing to AMD pathogenesis. EDPs derived from elastin degradation can increase inflammatory and angiogenic responses in tissues, and the elastin antibodies are shown to play roles in immune cell activity and complement activation. This review summarizes our current understanding on the elastases/elastin fragments-mediated mechanisms of AMD pathogenesis.
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Affiliation(s)
- Soumya Navneet
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA.
| | - Bärbel Rohrer
- Department of Ophthalmology, Medical University of South Carolina, Charleston, SC, USA; Department of Neurosciences, Medical University of South Carolina, Charleston, SC, USA; Ralph H. Johnson VA Medical Center, Division of Research, Charleston, SC, USA.
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8
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Zhao Z, Liang M, He H, Wang X, Zhu C, Li L, Liu B, Zong R, Jin Q, Wu H, Li W, Lin Z. Ovalbumin-Induced Allergic Inflammation Diminishes Cross-Linked Collagen Structures in an Experimental Rabbit Model of Corneal Cross-Linking. Front Med (Lausanne) 2022; 9:762730. [PMID: 35692541 PMCID: PMC9178108 DOI: 10.3389/fmed.2022.762730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 04/28/2022] [Indexed: 11/21/2022] Open
Abstract
Background Allergic conjunctivitis (AC) is one of the reported potential risk factors of progression in keratoconus patients after corneal cross-linking surgery; however, the causal relationship is still inconclusive. Recent studies have indicated that various inflammatory cytokines play a vital role in the development of primary keratoconus. It is still unclear whether these inflammatory mediators also trigger CXL failures. This study aimed to investigate the impact of AC on the rabbit corneas after trans-epithelial corneal cross-linking (TCXL). Methods A total of six rabbits were kept untreated as the normal control (NC) group. A total of 18 rabbits were treated by TCXL and divided into three groups (six in each group), namely, no treatment (TCXL group); induction of AC (TCXL + AC group); and induction of AC plus topical prednisolone acetate (TCXL + AC + PA group), according to additional treatment. AC was induced by topical application of ovalbumin after intraperitoneal pre-sensitization with ovalbumin. Rabbits were evaluated by slit lamp, in vivo laser scanning confocal microscopy, anterior segment optical coherence tomography, and measurement of corneal biomechanics. The cornea specimens were collected for the transmission electron microscope, the collagenase I digestion test, and PCR assay for TNF-α, IL-6, IL-1β, matrix metalloproteinase 9 (MMP-9), lysyl oxidase (LOX), and tissue inhibitor of metalloproteinases 1 (TIMP-1) on the day (D) 28. Results On D28, the TNF-α, IL-6, IL-1β, MMP-9, and LOX levels were significantly increased while the TIMP-1 was decreased in the TCXL + AC group when compared with the TCXL and TCXL + AC + PA groups. In vivo confocal microscopy revealed that at a depth of 150–210 μm, a trabecular patterned hyperdense structure surrounded by elongated needle-like processes could be observed in the TCXL and TCXL + AC + PA groups, but hardly seen in the TCXL + AC group. The demarcation lines were indistinct and blurred in the TCXL + AC group. An electron microscope demonstrated less interlacing fibril lamellae and higher interfibrillar spacing in the TCXL + AC group. The stability of corneal biomechanics and resistance to collagenase were decreased in the TCXL + AC group. Conclusion The corneal microstructures induced by TCXL and biomechanical stability were diminished in rabbits with AC but could be maintained by topical anti-inflammatory treatment. Our results supported the causal relationship between altered cytokine profiles and corneal microstructure after primary corneal cross-linking.
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Affiliation(s)
- Zhongyang Zhao
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Minghui Liang
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Huan He
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Xuemei Wang
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Chengfang Zhu
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Lan Li
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Bin Liu
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Rongrong Zong
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Qifang Jin
- The Second Affiliated Hospital of Nanchang University, Nanchang, China
| | - Huping Wu
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
- Fujian Key Laboratory of Ocular Surface and Corneal Disease, Affiliated Xiamen Eye Center of Xiamen University, Xiamen, China
- *Correspondence: Huping Wu,
| | - Wei Li
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
- Fujian Key Laboratory of Ocular Surface and Corneal Disease, Affiliated Xiamen Eye Center of Xiamen University, Xiamen, China
- Wei Li,
| | - Zhirong Lin
- Eye Institute and Affiliated Xiamen Eye Center of Xiamen University, School of Medicine, Xiamen University, Xiamen, China
- Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
- Fujian Key Laboratory of Ocular Surface and Corneal Disease, Affiliated Xiamen Eye Center of Xiamen University, Xiamen, China
- Zhirong Lin,
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Lalgudi VG, Shetty R, Nischal KK, Ziai S, Koaik M, Sethu S. Biochemical and molecular alterations and potential clinical applications of biomarkers in keratoconus. Saudi J Ophthalmol 2022; 36:7-16. [PMID: 35971485 PMCID: PMC9375466 DOI: 10.4103/sjopt.sjopt_203_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 12/05/2021] [Accepted: 02/19/2022] [Indexed: 11/06/2022] Open
Abstract
Keratoconus (KC) is a complex multifactorial corneal ectatic disorder, with disease onset commonly in the second-third decades significantly affecting quantity, quality of vision, and quality of life. Several pathways and factors such as eye rubbing, inflammatory, oxidative, metabolic, genetic, and hormonal among others have been studied in the last two decades. However, the management of KC is still based on a few "one-size fits all" approaches and is predominantly guided by topo/tomographic parameters. Consideration of the several novel factors which have the potential to be biomarkers in addressing several unanswered questions in the disease process could help in the better predictive ability of progression or vision loss and customization of treatment options. This article delves into the understanding of these novel factors or biomarkers based on the pathogenesis of KC and features a special focus on their potential clinical applications and their future role in personalized medicine.
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Affiliation(s)
- Vaitheeswaran G. Lalgudi
- Department of Cornea, External Disease and Refractive Surgery, University of Ottawa Eye Institute, The Ottawa Hospital, Ottawa, ON, Canada,Address for correspondence: Dr. Vaitheeswaran G. Lalgudi, Department of Cornea, External Disease and Refractive Surgery, University of Ottawa Eye Institute, The Ottawa Hospital, 501, Smyth Road, Ottawa, ON, Canada. E-mail:
| | - Rohit Shetty
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bengaluru, Karnataka, India
| | - Kanwal K. Nischal
- UPMC Eye Centre, UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA,Department of Pediatric Ophthalmology and Strabismus, UPMC Children's Hospital of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Setareh Ziai
- Department of Cornea, External Disease and Refractive Surgery, University of Ottawa Eye Institute, The Ottawa Hospital, Ottawa, ON, Canada,Department of Ophthalmology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Mona Koaik
- Department of Cornea, External Disease and Refractive Surgery, University of Ottawa Eye Institute, The Ottawa Hospital, Ottawa, ON, Canada,Department of Ophthalmology, Children's Hospital of Eastern Ontario, Ottawa, ON, Canada
| | - Swaminathan Sethu
- Molecular and Genetic Research, GROW Laboratories, Narayana Nethralaya Foundation, Bengaluru, Karnataka, India
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10
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Muench S, Roellig M, Balzani D. A new method for the in vivo identification of degenerated material property ranges of the human eye: feasibility analysis based on synthetic data. Biomech Model Mechanobiol 2022; 21:401-418. [PMID: 34928468 PMCID: PMC8940849 DOI: 10.1007/s10237-021-01541-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Accepted: 11/24/2021] [Indexed: 11/25/2022]
Abstract
This paper proposes a new method for in vivo and almost real-time identification of biomechanical properties of the human cornea based on non-contact tonometer data. Further goal is to demonstrate the method's functionality based on synthetic data serving as reference. For this purpose, a finite element model of the human eye is constructed to synthetically generate full-field displacements from different data sets with keratoconus-like degradations. Then, a new approach based on the equilibrium gap method combined with a mechanical morphing approach is proposed and used to identify the material parameters from virtual test data sets. In a further step, random absolute noise is added to the virtual test data to investigate the sensitivity of the new approach to noise. As a result, the proposed method shows a relevant accuracy in identifying material parameters based on full-field displacements. At the same time, the method turns out to work almost in real time (order of a few minutes on a regular workstation) and is thus much faster than inverse problems solved by typical forward approaches. On the other hand, the method shows a noticeable sensitivity to rather small noise amplitudes rendering the method not accurate enough for the precise identification of individual parameter values. However, analysis show that the accuracy is sufficient for the identification of property ranges which might be related to diseased tissues. Thereby, the proposed approach turns out promising with view to diagnostic purposes.
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Affiliation(s)
- Stefan Muench
- Department of Testing of Electronics and Optical Methods, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany
| | - Mike Roellig
- Department of Testing of Electronics and Optical Methods, Fraunhofer Institute for Ceramic Technologies and Systems IKTS, Dresden, Germany
| | - Daniel Balzani
- Chair of Continuum Mechanics, Ruhr University Bochum, Bochum, Germany.
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11
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Li H, Dong M, Zhou Q, Zhao L, Wang F, Wang X, Liu T, Xie L, Shi W. Corneal calcification of acellular porcine corneal stroma following lamellar keratoplasty. Acta Ophthalmol 2022; 100:164-174. [PMID: 33258298 DOI: 10.1111/aos.14665] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 09/20/2020] [Accepted: 10/12/2020] [Indexed: 11/28/2022]
Abstract
PURPOSE To describe the corneal calcification of acellular porcine corneal stroma (APCS) following lamellar keratoplasty (LKP) and identify risk factors. METHODS Two cases of APCS calcification were evaluated by slit-lamp photography and anterior segment optical coherence tomography (AS-OCT). von Kossa staining and scanning electron microscope/energy-dispersive spectrometry (SEM/EDS) were performed on pathologic tissue. Associated graft and postoperative risk factors were analysed. Acellular porcine corneal stroma (APCS) cleanliness and element content after rinsing with sterilized water were observed by SEM/EDS and inductively coupled plasma mass spectrometry. Calcium metabolism-related proteins were analysed by protein mass spectrometry. Corneal epithelial defects and postoperative medications were reviewed. RESULTS Two cases of APCS calcification occurred at 23 and 22 days postoperatively. Anterior segment optical coherence tomography (AS-OCT) and von Kossa staining demonstrated calcium deposition in the superficial stroma composed of calcium, phosphorus and oxygen conforming to the Ca/P ratio of hydroxyapatite. Phosphate crystals were present on the APCS surface and decreased with number of rinsing times. The phosphorus content of APCS was minimal after rinsing 10 times and avoiding excessive corneal swelling. Calcium metabolism-related proteins were downregulated in APCS. Patients with corneal calcification had 1-week postoperative corneal epithelial defects and were treated with three types of phosphorous eyedrops. CONCLUSIONS Acellular porcine corneal stroma (APCS) calcification occurs in the superficial corneal stroma about 1 month after LKP. The application of AS-OCT, von Kossa staining and SEM/EDS provides a basis for the clinical and pathological diagnosis of corneal calcification. The associated risk factors were mainly high phosphorus content and downregulated calcium metabolism-related proteins in APCS. Postoperative epithelial defects, inflammation and use of phosphorous eyedrops may promote corneal calcification.
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Affiliation(s)
- Hua Li
- Department of Ophthalmology Clinical Medical College of Shandong University Jinan China
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
| | - Muchen Dong
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Eye Hospital of Shandong First Medical University Jinan China
| | - Qingjun Zhou
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Qingdao Eye Hospital of Shandong First Medical University Qingdao China
| | - Long Zhao
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
| | - Fuyan Wang
- Department of Ophthalmology Clinical Medical College of Shandong University Jinan China
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
| | - Xin Wang
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Eye Hospital of Shandong First Medical University Jinan China
| | - Ting Liu
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Qingdao Eye Hospital of Shandong First Medical University Qingdao China
| | - Lixin Xie
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Qingdao Eye Hospital of Shandong First Medical University Qingdao China
| | - Weiyun Shi
- State Key Laboratory Cultivation Base Shandong Provincial Key Laboratory of Ophthalmology Shandong Eye Institute Shandong First Medical University & Shandong Academy of Medical Sciences Qingdao China
- Eye Hospital of Shandong First Medical University Jinan China
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12
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Gupta S, Buyank F, Sinha NR, Grant DG, Sinha PR, Iozzo RV, Chaurasia SS, Mohan RR. Decorin regulates collagen fibrillogenesis during corneal wound healing in mouse in vivo. Exp Eye Res 2022; 216:108933. [PMID: 35031282 PMCID: PMC8885890 DOI: 10.1016/j.exer.2022.108933] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/14/2021] [Accepted: 01/05/2022] [Indexed: 12/22/2022]
Abstract
A characteristic rigid spatial arrangement of collagen fibrils in the stroma is critical for corneal transparency. This unique organization of collagen fibrils in corneal stroma can be impacted by the presence and interactions of proteoglycans and extracellular matrix (ECM) proteins in a corneal microenvironment. Earlier studies revealed that decorin, a leucine-rich proteoglycan in stroma, regulates keratocyte-collagen matrix assembly and wound healing in the cornea. This study investigated the role of decorin in the regulation of stromal fibrillogenesis and corneal transparency in vivo employing a loss-of-function genetic approach using decorin null (dcn-/-) and wild type (dcn+/+) mice and a standard alkali-injury model. A time-dependent ocular examinations with Slit lamp microscope in live animals assessed corneal clarity, haze, and neovascularization levels in normal and injured eyes. Morphometric changes in normal and injured dcn+/+ and dcn-/- corneas, post-euthanasia, were analyzed with Masson's Trichrome and Periodic Acid-Schiff (PAS) histology evaluations. The ultrastructure changes in all corneas were investigated with transmission electron microscopy (TEM). Injury to eye produced clinically relevant corneal haze and neovascularization in dcn-/- and dcn+/+ mice while corneas of uninjured eyes remained clear and avascular. A clinically significant haze and neovascularization appeared in injured dcn-/- corneas compared to the dcn+/+ corneas at day 21 post-injury and not at early tested times. Histological examinations revealed noticeably abnormal morphology and compromised collagen levels in injured dcn-/- corneas compared to the injured/normal dcn+/+ and uninjured dcn-/- corneas. TEM analysis exhibited remarkably uneven collagen fibrils size and distribution in the stroma with asymmetrical organization and loose packing in injured dcn-/- corneas than injured/normal dcn+/+ and uninjured dcn-/- corneas. The minimum and maximum inter-fibril distances were markedly irregular in injured dcn-/- corneas compared to all other corneas. Together, results of clinical, histological, and ultrastructural investigations in a genetic knockout model suggested that decorin influenced stromal fibrillogenesis and transparency in healing cornea.
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Affiliation(s)
- Suneel Gupta
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri, USA.,Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Filiz Buyank
- Department of Computer Science, University of Missouri, Columbia, Missouri, USA
| | - Nihant R. Sinha
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri, USA.,Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - DeAna G. Grant
- Electron Microscopy Core, University of Missouri, Columbia, Missouri, USA
| | - Prashant R. Sinha
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri, USA.,Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Renato V. Iozzo
- Department of Pathology, Anatomy, and Cell Biology, and Translational Cellular Oncology Program, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Shyam S. Chaurasia
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri, USA.,Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA
| | - Rajiv R. Mohan
- Harry S. Truman Memorial Veterans’ Hospital, Columbia, Missouri, USA.,Departments of Veterinary Medicine & Surgery and Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, Missouri, USA.,Mason Eye Institute, School of Medicine, University of Missouri, Columbia, Missouri, USA.,Corresponding author: Rajiv R. Mohan, MS, PhD, FARVO, Professor of Ophthalmology & Molecular Medicine, University of Missouri, 1600 E. Rollins Rd, Columbia, MO 65211,
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13
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Abihaidar N, Garcin T. Traumatic Descemet's membrane detachment in an old penetrating keratoplasty graft for keratoconus. J Fr Ophtalmol 2022; 45:e277-e279. [DOI: 10.1016/j.jfo.2021.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2021] [Accepted: 09/08/2021] [Indexed: 11/25/2022]
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14
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The Role of the Stromal Extracellular Matrix in the Development of Pterygium Pathology: An Update. J Clin Med 2021; 10:jcm10245930. [PMID: 34945227 PMCID: PMC8707182 DOI: 10.3390/jcm10245930] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/13/2021] [Accepted: 12/15/2021] [Indexed: 12/31/2022] Open
Abstract
Pterygium is a benign fibrovascular lesion of the bulbar conjunctiva with frequent involvement of the corneal limbus. Its pathogenesis has been mainly attributed to sun exposure to ultraviolet-B radiation. Obtained evidence has shown that it is a complex and multifactorial process which involves multiple mechanisms such as oxidative stress, dysregulation of cell cycle checkpoints, induction of inflammatory mediators and growth factors, angiogenic stimulation, extracellular matrix (ECM) disorders, and, most likely, viruses and hereditary changes. In this review, we aim to collect all authors’ experiences and our own, with respect to the study of fibroelastic ECM of pterygium. Collagen and elastin are intrinsic indicators of physiological and pathological states. Here, we focus on an in-depth analysis of collagen (types I and III), as well as the main constituents of elastic fibers (tropoelastin (TE), fibrillins (FBNs), and fibulins (FBLNs)) and the enzymes (lysyl oxidases (LOXs)) that carry out their assembly or crosslinking. All the studies established that changes in the fibroelastic ECM occur in pterygium, based on the following facts: An increase in the synthesis and deposition of an immature form of collagen type III, which showed the process of tissue remodeling. An increase in protein levels in most of the constituents necessary for the development of elastic fibers, except FBLN4, whose biological roles are critical in the binding of the enzyme LOX, as well as FBN1 for the development of stable elastin. There was gene overexpression of TE, FBN1, FBLN5, and LOXL1, while the expression of LOX and FBLN2 and -4 remained stable. In conclusion, collagen and elastin, as well as several constituents involved in elastic fiber assembly are overexpressed in human pterygium, thus, supporting the hypothesis that there is dysregulation in the synthesis and crosslinking of the fibroelastic component, constituting an important pathogenetic mechanism for the development of the disease.
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15
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Alenezi B, Kazaili A, Akhtar R, Radhakrishnan H. Corneal biomechanical properties following corneal cross-linking: Does age have an effect? Exp Eye Res 2021; 214:108839. [PMID: 34785203 DOI: 10.1016/j.exer.2021.108839] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 10/28/2021] [Accepted: 11/09/2021] [Indexed: 12/21/2022]
Abstract
PURPOSE To explore the effect of age on corneal biomechanical properties following corneal cross-linking (CXL). METHODS A total of 12 pairs of human eye-banked corneas (24 corneas, from 14 females and 10 males) were used in the study. The mean donor age was 48.5 years (ranging from 26 to 71 years). Corneas were divided into three age groups: A (26-41 years), B (42-57 years) and C (58-71 years), with four pairs in each group. For each pair, the right corneas were cross-linked using accelerated CXL with UVA (10 mW/cm2) and riboflavin, while the left corneas served as controls and were not exposed to either UVA irradiation or riboflavin. The corneal elastic modulus of the anterior, mid and posterior corneal stroma was measured using nanoindentation. RESULTS The difference in the corneal elastic modulus following CXL was significant in the anterior (p = 0.00002) and mid stroma (p = 0.001); however, the difference was not significant in the posterior stroma (p = 0.27) when compared to control corneas. The corneal elastic modulus of the anterior stroma increased by 178.44% in Group A, 119.7% in Group B and 50.73% in Group C compared to control corneas. For the mid stroma, the elastic modulus increased by 47.35% in Group A, 25% in Group B and 24.56% in Group C. No differences were observed in the posterior stroma between age groups. CONCLUSIONS Corneal elasticity showed a greater response to CXL in the younger group compared to older groups. CXL treatment showed effectiveness in enhancing stromal strength, and the effect was concentrated in the anterior and mid stroma with minimal impact on the posterior stroma in all age groups.
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Affiliation(s)
- Bandar Alenezi
- School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK; College of Applied Medical Sciences, Qassim University, Buraidah, Qassim, Saudi Arabia.
| | - Ahmed Kazaili
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, UK; Department of Biomedical Engineering, College of Engineering, University of Babylon, Hillah, Iraq
| | - Riaz Akhtar
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, UK
| | - Hema Radhakrishnan
- School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
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16
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D'Souza S, Nair AP, Sahu GR, Vaidya T, Shetty R, Khamar P, Mullick R, Gupta S, Dickman MM, Nuijts RMMA, Mohan RR, Ghosh A, Sethu S. Keratoconus patients exhibit a distinct ocular surface immune cell and inflammatory profile. Sci Rep 2021; 11:20891. [PMID: 34686755 PMCID: PMC8536707 DOI: 10.1038/s41598-021-99805-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/23/2021] [Indexed: 02/06/2023] Open
Abstract
Inflammatory factors have been considered to contribute to keratoconus (KC) pathogenesis. This study aims to determine the immune cells subsets and soluble inflammatory factor profile on the ocular surface of KC patients. 32 KC subjects (51 eyes) across different grades of severity and 15 healthy controls (23 eyes) were included in the study. Keratometry and pachymetry measurements were recorded. Ocular surface immune cells (collected by ocular surface wash) immunophenotyped using flow cytometry include leukocytes, neutrophils, macrophages, natural killer (NK) cells, pan-T cells, gamma delta T (γδT) cells and NKT cells. Tear fluid collected using Schirmer's strip was used to measure 50 soluble factors by multiplex ELISA. Proportions of activated neutrophils, NK cells and γδT cells were significantly increased in KC patients. Significantly higher levels of tear fluid IL-1β, IL-6, LIF, IL-17A, TNFα, IFNα/β/γ, EPO, TGFβ1, PDGF-BB, sVCAM, sL-selectin, granzyme-B, perforin, MMP2, sFasL and IgE, along with significantly lower levels of IL-1α and IL-9 were observed in KC patients. Alterations observed in few of the immuno-inflammatory parameters correlated with grades of disease, allergy, eye rubbing and keratometry or pachymetry measurements. The observation implies a distinct immuno-inflammatory component in KC pathogenesis and its potential as an additional therapeutic target in KC management.
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Affiliation(s)
- Sharon D'Souza
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Archana Padmanabhan Nair
- GROW Research Laboratory, Narayana Nethralaya Foundation, 3rd Floor, Narayana Nethralaya, #258/A Hosur Road, Bommasandra, Bangalore, 560099, India.,Manipal Academy of Higher Education, Manipal, India
| | - Ganesh Ram Sahu
- GROW Research Laboratory, Narayana Nethralaya Foundation, 3rd Floor, Narayana Nethralaya, #258/A Hosur Road, Bommasandra, Bangalore, 560099, India
| | - Tanuja Vaidya
- GROW Research Laboratory, Narayana Nethralaya Foundation, 3rd Floor, Narayana Nethralaya, #258/A Hosur Road, Bommasandra, Bangalore, 560099, India.,Manipal Academy of Higher Education, Manipal, India
| | - Rohit Shetty
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Pooja Khamar
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Ritika Mullick
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Sneha Gupta
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Mor M Dickman
- University Eye Clinic Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands.,MERLN Institute for Technology-Inspired Regenerative Medicine, Maastricht University, Maastricht, The Netherlands
| | - Rudy M M A Nuijts
- University Eye Clinic Maastricht, Maastricht University Medical Center, Maastricht, The Netherlands
| | - Rajiv R Mohan
- Department of Veterinary Medicine and Surgery, University of Missouri, 1600 E. Rollins Rd, Columbia, MO, 65211, USA. .,Mason Eye Institute, School of Medicine, University of Missouri, Columbia, MO, USA. .,Harry S Truman Veterans' Memorial Hospital, Columbia, MO, USA.
| | - Arkasubhra Ghosh
- GROW Research Laboratory, Narayana Nethralaya Foundation, 3rd Floor, Narayana Nethralaya, #258/A Hosur Road, Bommasandra, Bangalore, 560099, India. .,Singapore Eye Research Institute, Singapore, Singapore.
| | - Swaminathan Sethu
- GROW Research Laboratory, Narayana Nethralaya Foundation, 3rd Floor, Narayana Nethralaya, #258/A Hosur Road, Bommasandra, Bangalore, 560099, India.
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17
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Lewis PN, Young RD, Souza RB, Quantock AJ, Meek KM. Contrast-Enhanced Tissue Processing of Fibrillin-Rich Elastic Fibres for 3D Visualization by Volume Scanning Electron Microscopy. Methods Protoc 2021; 4:mps4030056. [PMID: 34449675 PMCID: PMC8395850 DOI: 10.3390/mps4030056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/04/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022] Open
Abstract
Elastic fibres constitute an important component of the extracellular matrix and currently are the subject of intensive study in order to elucidate their assembly, function and involvement in cell-matrix interactions and disease. However, few studies to date have investigated the 3D architecture of the elastic fibre system in bulk tissue. We describe a protocol for preparation of tissue samples, including primary fixation and backscatter electron contrast-enhancement steps, through dehydration into stable resin-embedded blocks for volume electron microscopy. The use of low molecular weight tannic acid and alcoholic lead staining are critical stages in this procedure. Block preparation by ultramicrotomy and evaporative metal coating prior to microscopical examination are also described. We present images acquired from serial block face scanning electron microscopy of cornea and aorta showing target structures clearly differentiated from cells and other matrix components. The processing method imparts high contrast to fibrillin-containing elastic fibres, thus facilitating their segmentation and rendering into 3D reconstructions by image analysis software from large serial image datasets.
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Affiliation(s)
- Philip N. Lewis
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
- Correspondence:
| | - Robert D. Young
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
| | - R. B. Souza
- Department of Genetics and Evolutionary Biology, University of São Paulo, Rua de Matão 05508-090, Brazil;
| | - Andrew J. Quantock
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
| | - Keith M. Meek
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, Cardiff CF24 4HQ, UK; (R.D.Y.); (A.J.Q.); (K.M.M.)
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18
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Bagheri NM, Kadkhodaei M, Pirhadi S, Mosaddegh P. Effects of intracorneal ring segments implementation technique and design on corneal biomechanics and keratometry in a personalized computational analysis. Sci Rep 2021; 11:14433. [PMID: 34257343 PMCID: PMC8277910 DOI: 10.1038/s41598-021-93821-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 06/30/2021] [Indexed: 11/08/2022] Open
Abstract
The implementation of intracorneal ring segments (ICRS) is one of the successfully applied refractive operations for the treatment of keratoconus (kc) progression. The different selection of ICRS types along with the surgical implementation techniques can significantly affect surgical outcomes. Thus, this study aimed to investigate the influence of ICRS implementation techniques and design on the postoperative biomechanical state and keratometry results. The clinical data of three patients with different stages and patterns of keratoconus were assessed to develop a three-dimensional (3D) patient-specific finite-element model (FEM) of the keratoconic cornea. For each patient, the exact surgery procedure definitions were interpreted in the step-by-step FEM. Then, seven surgical scenarios, including different ICRS designs (complete and incomplete segment), with two surgical implementation methods (tunnel incision and lamellar pocket cut), were simulated. The pre- and postoperative predicted results of FEM were validated with the corresponding clinical data. For the pre- and postoperative results, the average error of 0.4% and 3.7% for the mean keratometry value ([Formula: see text]) were predicted. Furthermore, the difference in induced flattening effects was negligible for three ICRS types (KeraRing segment with arc-length of 355, 320, and two separate 160) of equal thickness. In contrast, the single and double progressive thickness of KeraRing 160 caused a significantly lower flattening effect compared to the same type with constant thickness. The observations indicated that the greater the segment thickness and arc-length, the lower the induced mean keratometry values. While the application of the tunnel incision method resulted in a lower [Formula: see text] value for moderate and advanced KC, the induced maximum Von Mises stress on the postoperative cornea exceeded the induced maximum stress on the cornea more than two to five times compared to the pocket incision and the preoperative state of the cornea. In particular, an asymmetric regional Von Mises stress on the corneal surface was generated with a progressive ICRS thickness. These findings could be an early biomechanical sign for a later corneal instability and ICRS migration. The developed methodology provided a platform to personalize ICRS refractive surgery with regard to the patient's keratoconus stage in order to facilitate the efficiency and biomechanical stability of the surgery.
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Affiliation(s)
- Niksa Mohammadi Bagheri
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Mahmoud Kadkhodaei
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran
| | - Shiva Pirhadi
- Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, 14778-93855, Iran
| | - Peiman Mosaddegh
- Department of Mechanical Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran.
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19
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Wilson A, Marshall J. A review of corneal biomechanics: Mechanisms for measurement and the implications for refractive surgery. Indian J Ophthalmol 2021; 68:2679-2690. [PMID: 33229643 PMCID: PMC7856929 DOI: 10.4103/ijo.ijo_2146_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Detailed clinical assessment of corneal biomechanics has the potential to revolutionize the ophthalmic industry through enabling quicker and more proficient diagnosis of corneal disease, safer and more effective surgical treatments, and the provision of customized and optimized care. Despite these wide-ranging benefits, and an outstanding clinical need, the provision of technology capable of the assessment of corneal biomechanics in the clinic is still in its infancy. While laboratory-based technologies have progressed significantly over the past decade, there remain significant gaps in our knowledge regarding corneal biomechanics and how they relate to shape and function, and how they change in disease and after surgical intervention. Here, we discuss the importance, relevance, and challenges associated with the assessment of corneal biomechanics and review the techniques currently available and underdevelopment in both the laboratory and the clinic.
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Affiliation(s)
- Abby Wilson
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
| | - John Marshall
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
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20
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Goweida MB, Abuelkheir A, El-Menawy WAR, Mahmoud S. Dynamics of Big Bubble Formation During Deep Anterior Lamellar Keratoplasty in Eyes with Advanced Keratoconus. Clin Ophthalmol 2020; 14:4305-4310. [PMID: 33324036 PMCID: PMC7733416 DOI: 10.2147/opth.s277738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/19/2020] [Indexed: 11/23/2022] Open
Abstract
Purpose To study the dynamics of big bubble (BB) formation in eyes with advanced keratoconus (KC) during deep anterior lamellar keratoplasty (DALK). Methods A retrospective review of medical records and videos of DALK surgeries performed during the period from January 2013 to December 2019 on keratoconic eyes. Eyes with formed BB, in the presence of a relatively clear stroma, were included. We studied the following parameters the location of BB commencement, duration from the start of the bubble until complete formation, and the pattern of air passage during the formation process. Results A total of 37 eyes met the inclusion criteria. Type 1 BB was formed in 22 eyes with a mean formation time of 1.9 ± 1.1 seconds and a mean bubble diameter of 7.6 ± 1.1 mm. Type 1 BB started in the center as a small dome expanding centrifugally with preceding localized stromal whitening in 19 eyes and without whitening in three eyes. Type 2 BB was formed in 14 eyes with a mean formation time of 0.3 ± 0.12 seconds and a mean bubble diameter of 7.4 ± 1.8 mm. Type 2 BB started in the center in 13 eyes and the mid periphery in one eye, through either direct access to the plane between Descemet’s membrane and the pre-Descemet’s layer in six eyes, or preceded by a small intrastromal bubble in eight eyes. Mixed bubble was observed in one eye, which started as a small central Type 1 BB followed by the rapid formation of a Type 2 BB. Conclusion Eyes with KC are associated with central commencements of both Type 1 and Type 2 BB during DALK. Duration of BB formation was significantly faster in Type 2 BB, with most starting as a small intrastromal bubble before air gain access to the plane between DM and stroma.
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Affiliation(s)
- Mohamed Bahgat Goweida
- Department of Ophthalmology, Alexandria Main, University Hospital, Alexandria, Egypt.,Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Amr Abuelkheir
- Department of Ophthalmology, Alexandria Main, University Hospital, Alexandria, Egypt.,Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Wael Abdel Rahman El-Menawy
- Department of Ophthalmology, Alexandria Main, University Hospital, Alexandria, Egypt.,Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Shahira Mahmoud
- Department of Ophthalmology, Alexandria Main, University Hospital, Alexandria, Egypt.,Faculty of Medicine, Alexandria University, Alexandria, Egypt
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21
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Shetty R, D'Souza S, Khamar P, Ghosh A, Nuijts RMMA, Sethu S. Biochemical Markers and Alterations in Keratoconus. Asia Pac J Ophthalmol (Phila) 2020; 9:533-540. [PMID: 33323707 DOI: 10.1097/apo.0000000000000332] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Keratoconus (KC) is a corneal ectatic condition characterized by focal structural changes, resulting in progressive thinning, biomechanical weakening, and steeping of the cornea that can lead to worsening visual acuity due to irregular astigmatism and corneal scarring in more advanced cases. It is a relatively common ectatic disease of the cornea predominantly affecting the younger population. Despite its worldwide prevalence, its incidence is rather varied with a higher incidence among the Middle Eastern and South Asian population. Dysregulated corneal extracellular matrix remodeling underlies KC pathogenesis. However, a lack of absolute clarity regarding the factors that initiate and drive progression poses a significant challenge in its prevention and management. KC is a complex multifactorial disease as it is associated with a wide variety of etiological factors such as environmental stimuli/insults, oxidative stress, genetic predisposition, comorbidities, and eye rubbing. A series of studies using corneal tissues (epithelium, stroma), cultured corneal fibroblasts/keratocytes, tear fluid, aqueous humor, and blood from KC subjects has reported significant alterations in various biochemical factors such as extracellular matrix components, cellular homeostasis regulators, inflammatory factors, hormones, metabolic products, and chemical elements. It has become apparent that alterations in the biochemical mediators (related to various etiologies) could contribute to KC pathogenesis by altering the dynamics of extracellular matrix remodeling events such as collagen deposition, degradation, and cross-linking in the cornea. Determining key disease contributing biochemical mediators would aid in disease monitoring, prediction or abatement of disease progression, and development of targeted therapeutics to improve disease prognosis.
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Affiliation(s)
- Rohit Shetty
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Sharon D'Souza
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Pooja Khamar
- Department of Cornea and Refractive Surgery, Narayana Nethralaya, Bangalore, India
| | - Arkasubhra Ghosh
- GROW Research Lab, Narayana Nethralaya Foundation, Bangalore, India
| | - Rudy M M A Nuijts
- University Eye Clinic Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
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22
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Regenerative and Antioxidant Properties of Autologous Platelet-Rich Plasma Can Reserve the Aging Process of the Cornea in the Rat Model. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:4127959. [PMID: 33299525 PMCID: PMC7704147 DOI: 10.1155/2020/4127959] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 09/14/2020] [Accepted: 11/07/2020] [Indexed: 12/19/2022]
Abstract
Aging is a natural progressive decline in the biological function of cells. Age-related changes in the cornea can affect its ability to refract light or repair itself. Platelet-rich plasma (PRP) has a promising role in regenerative medicine and evidenced its efficacy in multiple fields, but in corneal aging has not yet been elucidated. The present work was performed to estimate the regenerative antioxidant effect of PRP on corneal aging in rats. Rats were assigned into two main groups: (GI) adult group and (GII) aged group. The adult group was divided into GIa (adult rats), GIb (adult-saline treated), and GIc (adult-PRP treated). The aged group was divided into GIIa (aged rats) and GIIb (aged, PRP treated). PRP was administered by a single subconjunctival injection. After 10 days, histological, ultrastructural, immunohistochemical, and morphometrical investigations were carried out. Examination of the corneal sections of the aged group revealed corneal epithelial thinning, shedding of the surface epithelium with loss of desmosomal junction, and irregularity in Bowman's membrane. Disorganized widely spaced collagen bundles and neovascularization were detected in corneal stroma associated with thickening in Descemet's membrane. Ultrastructural examination revealed shrunken hyperchromatic nuclei, swollen mitochondria, and scanty cytoplasm with a strong nuclear reaction for caspase-3 immunostaining. Moreover, antioxidant/free radicals' imbalance was detected by the increase of malondialdehyde (MDA) level with a decrease of glutathione peroxidase (GPx) and superoxide dismutase (SOD) levels. In contrast, GIIb (aged, PRP treated) section examination revealed a restoration of the thickness of the corneal epithelial layer and Descemet's membrane with an amendment of collagen fiber regularity that is associated with weak nuclear reaction to caspase-3 and recovery of the balance in the redox state. These findings proved the effectiveness of PRP as a promising regenerative treatment for the age-associated changes in the cornea.
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Wilson A, Jones J, Tyrer JR, Marshall J. An interferometric ex vivo study of corneal biomechanics under physiologically representative loading, highlighting the role of the limbus in pressure compensation. EYE AND VISION 2020; 7:43. [PMID: 32832574 PMCID: PMC7433364 DOI: 10.1186/s40662-020-00207-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 07/25/2020] [Indexed: 12/23/2022]
Abstract
Background The mechanical properties of the cornea are complex and regionally variable. This paper uses an original method to investigate the biomechanics of the cornea in response to hydrostatic loading over the typical physiological range of intra-ocular pressure (IOP) fluctuations thereby increasing understanding of clinically relevant corneal biomechanical properties and their contributions to the refractive properties of the cornea. Methods Displacement speckle pattern interferometry (DSPI) was used to measure the total surface displacement of 40 porcine and 6 human corneal-scleral specimens in response to pressure variations up to 1 mmHg from a baseline of 16.5 mmHg. All specimens were mounted in a modified artificial anterior chamber (AAC) and loaded hydrostatically. Areas of high strain in response to loading were identified by comparing the displacements across different regions. Results The nature of the response of the corneal surface to loading demonstrated high regional topographic variation. Mechanical properties were shown to be asymmetrical, and deformation of the limbal and pre-limbal regions dominated these responses respectively with over 90% (N-T) and 60% (S-I) of the total maximum displacement occurring in these regions indicating high-strain. In contrast, the curvature of the central cornea remained relatively unchanged merely translating in position. Conclusions The limbal and pre-limbal regions of the cornea appear to be fundamental to the absorption of small pressure fluctuations facilitating the curvature of the central cornea to remain relatively unchanged. The differential mechanical properties of this region could have important implications for the application of corneal surgery and corneal crosslinking, warranting further investigation.
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Affiliation(s)
- Abby Wilson
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK
| | - John Jones
- Laser Optical Engineering Ltd., Derbyshire, UK
| | - John R Tyrer
- Wolfson School of Mechanical, Manufacturing and Electrical Engineering, Loughborough University, Loughborough, UK.,Laser Optical Engineering Ltd., Derbyshire, UK
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24
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Feneck EM, Lewis PN, Meek KM. Identification of a Primary Stroma and Novel Endothelial Cell Projections in the Developing Human Cornea. Invest Ophthalmol Vis Sci 2020; 61:5. [PMID: 32492106 PMCID: PMC7415898 DOI: 10.1167/iovs.61.6.5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 01/06/2020] [Indexed: 12/20/2022] Open
Abstract
Purpose To investigate the initial events in the development of the human cornea, focusing on cell migration, and extracellular matrix synthesis and organization. To determine whether elastic fibers are present in the extracellular matrix during early human corneal development. Methods Human corneas were collected from week 7 to week 17 of development. An elastic fiber-enhancing stain, tannic acid-uranyl acetate, was applied to all tissue. Three-dimensional serial block-face scanning electron microscopy combined with conventional transmission electron microscopy was used to analyze the corneal stroma. Results An acellular collagenous primary stroma with an orthogonal arrangement of fibrils was identified in the central cornea from week 7 of corneal development. At week 7.5, mesenchymal cells migrated toward the central cornea and associated with the acellular collagenous matrix. Novel cell extensions from the endothelium were identified. Elastic fibers were found concentrated in the posterior peripheral corneal stroma from week 12 of corneal development. Conclusions This study provides novel evidence of an acellular primary stroma in the early development of the embryonic human cornea. Cell extensions exist as part of a communication system and are hypothesized to assist in the migration of the mesenchymal cells and the development of the mature cornea. Elastic fibers identified in early corneal development may play an important role in establishing corneal shape.
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Affiliation(s)
- Eleanor M. Feneck
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Philip N. Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Keith M. Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
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25
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De Stefano VS, Ford MR, Seven I, Dupps WJ. Depth-Dependent Corneal Biomechanical Properties in Normal and Keratoconic Subjects by Optical Coherence Elastography. Transl Vis Sci Technol 2020; 9:4. [PMID: 32832211 PMCID: PMC7414661 DOI: 10.1167/tvst.9.7.4] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 04/07/2020] [Indexed: 12/15/2022] Open
Abstract
Purpose Compare depth-resolved biomechanical properties in normal and keratoconic corneas in live human subjects using optical coherence elastography (OCE). Methods In a prospective series of normal and keratoconus (KC) eyes, a corneal perturbation was applied by a custom swept-source OCE system using a transparent flat lens coupled to force transducers. Cross-correlation was applied to track frame-by-frame OCT speckle displacement. Regional displacements for the anterior and posterior stroma were plotted in force versus displacement (k) graphs. A spatial biomechanical property ratio (ka/kp ) was defined by dividing the maximum total displacement by the maximum force for the anterior (ka ) and posterior cornea (kp) and was compared between normal and KC groups with the Mann-Whitney U test. Area under the receiver operating characteristics curve (AUROC) for differentiating normal and KC eyes was calculated for ka/kp , kmax, and thinnest point of corneal thickness (TPCT). Results Thirty-six eyes were analyzed (21 eyes of 12 normal subjects and 15 KC eyes of 12 subjects). The ka/kp for the normal group was 1.135 ± 0.07 (mean ± standard deviation) and 1.02 ± 0.08 for the KC group (P < 0.001), indicating a relative deficit in anterior stromal stiffness in KC eyes. AUROC was 0.91 for ka /kp , 0.95 for kmax, and 1 for TPCT. Conclusions Significant differences in depth-dependent corneal biomechanical properties were observed between normal and KC subjects. Translational Relevance OCE was applied for the first time to human KC subjects and revealed alterations in the normal anterior-to-posterior stromal stiffness gradient, a novel and clinically accessible disease biomarker.
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Affiliation(s)
- Vinicius S De Stefano
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Ophthalmology and Visual Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Matthew R Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Ibrahim Seven
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - William J Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, USA
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26
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27
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Birbal RS, Parker JS, van Dijk K, Oellerich S, Dapena I, Melles GRJ. Hydrops after corneal perforation during manual deep anterior lamellar keratoplasty for keratoconus. Acta Ophthalmol 2020; 98:e522-e523. [PMID: 31773875 DOI: 10.1111/aos.14320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Rénuka S Birbal
- Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, The Netherlands.,Melles Cornea Clinic, Rotterdam, The Netherlands.,Amnitrans EyeBank Rotterdam, Rotterdam, The Netherlands
| | - Jack S Parker
- NIIOS-USA, California, USA.,Parker Cornea, Birmingham, Alabama, USA
| | - Korine van Dijk
- Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, The Netherlands.,Melles Cornea Clinic, Rotterdam, The Netherlands
| | - Silke Oellerich
- Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, The Netherlands
| | - Isabel Dapena
- Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, The Netherlands.,Melles Cornea Clinic, Rotterdam, The Netherlands
| | - Gerrit R J Melles
- Netherlands Institute for Innovative Ocular Surgery (NIIOS), Rotterdam, The Netherlands.,Melles Cornea Clinic, Rotterdam, The Netherlands.,Amnitrans EyeBank Rotterdam, Rotterdam, The Netherlands.,NIIOS-USA, California, USA
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28
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Ross AR, Said DG, Colabelli Gisoldi RAM, Nubile M, El-Amin A, Gabr AF, Abd Ed-Moniem M, Mencucci R, Pocobelli A, Mastropasqua L, Dua HS. Optimizing pre-Descemet endothelial keratoplasty technique. J Cataract Refract Surg 2020; 46:667-674. [PMID: 32358258 DOI: 10.1097/j.jcrs.0000000000000157] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Pre-Descemet endothelial keratoplasty (PDEK) is an alternative technique to Descemet membrane endothelial keratoplasty (DMEK). The preparation of PDEK tissue by pneumatic dissection is simple and reproducible. The PDEK clamp helps to consistently obtain a type 1 big bubble. The mean size of type 1 big bubble is 7.255 ± 0.535 × 6.745 ± 0.668 mm. The volume of air required to obtain type 1 big bubble is 0.14 to 0.37 mL. Dissection of PDEK tissue can be achieved by trephination or manual excision. Insertion of tissue into the recipient eye can be by injection or pulling. Unfolding techniques used for PDEK are similar to those used in DMEK. Unlike DMEK, PDEK tissue is easier to handle and unscroll and allows use of younger donors. It could help surgeons converting to endothelial keratoplasty, with significant advantages in preparation, handling, and unscrolling in the eye.
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Affiliation(s)
- Andrew R Ross
- From the Department of Ophthalmology, Nottingham University Hospitals NHS Trust and Section of Academic Ophthalmology, Division of Clinical Neuroscience, University of Nottingham (Ross, Said, Dua), Nottingham, United Kingdom; Department of Ophthalmology, Aswan University (Ross, El-Amin, Gabr, Moniem), Aswan, Egypt; Hospital San Giovanni Addolorata (Colabelli Gisoldi, Pocobelli), Rome, Department of Medicine and Science of Ageing, Ophthalmic Clinic, National High Technology Eye Center, G. d'Annunzio University of Chieti (Nubile, Mastropasqua), Pescara, Department of Oto-Neuro-Ophthalmological Surgical Sciences, Eye Clinic, University of Florence (Mencucci), Florence, Italy
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29
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Jin M, Wang Y, Wang Y, Li Y, Wang G, Liu X, Xue Y, Liu Z, Li C. Protective Effects Oncorneal Endothelium During Intracameral Irrigation Using N-(2)-l-alanyl-l-Glutamine. Front Pharmacol 2020; 11:369. [PMID: 32292346 PMCID: PMC7118711 DOI: 10.3389/fphar.2020.00369] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Accepted: 03/10/2020] [Indexed: 12/21/2022] Open
Abstract
Corneal endothelial disease is a global sight-threatening disease, and corneal transplantation using donor corneas remains the sole therapeutic option. A previous work demonstrated that N (2)-alanyl-glutamine (Ala-Gln) protected against apoptosis and cellular stress, and maintained intestinal tissue integrity. In this pursuit, the present study aimed to examine the effect of Ala-Gln in the protection of the corneal endothelium and expand its range of potential clinical applications. Mice in the control group were intracamerally irrigated with Ringers lactate injection, whereas those in the experimental group were irrigated with Ringers lactate injection containing Ala-Gln. The mean intraocular pressure increased to 44 ± 3.5 mm Hg during intracameral irrigation (normal range 10.2 ± 0.4 mmHg). In vivo confocal microscopy results showed that the addition of Ala-Gln protected the morphology, structure, and density of the corneal endothelial cells. Optical Coherence Tomography (OCT) measurements showed that corneal thickness was not significantly different between the two groups, because of the immediate corneal edema after irrigation, but the addition of Ala-Gln obviously promoted the recovery of the corneal edema. Scanning electron microscopy indicated that the corneal endothelial cells were severely ruptured and exfoliated in the Ringer’s group accompanied with cellular edema, when compared with the Ala-Gln group. The intracameral irrigation using Ala-Gln protected the structure and expression of cytoskeleton and Na-K-ATPase, which exhibited a regular distribution and significantly increased expression in comparison to Ringer’s group. Furthermore, Ala-Gln maintained the mitochondrial morphology and increased the activity of mitochondria. Moreover, transmission electron microscopy showed that intracameral irrigation of Ala-Gln reversed the ultrastructural changes induced by the acute ocular hypertension in mice. Our study demonstrates that the intracameral irrigation of Ala-Gln effectively maintained the corneal endothelial pump function and barrier function by protecting the mitochondrial function and preventing the rearrangement of cytoskeleton in acute ocular hypertension in mice.
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Affiliation(s)
- Mengyi Jin
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Yanzi Wang
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Yixin Wang
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Yunpeng Li
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Guoliang Wang
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Xuezhi Liu
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Yuhua Xue
- School of Pharmaceutical Sciences, Xiamen University, Xiamen, China
| | - Zuguo Liu
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
| | - Cheng Li
- Eye Institute & Affiliated Xiamen Eye Center, School of Medicine, Xiamen University, Xiamen, China.,Fujian Provincial Key Laboratory of Ophthalmology and Visual Science, Xiamen, China
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30
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DeParis SW, Zhu AY, Majumdar S, Tian J, Elisseeff J, Jun AS, Mahoney NR. Effects of collagen crosslinking on porcine and human tarsal plate. BMC Ophthalmol 2019; 19:255. [PMID: 31842794 PMCID: PMC6915903 DOI: 10.1186/s12886-019-1254-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Accepted: 11/21/2019] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Floppy eyelid syndrome is a disorder in which the tarsal plate is easily distensible and is currently treated with conservative or surgical measures. Human tarsal plate contains type I collagen, which is crosslinked in corneal tissue as a treatment for keratoconus. We hypothesized that collagen crosslinking would similarly stiffen tarsal plate tissue and investigated this in porcine and human tarsal plate specimens. METHODS Riboflavin-sensitized porcine and human tarsus samples were irradiated with ultraviolet-A light. Porcine experiments were analyzed with gross photographs, anterior segment optical computed tomography (AS-OCT) imaging, and tensile testing. A prospective study of human tarsus was performed on samples from patients undergoing wedge resection for floppy eyelid syndrome and was analyzed with AS-OCT and tensile testing. RESULTS 73 porcine adnexa and 9 patients (16 eyelids) who underwent wedge excision were included in the study. Grossly, greater stiffness was observed in crosslinked porcine tissue. AS-OCT imaging in porcine tissue showed a distinct hyperreflective band in crosslinked specimens whose area and intensity increased with longer treatment time (P = 0.003); this band was also visible in crosslinked human specimens. Tensile testing was performed, but results were not statistically significant. CONCLUSIONS AS-OCT imaging, which has not been previously described for tarsal plate, showed a characteristic change in crosslinked porcine and human specimens. Tissue stiffness was increased grossly, but changes in tensile properties were not statistically significant. Further study is warranted to determine relevance as a potential treatment for floppy eyelid syndrome.
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Affiliation(s)
- Sarah W DeParis
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA
| | - Angela Y Zhu
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA
| | - Shoumyo Majumdar
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA
| | - Jing Tian
- Department of Biostatistics, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Jennifer Elisseeff
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA.,Department of Biomedical Engineering, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Albert S Jun
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA
| | - Nicholas R Mahoney
- Department of Ophthalmology, Wilmer Eye Institute, Johns Hopkins Hospital, 600 North Wolfe Street, Baltimore, MD, 21287, USA.
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31
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Uyanıklar M, Günal G, Tevlek A, Hosseinian P, Aydin HM. Hybrid Cornea: Cell Laden Hydrogel Incorporated Decellularized Matrix. ACS Biomater Sci Eng 2019; 6:122-133. [DOI: 10.1021/acsbiomaterials.9b01286] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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32
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Ting DSJ, Said DG, Dua HS. Are Descemet Membrane Ruptures the Root Cause of Corneal Hydrops in Keratoconic Eyes? Am J Ophthalmol 2019; 205:204. [PMID: 31296334 DOI: 10.1016/j.ajo.2019.04.038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 04/26/2019] [Indexed: 12/26/2022]
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33
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Zhao K, Wang X, Chen W, He R, Li X, Gao Y. [A comparative study of viscoelasticity between normal cornea and keratoconus]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2019; 36:613-618. [PMID: 31441262 PMCID: PMC10319497 DOI: 10.7507/1001-5515.201812052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/29/2018] [Indexed: 11/03/2022]
Abstract
Study of the mechanical properties of in vivo corneal materials is an important basis for further study of corneal physiological and pathological phenomena by means of finite element method. In this paper, the elastic coefficient ( E) and viscous coefficient ( η) of normal cornea and keratoconus under pulse pressure are calculated by using standard linear solid model with the data provided by corneal visualization scheimpflug technology. The results showed that there was a significant difference of E and η between normal cornea and keratoconus cornea ( P < 0.05). Receiver operating characteristic curve analysis showed that the area under curve (AUC) for E, η and their combined indicators were 0.776, 0.895 and 0.948, respectively, which indicated that keratoconus could be predicted by E and η. The results of this study may provide a reference for the early diagnosis of keratoconus and avoid the occurrence of keratoconus after operation, so it has a certain clinical value.
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Affiliation(s)
- Kechao Zhao
- School of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P.R.China
| | - Xiaojun Wang
- School of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P.R.China;School of Mechanical and Transportation Engineering, Taiyuan University of Technology, Taiyuan 030024,
| | - Weiyi Chen
- School of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P.R.China
| | - Rui He
- Department of Excimer Laser, Shanxi Eye Hospital, Taiyuan 030002, P.R.China
| | - Xiaona Li
- School of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P.R.China
| | - Yan Gao
- Department of Excimer Laser, Shanxi Eye Hospital, Taiyuan 030002, P.R.China
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Tarnawska D, Jastrzebska M, Chrobak E, Kadela-Tomanek M, Weglarz B, Boryczka G, Dobrowolski D, Chełmecka E, Wrzalik R. Endogenous fluorescence can differentiate the keratoconic cornea. Exp Eye Res 2019; 181:178-184. [PMID: 30735658 DOI: 10.1016/j.exer.2019.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 01/03/2019] [Accepted: 02/03/2019] [Indexed: 11/15/2022]
Abstract
The purpose of the study was to investigate the endogenous fluorescence of the keratoconic cornea in order to analyze changes in the spectra due to the keratoconic stroma abnormalities. Twenty-two corneal buttons obtained from patients with keratoconus (KC, N = 22) at the time of penetrating keratoplasty were used. As a reference, twelve normal corneas (N = 12): ten from the Eye Bank and two from enucleated eyes due to choroidal melanoma were used. The fluorescence excitation/emission matrices (EEM) in the ranges of 250-400/260-600 nm were recorded. Healthy cornea, keratoconic cornea and sclera showed three main EEM bands, which correspond to the following fluorophores: tryptophan residues in the proteoglycan fraction of corneal/scleral stromas, naturally occurring collagen cross-links and the NAD(P)H fraction present in the metabolically active cells. Relative intensity factors S1, S2 and S3 describing the contribution of each kind of fluorophore to the total fluorescence of the tissue were calculated. Normal and keratoconic corneas show qualitatively similar fluorescence matrices, but the statistically significant differences in the mean values of the S1, S2 and S3 parameters for the KC and normal corneas were observed indicating changes in contribution of different fluorophores to the whole fluorescence of the tissue. Moreover, differences between multidimensional distribution of the relative intensity factors S1, S2 and S3 between these groups were demonstrated (p < 0.001). In conclusions: Differences in the relative intensity factors calculated on a basis of the fluorescence spectra can correspond to the changes found in the KC stroma regarding natural collagen cross-links and the proteoglycan fraction. These parameters well differentiate the KC and normal corneas that could serve as an additional tool for the keratoconus characterization.
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Affiliation(s)
- Dorota Tarnawska
- Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland; Department of Ophthalmology, District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland
| | - Maria Jastrzebska
- Department of Solid State Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland.
| | - Elwira Chrobak
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, 41-200 Sosnowiec, Jagiellońska 4, Poland
| | - Monika Kadela-Tomanek
- Department of Organic Chemistry, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, 41-200 Sosnowiec, Jagiellońska 4, Poland
| | - Beata Weglarz
- Department of Ophthalmology, District Railway Hospital, Panewnicka 65, 40-760 Katowice, Poland
| | - Grzegorz Boryczka
- Faculty of Medicine in Katowice, Medical University of Silesia, 40-752 Katowice, Medyków 18, Poland
| | - Dariusz Dobrowolski
- Department of Ophthalmology with Pediatric Unit & Tissue and Cells Bank, St. Barbara Hospital, Trauma Center, Plac Medyków 1, 41-200 Sosnowiec, Poland; Chair and Clinical Department of Ophthalmology, Faculty of Medicine and Division of Dentistry in Zabrze, Medical University of Silesia, 40-760 Katowice, Panewnicka 65, Poland
| | - Elżbieta Chełmecka
- Department of Statistics, School of Pharmacy with the Division of Laboratory Medicine, Medical University of Silesia, 41-200 Sosnowiec, Ostrogórska 30, Poland; Department of Instrumental Analysis, School of Pharmacy with the Division of Laboratory Medicine, Medical University of Silesia, 41-200 Sosnowiec, Ostrogórska 30, Poland
| | - Roman Wrzalik
- Department of Biophysics and Molecular Physics, A. Chelkowski Institute of Physics, Silesian Center for Education and Interdisciplinary Research, University of Silesia, 41-500 Chorzów, 75 Pułku Piechoty 1A, Poland
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Differences in corneo-scleral topographic profile between healthy and keratoconus corneas. Cont Lens Anterior Eye 2019; 42:75-84. [DOI: 10.1016/j.clae.2018.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 05/11/2018] [Accepted: 05/17/2018] [Indexed: 11/20/2022]
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Lewis PN, White TL, Feneck EM, Young RD, Meek KM. Elastin Content and Distribution in Endothelial Keratoplasty Tissue Determines Direction of Scrolling. Am J Ophthalmol 2019; 197:181-182. [PMID: 30297218 DOI: 10.1016/j.ajo.2018.08.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 08/30/2018] [Indexed: 01/17/2023]
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Sharif R, Bak-Nielsen S, Hjortdal J, Karamichos D. Pathogenesis of Keratoconus: The intriguing therapeutic potential of Prolactin-inducible protein. Prog Retin Eye Res 2018; 67:150-167. [PMID: 29758268 PMCID: PMC6235698 DOI: 10.1016/j.preteyeres.2018.05.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 04/25/2018] [Accepted: 05/08/2018] [Indexed: 12/15/2022]
Abstract
Keratoconus (KC) is the most common ectatic corneal disease, with clinical findings that include discomfort, visual disturbance and possible blindness if left untreated. KC affects approximately 1:400 to 1:2000 people worldwide, including both males and females. The aetiology and onset of KC remains a puzzle and as a result, the ability to treat or reverse the disease is hampered. Sex hormones are known to play a role in the maintenance of the structure and integrity of the human cornea. Hormone levels have been reported to alter corneal thickness, curvature, and sensitivity during different times of menstrual cycle. Surprisingly, the role of sex hormones in corneal diseases and KC has been largely neglected. Prolactin-induced protein, known to be regulated by sex hormones, is a new KC biomarker that has been recently proposed. Studies herein discuss the role of sex hormones as a control mechanism for KC onset and progression and evidence supporting the view that prolactin-induced protein is an important hormonally regulated biomarker in KC is discussed.
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Affiliation(s)
- Rabab Sharif
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma City, OK 73104, United States
| | - Sashia Bak-Nielsen
- Department of Ophthalmology, Aarhus University Hospital, Aarhus DK-8200, Denmark
| | - Jesper Hjortdal
- Department of Ophthalmology, Aarhus University Hospital, Aarhus DK-8200, Denmark
| | - Dimitrios Karamichos
- Department of Cell Biology, University of Oklahoma Health Sciences Center, 975 NE 10th Street, Oklahoma City, OK 73104, United States; Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Science Center, 608 Stanton L. Young Blvd, Oklahoma City, OK 73104, United States.
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Nasrin F, Iyer RV, Mathews SM. Simultaneous Estimation of Corneal Topography, Pachymetry, and Curvature. IEEE TRANSACTIONS ON MEDICAL IMAGING 2018; 37:2463-2473. [PMID: 29994760 DOI: 10.1109/tmi.2018.2836304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Identification of objective criteria to correctly diagnose ectatic diseases of the cornea or to detect early stages of corneal ectasia is of great interest in ophthalmology and optometry. Metrics for diagnosis typically employed are curvature maps (axial/sagittal, tangential); elevation map of the anterior surface of the cornea with respect to a reference sphere; and pachymetry (thickness) map of the cornea. We present evidence that currently used curvature maps do not represent the actual curvatures (principal or mean) in a human cornea. A novel contribution of this paper is the computation of the true mean curvature over every point of a central region of the cornea. We show that the true mean curvature can accurately identify the location of the ectasia. We present a quartic smoothing spline algorithm for the simultaneous computation of elevation maps for anterior and posterior corneal surfaces, pachymetry, and true mean curvature. The input to the algorithm is data from a single measurement from imaging devices such as an anterior segment optical coherence tomographer or a Scheimpflug imager. We show that a different combination of metrics is useful for the diagnosis of existing ectasia (true mean curvature and anterior elevation map) as opposed to subclinical ectasia (pachymetry and posterior elevation map). We compare our results with existing algorithms, and present applications to a normal cornea, a forme fruste keratoconic cornea, and an advanced keratoconic cornea.
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Kitazawa K, Itoi M, Yokota I, Wakimasu K, Cho Y, Nakamura Y, Hieda O, Kinoshita S, Sotozono C. Involvement of anterior and posterior corneal surface area imbalance in the pathological change of keratoconus. Sci Rep 2018; 8:14993. [PMID: 30302021 PMCID: PMC6177437 DOI: 10.1038/s41598-018-33490-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/26/2018] [Indexed: 12/19/2022] Open
Abstract
Keratoconus (KC) is an ectatic disorder with a high prevalence rate. However, the exact cause of the disease and possible underlying mechanisms of development remain unclear. In this present study, we aimed to investigate the anterior and the posterior corneal surface area in normal, forme fruste keratoconus (FFKC), and keratoconic eyes (as a reference group) using anterior segment optical coherence tomography (AS-OCT) in order to assess the pathological change of KC. The surface areas of the anterior or posterior cornea, and the anterior-posterior (As/Ps) ratio of corneal surface area, were measured at the central 5.0 mm-, 6.0 mm-, and 7.0 mm-diameter areas via AS-OCT, and a comparison between the normal eyes and FFKC eyes was then performed using the Mann-Whitney U test. The posterior surface area at the central 5.0 mm areas in the FFKC eyes (20.430 mm2) and KC eyes (20.917 mm2) seemed to become larger than that of normal eyes (20.389 mm2) (normal vs FFKC; P = 0.06). Moreover, the As/Ps of the corneal surface area in the FFKC eyes (0.986) and the KC eyes (0.976) was significantly smaller than that of the normal eyes (0.988) (normal vs FFKC; P < 0.01). Anterior and posterior corneal surface area imbalance may reflect keratoconic eyes at the early stage of the disease.
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Affiliation(s)
- Koji Kitazawa
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan. .,Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan. .,Baptist Eye Institute, Kyoto, Japan.
| | - Motohiro Itoi
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Isao Yokota
- Department of Biostatistics, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | | | - Yuko Cho
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Yo Nakamura
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Osamu Hieda
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Shigeru Kinoshita
- Department of Frontier Medical Science and Technology for Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Chie Sotozono
- Department of Ophthalmology, Kyoto Prefectural University of Medicine, Kyoto, Japan
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40
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Mohammed I, Ross AR, Britton JO, Said DG, Dua HS. Elastin Content and Distribution in Endothelial Keratoplasty Tissue Determines Direction of Scrolling. Am J Ophthalmol 2018; 194:16-25. [PMID: 30026084 DOI: 10.1016/j.ajo.2018.07.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 05/20/2018] [Accepted: 07/04/2018] [Indexed: 02/06/2023]
Abstract
PURPOSE Descemet membrane endothelial keratoplasty (DMEK) and pre-Descemet endothelial keratoplasty (PDEK) tissues always scroll with the endothelial cells (EC) outside. We designed a study to understand the reason for this behavior. DESIGN Experimental study. METHODS Elastin content in Descemet membrane (DM), pre-Descemet layer (PDL), central and peripheral stroma, sclera, and trabecular meshwork were measured by the Fastin elastin assay kit. Distribution of elastin in DM, PDL, and anterior lens capsule (ALC) were examined by immunohistology. The effect of recombinant elastase enzyme and the effect of complete removal of EC and epithelial cells on the scrolling of DM and ALC, respectively, were studied. RESULTS PDL showed the highest elastin content among the different tissues studied. Elastin localized as a distinct anterior band in the DM and was uniformly distributed in the PDL demarcating the latter from corneal stroma. Enzymatic treatment of DM with elastase reversed scrolling and corresponded with degradation or disappearance of elastin. Removal of EC did not affect the direction of scrolling. ALC behaved in the same manner with regard to distribution of elastin, scrolling, and removal of epithelial cells. CONCLUSIONS This pattern of elastin distribution in DM explains why DMEK and PDEK tissues always scroll with the EC outside. This behavior is not influenced by the EC. High elastin content and uniform distribution in the PDL suggest a structural difference from the posterior stroma.
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Feneck EM, Lewis PN, Ralphs J, Meek KM. A comparative study of the elastic fibre system within the mouse and human cornea. Exp Eye Res 2018; 177:35-44. [PMID: 30053442 PMCID: PMC6280038 DOI: 10.1016/j.exer.2018.07.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/11/2018] [Accepted: 07/21/2018] [Indexed: 01/26/2023]
Abstract
The cornea relies on its organised extracellular matrix for maintaining transparency and biomechanical strength. Studies have identified an elastic fibre system within the human posterior cornea, thought to allow for slight deformations in response to internal pressure fluctuations within the eye. However, the type of elastic fibres that exist within the cornea and their roles remain elusive. The aim of this study was to compare the distribution and organisation of the elastic fibres within the posterior peripheral mouse and human cornea, and elucidate how these fibres integrate with the trabecular meshwork, whilst characterising the distribution of their main likely components (fibrillin-1, elastin and type VI collagen) in different parts of the cornea and adjacent sclera. We identified key differences in the elastic fibre system between the human and mouse cornea. True elastic fibres (containing elastin) were identified within the human posterior peripheral cornea. Elastic fibres appeared to present as an extensive network throughout the mouse corneal stroma, but as fibrillin-rich microfibril bundles rather than true elastic fibres. However, tropoelastin staining indicated the possibility that true elastic fibres had yet to develop in the young mice studied. Differences were also apparent within the anatomy of the trabecular meshwork. The human trabecular meshwork appeared to insert between the corneal stroma and Descemet's membrane, with elastic fibres continuing into the stroma from the trabecular meshwork anterior to Descemet's membrane. Within the mouse cornea, no clear insertion point of the trabecular meshwork was seen, instead the elastic fibres within the trabecular meshwork continued into Descemet's membrane, with the trabecular meshwork joining posterior to Descemet's membrane. True Elastic fibres (containing elastin) occur within the human posterior peripheral cornea. A fibrillin-rich microfibril system was found throughout the mouse corneal stroma, with no apparent true elastic fibres. Human trabecular meshwork inserts between the posterior corneal stroma and Descemet's membrane. A continuity of elastic fibres was identified between cornea and trabecular meshwork in both species.
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Affiliation(s)
- Eleanor M Feneck
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Philip N Lewis
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
| | - Jim Ralphs
- School of Biosciences, Cardiff University, Cathays Park, Cardiff, CF10 3AX, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
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Ma J, Wang Y, Wei P, Jhanji V. Biomechanics and structure of the cornea: implications and association with corneal disorders. Surv Ophthalmol 2018; 63:851-861. [PMID: 29857022 DOI: 10.1016/j.survophthal.2018.05.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 05/17/2018] [Accepted: 05/21/2018] [Indexed: 12/14/2022]
Abstract
Recent studies have shown that alterations in corneal biomechanical properties are associated with corneal pathologies, particularly corneal ectasia. Moreover, these alterations may have implications with regard to the outcomes of therapeutic modalities and corneal refractive surgeries. We address corneal anatomy and its relevance to corneal biomechanical characteristics, as well as ocular and systemic conditions associated with changes in corneal biomechanics.
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Affiliation(s)
- Jiaonan Ma
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China; Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Naikai University, Tianjin Medical University, Tianjin, China.
| | - Pinghui Wei
- Tianjin Eye Hospital, Tianjin Eye Institute, Tianjin Key Laboratory of Ophthalmology and Visual Science, Naikai University, Tianjin Medical University, Tianjin, China
| | - Vishal Jhanji
- UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Axial mechanical and structural characterization of keratoconus corneas. Exp Eye Res 2018; 175:14-19. [PMID: 29842851 DOI: 10.1016/j.exer.2018.05.019] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/13/2018] [Accepted: 05/18/2018] [Indexed: 11/23/2022]
Abstract
PURPOSE Previous studies indicate that there is an axial gradient of collagen lamellar branching and anastomosing leading to regional differences in corneal tissue stiffness that may control corneal shape. To further test this hypothesis we have measured the axial material stiffness and quantified the collagen lamellar complexity in ectatic and mechanically weakened keratoconus corneas (KC). METHODS Acoustic radiation force elastic microscopy (ARFEM) was used to probe the axial mechanical properties of the cone region of three donor KC buttons. 3 Dimensional second harmonic generation microscopy (3D-SHG) was used to qualitatively evaluate lamellar organization in 3 kC buttons and quantitatively measure lamellar branching point density (BPD) in a separate KC button that had been treated with epikeratophakia (Epi-KP). RESULTS The mean elastic modulus for the KC corneas was 1.67 ± 0.44 kPa anteriorly and 0.970 ± 0.30 kPa posteriorly, substantially below that previously measured for normal human cornea. 3D-SHG of KC buttons showed a simplified collagen lamellar structure lacking noticeable angled lamellae in the region of the cone. BPD in the anterior, posterior, central and paracentral regions of the KC cornea were significantly lower than in the overlying Epi-KP lenticule. Additionally, BPD in the cone region was significantly lower than the adjacent paracentral region in the KC button. CONCLUSIONS The KC cornea exhibits an axial gradient of mechanical stiffness and a BPD that appears substantially lower in the cone region compared to normal cornea. The findings reinforce the hypothesis that collagen architecture may control corneal mechanical stiffness and hence corneal shape.
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The hierarchical response of human corneal collagen to load. Acta Biomater 2018; 65:216-225. [PMID: 29128531 PMCID: PMC5729024 DOI: 10.1016/j.actbio.2017.11.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 11/05/2017] [Accepted: 11/07/2017] [Indexed: 02/04/2023]
Abstract
Fibrillar collagen in the human cornea is integral to its function as a transparent lens of precise curvature, and its arrangement is now well-characterised in the literature. While there has been considerable effort to incorporate fibrillar architecture into mechanical models of the cornea, the mechanical response of corneal collagen to small applied loads is not well understood. In this study the fibrillar and molecular response to tensile load was quantified using small and wide angle X-ray scattering (SAXS/WAXS), and digital image correlation (DIC) photography was used to calculate the local strain field that gave rise to the hierarchical changes. A molecular scattering model was used to calculate the tropocollagen tilt relative to the fibril axis and changes associated with applied strain. Changes were measured in the D-period, molecular tilt and the orientation and spacing of the fibrillar and molecular networks. These measurements were summarised into hierarchical deformation mechanisms, which were found to contribute at varying strains. The change in molecular tilt is indicative of a sub-fibrillar “spring-like” deformation mechanism, which was found to account for most of the applied strain under physiological and near-physiological loads. This deformation mechanism may play an important functional role in tissues rich in fibrils of high helical tilt, such as skin and cartilage. Statement of Significance Collagen is the primary mediator of soft tissue biomechanics, and variations in its hierarchical structure convey the varying amounts of structural support necessary for organs to function normally. Here we have examined the structural response of corneal collagen to tensile load using X-rays to probe hierarchies ranging from molecular to fibrillar. We found a previously unreported deformation mechanism whereby molecules, which are helically arranged relative to the axis of their fibril, change in tilt akin to the manner in which a spring stretches. This “spring-like” mechanism accounts for a significant portion of the applied deformation at low strains (<3%). These findings will inform the future design of collagen-based artificial corneas being developed to address world-wide shortages of corneal donor tissue.
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