1
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Reduced OPA1, Mitochondrial Fragmentation and Increased Susceptibility to Apoptosis in Granular Corneal Dystrophy Type 2 Corneal Fibroblasts. Genes (Basel) 2023; 14:genes14030566. [PMID: 36980838 PMCID: PMC10048436 DOI: 10.3390/genes14030566] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 02/20/2023] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
The progressive degeneration of granular corneal dystrophy type 2 (GCD2) corneal fibroblasts is associated with altered mitochondrial function, but the underlying mechanisms are incompletely understood. We investigated whether an imbalance of mitochondrial dynamics contributes to mitochondrial dysfunction of GCD2 corneal fibroblasts. Transmission electron microscopy revealed several small, structurally abnormal mitochondria with altered cristae morphology in GCD2 corneal fibroblasts. Confocal microscopy showed enhanced mitochondrial fission and fragmented mitochondrial tubular networks. Western blotting revealed higher levels of MFN1, MFN2, and pDRP1 and decreased levels of OPA1 and FIS1 in GCD2. OPA1 reduction by short hairpin RNA (shRNA) resulted in fragmented mitochondrial tubular networks and increased susceptibility to mitochondrial stress-induced apoptosis. A decrease in the mitochondrial biogenesis-related transcription factors NRF1 and PGC1α was observed, while there was an increase in the mitochondrial membrane proteins TOM20 and TIM23. Additionally, reduced levels of mitochondrial DNA (mtDNA) were exhibited in GCD2 corneal fibroblasts. These observations suggest that altered mitochondrial fission/fusion and biogenesis are the critical molecular mechanisms that cause mitochondrial dysfunction contributing to the degeneration of GCD2 corneal fibroblasts.
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2
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Sklenářová R, Akla N, Latorre MJ, Ulrichová J, Franková J. Collagen as a Biomaterial for Skin and Corneal Wound Healing. J Funct Biomater 2022; 13:jfb13040249. [PMID: 36412890 PMCID: PMC9680244 DOI: 10.3390/jfb13040249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/11/2022] [Accepted: 11/15/2022] [Indexed: 11/18/2022] Open
Abstract
The cornea and the skin are two organs that form the outer barrier of the human body. When either is injured (e.g., from surgery, physical trauma, or chemical burns), wound healing is initiated to restore integrity. Many cells are activated during wound healing. In particular, fibroblasts that are stimulated often transition into repair fibroblasts or myofibroblasts that synthesize extracellular matrix (ECM) components into the wound area. Control of wound ECM deposition is critical, as a disorganized ECM can block restoration of function. One of the most abundant structural proteins in the mammalian ECM is collagen. Collagen type I is the main component in connective tissues. It can be readily obtained and purified, and short analogs have also been developed for tissue engineering applications, including modulating the wound healing response. This review discusses the effect of several current collagen implants on the stimulation of corneal and skin wound healing. These range from collagen sponges and hydrogels to films and membranes.
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Affiliation(s)
- Renáta Sklenářová
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University in Olomouc, 775 15 Olomouc, Czech Republic
- Maisonneuve-Rosemont Hospital Research Centre, Montréal, QC H1T 2M4, Canada
| | - Naoufal Akla
- Maisonneuve-Rosemont Hospital Research Centre, Montréal, QC H1T 2M4, Canada
- Department of Ophthalmology, Université de Montréal, Montréal, QC H3C 3J7, Canada
| | | | - Jitka Ulrichová
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University in Olomouc, 775 15 Olomouc, Czech Republic
| | - Jana Franková
- Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University in Olomouc, 775 15 Olomouc, Czech Republic
- Correspondence:
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3
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Stanton CM, Findlay AS, Drake C, Mustafa MZ, Gautier P, McKie L, Jackson IJ, Vitart V. A Mouse Model of Brittle Cornea Syndrome caused by mutation in Zfp469. Dis Model Mech 2021; 14:272230. [PMID: 34368841 PMCID: PMC8476817 DOI: 10.1242/dmm.049175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 07/28/2021] [Indexed: 11/20/2022] Open
Abstract
Brittle cornea syndrome (BCS) is a rare recessive condition characterised by extreme thinning of the cornea and sclera. BCS results from loss-of-function mutations in the poorly understood genes ZNF469 or PRDM5. In order to determine the function of ZNF469 and to elucidate pathogenic mechanisms, we used genome editing to recapitulate a human ZNF469 BCS mutation in the orthologous mouse gene Zfp469. Ophthalmic phenotyping showed that homozygous Zfp469 mutation causes significant central and peripheral corneal thinning arising from reduced stromal thickness. Expression of key components of the corneal stroma in primary keratocytes from Zfp469BCS/BCS mice is affected, including decreased Col1a1 and Col1a2 expression. This alters the collagen type I/collagen type V ratio and results in collagen fibrils with smaller diameter and increased fibril density in homozygous mutant corneas, correlating with decreased biomechanical strength in the cornea. Cell-derived matrices generated by primary keratocytes show reduced deposition of collagen type I, offering an in vitro model for stromal dysfunction. Work remains to determine whether modulating ZNF469 activity will have therapeutic benefit in BCS or in conditions such as keratoconus in which the cornea thins progressively. This article has an associated First Person interview with the first author of the paper. Summary: A mouse model of brittle cornea syndrome was created to elucidate molecular mechanisms underlying the pathology of this rare connective tissue disorder in which extremely thin corneas rupture, causing irreversible blindness.
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Affiliation(s)
- Chloe M Stanton
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Amy S Findlay
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Camilla Drake
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Mohammad Z Mustafa
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Philippe Gautier
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Lisa McKie
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Ian J Jackson
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
| | - Veronique Vitart
- MRC Human Genetics Unit, Institute of Genetics & Cancer, The University of Edinburgh, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
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4
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Eleiwa TK, Elsawy A, Syed ZA, Roongpoovapatr V, Sayed AM, Yoo SH, Abou Shousha M. In-vivo Three-dimensional Characteristics of Bowman's Layer and Endothelium/Descemet's Complex Using Corneal Microlayer Tomography in Healthy Subjects. Curr Eye Res 2020; 45:659-667. [PMID: 32064952 DOI: 10.1080/02713683.2019.1691238] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Purpose: To characterize the three-dimensional (3D) thickness profile and age-related changes of Bowman's layer (BL), and endothelium/Descemet's membrane (En/DM) complex among healthy individuals using Corneal Microlayer Tomography (CML-T), and to describe its repeatability and accuracy.Methods: Sixty-six eyes of 41 healthy volunteers; 27 eyes (< 40 years old), and 39 eyes (>40 years old) were imaged using HD-OCT. Automatic and manual segmentation of the corneal layers was performed, and 3D thickness maps were generated, using custom-built CML-T software. A regional analysis of mean thickness parameters between the 2 age groups was performed. A regression analysis was used to assess the correlation between age, and thickness maps. Intraclass Correlation Coefficients (ICC), Coefficients of Variation (COV), and Bland-Altman plots were used to assess the reliability of the repeated measurements in 198 locations.Results: CML-T successfully mapped the BL and En/DM in all included eyes. Thickness maps showed a significant increase in corneal thickness (CT), BL thickness (BMT), and En/DM complex thickness (DMT) toward the periphery with a mean difference 28 µm (p < .001), 1.1 µm (p < .001), and 1.4 µm (p < .001), respectively. There was a strong correlation between age and central DMT (r = 0.61; p < .001), while there was no correlation between age and both CT, and BMT. ICC values ranged from 0.9 (BMT) to 0.997 (DMT), and from 0.808 (BMT) to 0.979 (CT) for intraoperator repeatability of manual measurements, and the accuracy of auto matic measurements, respectively. COV values were lower than 7.5% in all cases.Conclusion: CML-T is a novel tool that can generate 3D-thickness maps of both BL and En/DM. CT, BMT, and DMT increase toward the periphery in healthy corneas. DMT increases with aging, while BMT does not. We also report excellent repeatability, accuracy and good agreement between automatic and manual measurements.
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Affiliation(s)
- Taher K Eleiwa
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Department of Ophthalmology, Faculty of Medicine, Benha University, Benha, Egypt
| | - Amr Elsawy
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Electrical and Computer Engineering, University of Miami, Miami, FL, USA
| | - Zeba A Syed
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Wills Eye Hospital, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - Ahmed M Sayed
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Biomedical Engineering Department, Helwan University, Helwan, Egypt
| | - Sonia H Yoo
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Mohamed Abou Shousha
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL, USA.,Electrical and Computer Engineering, University of Miami, Miami, FL, USA.,Biomedical Engineering, University of Miami, Miami, FL, USA
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5
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Eleiwa TK, Cook JC, Elsawy AS, Roongpoovapatr V, Volante V, Yoo S, Abou Shousha M. Diagnostic Performance of Three-Dimensional Endothelium/Descemet Membrane Complex Thickness Maps in Active Corneal Graft Rejection. Am J Ophthalmol 2020; 210:48-58. [PMID: 31678558 DOI: 10.1016/j.ajo.2019.10.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 10/15/2019] [Accepted: 10/17/2019] [Indexed: 10/25/2022]
Abstract
PURPOSE To evaluate the performance of 3-dimensional (3D) endothelium/Descemet membrane complex thickness (En/DMT) maps vs total corneal thickness (TCT) maps in the diagnosis of active corneal graft rejection. DESIGN Cross-sectional study. METHODS Eighty-one eyes (32 clear grafts and 17 with active rejection, along with 32 age-matched control eyes) were imaged using high-definition optical coherence tomography (HD-OCT), and a custom-built segmentation algorithm was used to generate 3D color-coded maps of TCT and En/DMT of the central 6-mm cornea. Regional En/DMT and TCT were analyzed and compared between the studied groups. Receiver operating characteristic curves were used to determine the accuracy of En/DMT and TCT maps in differentiating between studied groups. Main outcome measures were regional En/DMT and TCT. RESULTS Both regional TCT and En/DMT were significantly greater in actively rejecting grafts compared to both healthy corneas and clear grafts (P < .001). Using 3D thickness maps, central, paracentral, and peripheral En/DMT achieved 100% sensitivity and 100% specificity in diagnosing actively rejecting grafts (optimal cut-off value [OCV] of 19 μm, 24 μm, and 26 μm, respectively), vs only 82% sensitivity and 96% specificity for central TCT, OCV of 587 μm. Moreover, central, paracentral, and peripheral En/DMT correlated significantly with graft rejection severity (r = 0.972, r = 0.729, and r = 0.823, respectively; P < .001). CONCLUSION 3D En/DMT maps can diagnose active corneal graft rejection with excellent accuracy, sensitivity, and specificity. Future longitudinal studies are required to evaluate the predictive and prognostic role of 3D En/DMT maps in corneal graft rejection.
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6
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The Use of Digital Microscopy to Compare the Thicknesses of Normal Corneas and Ex Vivo Rejected Corneal Grafts with a Focus on the Descemet's Membrane. J Ophthalmol 2019; 2019:8283175. [PMID: 31827912 PMCID: PMC6885265 DOI: 10.1155/2019/8283175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/05/2019] [Indexed: 01/15/2023] Open
Abstract
Objective To compare the thickness of corneal layers, specifically the Descemet's membrane (DM), in normal corneas and in failed grafts due to rejection (FGRs) using the digital histopathology and to propose a model for the measurement of corneal layers using this method. Methods This is a prospective, cross-sectional study performed at the MUHC-McGill University Ocular Pathology & Translational Research Laboratory (McGill University, Montreal, Canada). Histopathological sections of 25 normal human corneas and 40 FGRs were fully digitalized and examined. Inclusion criteria: samples diagnosed as normal corneas or FGRs, from patients older than 18 years of age. Exclusion criteria: histopathological sections without adequate tissue or missing epidemiological information. For each sample, the thicknesses of the epithelium, stroma, and DM were acquired. From a perpendicular plane of reference, two central measurements and two nasal and two temporal peripheral measurements were obtained. Results There were differences between the normal and FGR groups in the mean central thickness of the epithelium (p < 0.001), the nasal and temporal stromal regions (p < 0.001), and of the DM in the nasal and temporal regions (p < 0.001). Compared with the extremities of the sample (nasal and temporal), the mean thickness of the DM in normal corneas was lower in the central region (p < 0.001), and this difference was not found in the FGR group. Conclusions Normal corneas have a thinner epithelium in the central region than the FGR group. In addition, the stroma and DM thicknesses of the nasal and temporal periphery were significantly higher in normal corneas than in those from the FGR group. The digital microscopy protocol applied in this study may be useful for further research studies regarding cornea and other tissues.
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7
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Choi SI, Lee B, Woo JH, Jeong JB, Jun I, Kim EK. APP processing and metabolism in corneal fibroblasts and epithelium as a potential biomarker for Alzheimer's disease. Exp Eye Res 2019; 182:167-174. [PMID: 30930125 DOI: 10.1016/j.exer.2019.03.012] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/18/2019] [Accepted: 03/17/2019] [Indexed: 12/21/2022]
Abstract
Alzheimer's disease (AD) primarily affects the brain and is the most common form of dementia worldwide. Despite more than a century of research, there are still no early biomarkers for AD. It has been reported that AD affects the eye, which is more accessible for imaging than the brain; however, links with the cornea have not been evaluated. To investigate whether the cornea could be used to identify possible diagnostic indicators of AD, we analyzed the proteolytic processing and isoforms of amyloid precursor protein (APP) and evaluated the expression of AD-related genes and proteins in corneal fibroblasts from wild-type (WT) corneas and corneas from patients with granular corneal dystrophy type 2 (GCD2), which is related to amyloid formation in the cornea. Reverse transcription polymerase chain reaction (RT-PCR) analysis was used to assess the expression of AD-related genes, i.e., APP, ADAM10, BACE1, BACE2, PSEN1, NCSTN, IDE, and NEP. RT-PCR and DNA sequencing analysis demonstrated that isoforms of APP770 and APP751, but not APP695, were expressed in corneal fibroblasts. Moreover, the mRNA ratio of APP770/APP751 isoforms was approximately 4:1. Western blot analysis also demonstrated the expression of a disintegrin and metalloprotease domain-containing protein 10 (ADAM10), beta-site APP-cleaving enzyme 1 (BACE1), nicastrin, insulin degradation enzyme, and neprilysin in corneal fibroblasts. Among these targets, the levels of immature ADAM10 and BACE1 protein were significantly increased in GCD2 cells. The expression levels of APP, ADAM10, BACE1, and transforming growth factor-beta-induced protein (TGFBIp) were also detected by western blot in human corneal epithelium. We also investigated the effects of inhibition of the autophagy-lysosomal and ubiquitin-proteasomal proteolytic systems (UPS) on APP processing and metabolism. These pathway inhibitors accumulated APP, α-carboxy-terminal fragments (CTFs), β-CTFs, and the C-terminal APP intracellular domain (AICD) in corneal fibroblasts. Analysis of microRNAs (miRNAs) revealed that miR-9 and miR-181a negatively coregulated BACE1 and TGFBIp, which was directly associated with the pathogenesis of AD and GCD2, respectively. Immunohistochemical analysis indicated that APP and BACE1 were distributed in corneal stroma cells, epithelial cells, and the retinal layer in mice. Collectively, we propose that the cornea, which is the transparent outermost layer of the eye and thus offers easy accessibility, could be used as a potential biomarker for AD diagnosis and progression.
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Affiliation(s)
- Seung-Il Choi
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Boram Lee
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Jong Hwan Woo
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Jang Bin Jeong
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea
| | - Ikhyun Jun
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea; Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea
| | - Eung Kweon Kim
- Department of Ophthalmology, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul, South Korea; Institute of Vision Research, Yonsei University College of Medicine, Seoul, South Korea.
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8
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Fu D, Wang L, Zhou XT, Yu ZQ. Cap morphology after small-incision lenticule extraction and its effects on intraocular scattering. Int J Ophthalmol 2018; 11:456-461. [PMID: 29600180 DOI: 10.18240/ijo.2018.03.16] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 10/14/2017] [Indexed: 11/23/2022] Open
Abstract
AIM To investigate cap morphology after small-incision lenticule extraction (SMILE) and its effects on intraocular scattering. METHODS Sixty-five eyes of 33 patients undergoing SMILE were enrolled. In addition to regular evaluation, Fourier-domain optical coherence tomography was used to investigate cap thickness at 1d, 1wk, 1 and 3mo postoperatively. The optical quality including modulation transfer function cutoff frequency, Strehl ratio, Optical Quality Analysis System (OQAS) values, and objective scattering index (OSI), were evaluated using OQAS™. RESULTS Cap thickness decreased from 1d to 1wk (P<0.001), but remained higher than intended thickness of 120 µm after 3mo (P<0.001). Cap thickness in central area was thinner than that of in the paracentral and peripheral areas (P<0.0001). Total number of microdistortions decreased from 1d to 3mo (P<0.0001). Pearson analysis revealed a weak correlation between OSI and standard deviation of cap thickness at 1d and 1mo, as well as between range of cap thickness and OSI at 1mo. No correlation was found between microdistortion and OSI, but a negative correlation existed between microdistortion and range at 1d and 1moafter surgery. CONCLUSION The corneal cap tends to be more accurate and regular with time lapse. Better cap morphology tends to contribute less intraocular scattering in the eyes undergoing SMILE.
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Affiliation(s)
- Dan Fu
- Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Lin Wang
- Eye and ENT Hospital of Fudan University, Shanghai 200031, China
| | - Xing-Tao Zhou
- Eye and ENT Hospital of Fudan University, Shanghai 200031, China.,Myopia Key Laboratory of the Health Ministry, Shanghai 200031, China
| | - Zhi-Qiang Yu
- Eye and ENT Hospital of Fudan University, Shanghai 200031, China.,Myopia Key Laboratory of the Health Ministry, Shanghai 200031, China
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9
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Obtaining Thickness Maps of Corneal Layers Using the Optimal Algorithm for Intracorneal Layer Segmentation. Int J Biomed Imaging 2016; 2016:1420230. [PMID: 27247559 PMCID: PMC4876237 DOI: 10.1155/2016/1420230] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 03/11/2016] [Accepted: 04/06/2016] [Indexed: 11/18/2022] Open
Abstract
Optical Coherence Tomography (OCT) is one of the most informative methodologies in ophthalmology and provides cross sectional images from anterior and posterior segments of the eye. Corneal diseases can be diagnosed by these images and corneal thickness maps can also assist in the treatment and diagnosis. The need for automatic segmentation of cross sectional images is inevitable since manual segmentation is time consuming and imprecise. In this paper, segmentation methods such as Gaussian Mixture Model (GMM), Graph Cut, and Level Set are used for automatic segmentation of three clinically important corneal layer boundaries on OCT images. Using the segmentation of the boundaries in three-dimensional corneal data, we obtained thickness maps of the layers which are created by these borders. Mean and standard deviation of the thickness values for normal subjects in epithelial, stromal, and whole cornea are calculated in central, superior, inferior, nasal, and temporal zones (centered on the center of pupil). To evaluate our approach, the automatic boundary results are compared with the boundaries segmented manually by two corneal specialists. The quantitative results show that GMM method segments the desired boundaries with the best accuracy.
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10
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López de la Fuente C, Sánchez-Cano A, Segura F, Hospital EO, Pinilla I. Evaluation of Total Corneal Thickness and Corneal Layers With Spectral-Domain Optical Coherence Tomography. J Refract Surg 2016; 32:27-32. [DOI: 10.3928/1081597x-20151207-03] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/30/2023]
Abstract
PURPOSE:
To evaluate total corneal thickness and corneal layers in healthy young adults using spectral-domain optical coherence tomography and to describe its repeatability and reproducibility.
METHODS:
Eighty-six eyes from 86 healthy volunteers were prospectively and consecutively enrolled. Manual measurements of central corneal thickness (CCT) and central thickness of epithelium, Bowman's layer, stroma, and the Descemet–endothelium complex were performed using Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany). To assess the reliability of the repeated measurements, intraclass correlation coefficients and coefficients of variation were used.
RESULTS:
Mean CCT, epithelium, Bowman's layer, stroma, and Descemet–endothelium values were 555.50 ± 29.64, 54.60 ± 4.25, 16.70 ± 1.73, 467.51 ± 28.91, and 16.74 ± 1.66
µ
m, respectively. The intraclass correlation coefficients ranged from 0.746 (Bowman's layer) to 0.999 (CCT and stroma) and from 0.483 (Bowman's layer) to 0.995 (CCT) and 0.998 (stroma) for intraobserver repeatability and interobserver reproducibility, respectively. The measurements showed coefficients of variation lower than 11% in all cases.
CONCLUSIONS:
This study establishes a normal database for corneal thickness and all its layers in healthy young adults with spectral-domain optical coherence tomography. This device exhibited a high degree of intraobserver repeatability and interobserver reproducibility for all regions except Bowman's layer.
[
J Refract Surg.
2016;32(1):27–32.]
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11
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Massoudi D, Malecaze F, Galiacy SD. Collagens and proteoglycans of the cornea: importance in transparency and visual disorders. Cell Tissue Res 2015. [PMID: 26205093 DOI: 10.1007/s00441-015-2233-5] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cornea represents the external part of the eye and consists of an epithelium, a stroma and an endothelium. Due to its curvature and transparency this structure makes up approximately 70% of the total refractive power of the eye. This function is partly made possible by the particular organization of the collagen extracellular matrix contained in the corneal stroma that allows a constant refractive power. The maintenance of such an organization involves other molecules such as type V collagen, FACITs (fibril-associated collagens with interrupted triple helices) and SLRPs (small leucine-rich proteoglycans). These components play crucial roles in the preservation of the correct organization and function of the cornea since their absence or modification leads to abnormalities such as corneal opacities. Thus, the aim of this review is to describe the different corneal collagens and proteoglycans by highlighting their importance in corneal transparency as well as their implication in corneal visual disorders.
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Affiliation(s)
| | - Francois Malecaze
- EA4555, Université Toulouse III Paul Sabatier, Toulouse, France
- CHU Toulouse, Hôpital Purpan, Service d'Ophtalmologie, Toulouse, France
| | - Stephane D Galiacy
- EA4555, Université Toulouse III Paul Sabatier, Toulouse, France.
- CHU Toulouse, Hôpital Purpan, Service d'Ophtalmologie, Toulouse, France.
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