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Shu N, He Y, Zhang Y. Research progress on measurement methods and clinical applications of corneal elastic modulus. Exp Eye Res 2024; 245:109974. [PMID: 38897271 DOI: 10.1016/j.exer.2024.109974] [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: 03/19/2024] [Revised: 06/07/2024] [Accepted: 06/16/2024] [Indexed: 06/21/2024]
Abstract
Various corneal diseases are strongly associated with corneal biomechanical characteristics, and early measurement of patients' corneal biomechanics can be utilized in their diagnosis and treatment. Measurement methods for corneal biomechanical characteristics are classified into ex vivo and in vivo. Some of these methods can directly measure certain corneal biomechanical parameters, while others require indirect calculation through alternative methods. However, due to diversities in measurement techniques and environmental conditions, significant differences may exist in the corneal mechanical properties measured by these two methods. Therefore, comprehensive research on current measurement methods and the exploration of novel measurement techniques may have great clinical significance. The corneal elastic modulus, a critical indicator in corneal biomechanics, reflects the cornea's ability to return to its initial shape after undergoing stress. This review aims to provide a comprehensive summary of the corneal elastic modulus, which is a critical biomechanical parameter, and discuss its direct, indirect, and potential measurement methods and clinical applications.
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Affiliation(s)
- Nanqi Shu
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yuxi He
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China
| | - Yan Zhang
- Department of Ophthalmology, The Second Hospital of Jilin University, Changchun, 130041, Jilin Province, China; Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
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Li GY, Feng X, Yun SH. In Vivo Optical Coherence Elastography Unveils Spatial Variation of Human Corneal Stiffness. IEEE Trans Biomed Eng 2024; 71:1418-1429. [PMID: 38032780 PMCID: PMC11086014 DOI: 10.1109/tbme.2023.3338086] [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] [Indexed: 12/02/2023]
Abstract
OBJECTIVE The mechanical properties of corneal tissues play a crucial role in determining corneal shape and have significant implications in vision care. This study aimed to address the challenge of obtaining accurate in vivo data for the human cornea. METHODS We have developed a high-frequency optical coherence elastography (OCE) technique using shear-like antisymmetric (A0)-mode Lamb waves at frequencies above 10 kHz. RESULTS By incorporating an anisotropic, nonlinear constitutive model and utilizing the acoustoelastic theory, we gained quantitative insights into the influence of corneal tension on wave speeds and elastic moduli. Our study revealed significant spatial variations in the shear modulus of the corneal stroma on healthy subjects for the first time. Over an age span from 21 to 34 (N = 6), the central corneas exhibited a mean shear modulus of 87 kPa, while the corneal periphery showed a significant decrease to 44 kPa. The central cornea's shear modulus decreases with age with a slope of -19 +/- 8 kPa per decade, whereas the periphery showed non-significant age dependence. The limbus demonstrated an increased shear modulus exceeding 100 kPa. We obtained wave displacement profiles that are consistent with highly anisotropic corneal tissues. CONCLUSION Our approach enabled precise measurement of corneal tissue elastic moduli in situ with high precision (<7%) and high spatial resolution (<1 mm). Our results revealed significant stiffness variation from the central to peripheral corneas. SIGNIFICANCE The high-frequency OCE technique holds promise for biomechanical evaluation in clinical settings, providing valuable information for refractive surgeries, degenerative disorder diagnoses, and intraocular pressure assessments.
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魏 俊, 陈 鹏, 韩 鹏, 刘 晓, 侯 杰, 武 策, 宋 婕, 陈 维, 李 晓. [Anisotropy and viscoelasticity of different corneal regions in rabbit corneal ectasia model]. SHENG WU YI XUE GONG CHENG XUE ZA ZHI = JOURNAL OF BIOMEDICAL ENGINEERING = SHENGWU YIXUE GONGCHENGXUE ZAZHI 2024; 41:129-135. [PMID: 38403613 PMCID: PMC10894728 DOI: 10.7507/1001-5515.202312022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 12/27/2023] [Indexed: 02/27/2024]
Abstract
The mechanical properties of the cornea in corneal ectasia disease undergo a significant reduction, yet the alterations in mechanical properties within distinct corneal regions remain unclear. In this study, we established a rabbit corneal ectasia model by employing collagenase II to degrade the corneal matrix within a central diameter of 6 mm. Optical coherence tomography was employed for the in vivo assessment of corneal morphology (corneal thickness and corneal curvature) one month after operation. Anisotropy and viscoelastic characteristics of corneal tissue were evaluated through biaxial and uniaxial testing, respectively. The results demonstrated a marked decrease in central corneal thickness, with no significant changes observed in corneal curvature. Under different strains, the elastic modulus of the cornea exhibited no significant differences in the up-down and naso-temporal directions between the control and model groups. However, the cornea in the model group displayed a significantly lower elastic modulus compared to the control group. Specifically, the elastic modulus of the central region cornea in the model group was significantly lower than that of the entire cornea within the same group. Moreover, in comparison to the control group, the cornea in the model group exhibited a significant increase in both creep rate and overall deformation rate. The instantaneous modulus and equilibrium modulus were significantly reduced in the model cornea. No significant differences were observed between the entire cornea and the central cornea concerning these parameters. The results indicate that corneal anisotropy remains unchanged in collagenase-induced ectatic cornea. However, a significant reduction in viscoelastic properties is noticed. This study provides valuable insights for investigating changes in corneal mechanical properties within different regions of ectatic corneal disease.
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Affiliation(s)
- 俊超 魏
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 鹏 陈
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 鹏飞 韩
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 晓娜 刘
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 杰 侯
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 策 武
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 婕 宋
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 维毅 陈
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
| | - 晓娜 李
- 太原理工大学 生物医学工程学院(太原 030024)College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan 030024, P. R. China
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Regnault G, Kirby MA, Wang RK, Shen TT, O’Donnell M, Pelivanov I. Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography. BIOMEDICAL OPTICS EXPRESS 2023; 14:5005-5021. [PMID: 37791258 PMCID: PMC10545180 DOI: 10.1364/boe.497970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 10/05/2023]
Abstract
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (AµT) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from ∼100 µm in the periphery to ∼150 µm in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
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Affiliation(s)
- Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Tueng T. Shen
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
- School of Medicine, University of Washington, Seattle, WA, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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Ross AKM, Schlunck G, Böhringer D, Maier P, Eberwein P, Reinhard T, Lang SJ. Characterization of the Immediate and Delayed Biomechanical Response to UV-A Crosslinking of Human Corneas. Cornea 2023; Publish Ahead of Print:00003226-990000000-00318. [PMID: 37335854 DOI: 10.1097/ico.0000000000003336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/26/2023] [Indexed: 06/21/2023]
Abstract
PURPOSE Keratoconus leads to visual deterioration due to irregular astigmatism and corneal thinning. Riboflavin-based corneal UV-A crosslinking (CXL) induces novel intramolecular and intermolecular links resulting in corneal tissue stiffening, thereby halting disease progression. The purpose of this study was to analyze the immediate and delayed biomechanical responses of human donor corneas to CXL. METHODS CXL was performed according to the Dresden protocol to corneas not suitable for transplantation. Biomechanical properties were subsequently monitored by measuring the Young modulus using nanoindentation. The immediate tissue response was determined after 0, 1, 15, and 30 minutes of irradiation. Delayed biomechanical effects were investigated with follow-up measurements immediately and 1, 3, and 7 days after CXL. RESULTS Young's modulus indicated a linear trend in direct response to increasing irradiation times (mean values: total 61.31 kPa [SD 25.53], 0 minutes 48.82 kPa [SD 19.73], 1 minute 53.44 kPa [SD 25.95], 15 minutes 63.56 kPa [SD 20.99], and 30 minutes 76.76 kPa [SD 24.92]). The linear mixed model for the elastic response of corneal tissue was 49.82 kPa + (0.91 kPa/min × time [minutes]); P < 0.001. The follow-up measurements showed no significant delayed changes in the Young modulus (mean values: total 55,28 kPa [SD 15.95], immediately after CXL 56,83 kPa [SD 18.74], day 1 50.28 kPa [SD 14.15], day 3 57.08 kPa [SD 14.98], and day 7 56.83 kPa [SD 15.07]). CONCLUSIONS This study suggests a linear increase of corneal Young modulus as a function of CXL timing. No significant short-term delayed biomechanical changes posttreatment were observed.
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Affiliation(s)
- Andrea K M Ross
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Günther Schlunck
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Daniel Böhringer
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Philip Maier
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | | | - Thomas Reinhard
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
| | - Stefan Johann Lang
- Eye Center, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and
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Lu X, Jiao H, Shi Y, Li Y, Zhang H, Fu Y, Guo J, Wang Q, Liu X, Zhou M, Ullah MW, Sun J, Liu J. Fabrication of bio-inspired anisotropic structures from biopolymers for biomedical applications: A review. Carbohydr Polym 2023; 308:120669. [PMID: 36813347 DOI: 10.1016/j.carbpol.2023.120669] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 01/25/2023] [Accepted: 02/02/2023] [Indexed: 02/09/2023]
Abstract
The anisotropic features play indispensable roles in regulating various life activities in different organisms. Increasing efforts have been made to learn and mimic various tissues' intrinsic anisotropic structure or functionality for broad applications in different areas, especially in biomedicine and pharmacy. This paper discusses the strategies for fabricating biomaterials using biopolymers for biomedical applications with the case study analysis. Biopolymers, including different polysaccharides, proteins, and their derivates, that have been confirmed with sound biocompatibility for different biomedical applications are summarized, with a special focus on nanocellulose. Advanced analytical techniques for understanding and characterizing the biopolymer-based anisotropic structures for various biomedical applications are also summarized. Challenges still exist in precisely constructing biopolymers-based biomaterials with anisotropic structures from molecular to macroscopic levels and fitting the dynamic processes in native tissue. It is foreseeable that with the advancement of biopolymers' molecular functionalization, biopolymer building block orientation manipulation strategies, and structural characterization techniques, developing anisotropic biopolymer-based biomaterials for different biomedical applications would significantly contribute to a friendly disease-curing and healthcare experience.
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Affiliation(s)
- Xuechu Lu
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Haixin Jiao
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Yifei Shi
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Yan Li
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Hongxing Zhang
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Yinyi Fu
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Jiaqi Guo
- Jiangsu Co-Innovation Center for Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China
| | - Qianqian Wang
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Xiang Liu
- Institute of Medicine & Chemical Engineering, Zhenjiang College, Zhenjiang 212028, China
| | - Mengbo Zhou
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Muhammad Wajid Ullah
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Jianzhong Sun
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China
| | - Jun Liu
- Biofuels Institute, School of the Environment and Safety Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China; Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China.
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7
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Lohmüller R, Böhringer D, Maier PC, Ross AK, Schlunck G, Reinhard T, Lang SJ. [Keratoconus: biomechanics ex vivo]. Klin Monbl Augenheilkd 2023. [PMID: 37146635 DOI: 10.1055/a-2062-3633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
BACKGROUND Keratoconus is associated with an impairment in corneal biomechanics. Using nanoindentation, spatially resolved measurement of biomechanical properties can be performed on corneal tissue. The aim of this study is to assess the biomechanical properties of corneas with keratoconus in comparison to healthy controls. METHODS 17 corneas with keratoconus and 10 healthy corneas unsuitable for transplantation were included in the study. After explantation, corneas were kept in culture medium containing 15% dextran for at least 24 h. Nanoindentation was then performed to a depth of 25 µm at a force increase of 300 µN/min. RESULTS A total of 2328 individual indentations were performed for this study. In the keratoconus group; the mean modulus of elasticity was 23.2 kPa (± 15.0 kPa) for a total of 1802 indentations. In the control group, the mean modulus of elasticity was 48.7 kPa (± 20.5 kPa) with a total of 526 indentations. The Wilcoxon test showed that the differences were statistically significant. CONCLUSION Using nanoindentation, a significantly lower elastic modulus was found in corneas with keratoconus compared to corneas without keratoconus. Further studies are needed to gain a better understanding of how keratoconus affects corneal biomechanics.
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Affiliation(s)
- Robert Lohmüller
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Daniel Böhringer
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Philip Christian Maier
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Andrea Karin Ross
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Günther Schlunck
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Thomas Reinhard
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
| | - Stefan J Lang
- Klinik für Augenheilkunde, Albert-Ludwigs-Universität Freiburg, Medizinische Fakultät, Deutschland
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Lan G, Twa MD, Song C, Feng J, Huang Y, Xu J, Qin J, An L, Wei X. In vivo corneal elastography: A topical review of challenges and opportunities. Comput Struct Biotechnol J 2023; 21:2664-2687. [PMID: 37181662 PMCID: PMC10173410 DOI: 10.1016/j.csbj.2023.04.009] [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: 02/14/2023] [Revised: 04/07/2023] [Accepted: 04/12/2023] [Indexed: 05/16/2023] Open
Abstract
Clinical measurement of corneal biomechanics can aid in the early diagnosis, progression tracking, and treatment evaluation of ocular diseases. Over the past two decades, interdisciplinary collaborations between investigators in optical engineering, analytical biomechanical modeling, and clinical research has expanded our knowledge of corneal biomechanics. These advances have led to innovations in testing methods (ex vivo, and recently, in vivo) across multiple spatial and strain scales. However, in vivo measurement of corneal biomechanics remains a long-standing challenge and is currently an active area of research. Here, we review the existing and emerging approaches for in vivo corneal biomechanics evaluation, which include corneal applanation methods, such as ocular response analyzer (ORA) and corneal visualization Scheimpflug technology (Corvis ST), Brillouin microscopy, and elastography methods, and the emerging field of optical coherence elastography (OCE). We describe the fundamental concepts, analytical methods, and current clinical status for each of these methods. Finally, we discuss open questions for the current state of in vivo biomechanics assessment techniques and requirements for wider use that will further broaden our understanding of corneal biomechanics for the detection and management of ocular diseases, and improve the safety and efficacy of future clinical practice.
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Affiliation(s)
- Gongpu Lan
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Michael D. Twa
- College of Optometry, University of Houston, Houston, TX 77204, United States
| | - Chengjin Song
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
| | - JinPing Feng
- Institute of Engineering and Technology, Hubei University of Science and Technology, Xianning, Hubei 437100, China
| | - Yanping Huang
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jingjiang Xu
- Guangdong-Hong Kong-Macao Intelligent Micro-Nano Optoelectronic Technology Joint Laboratory, School of Physics and Optoelectronic Engineering, Foshan University, Foshan, Guangdong 528000, China
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Jia Qin
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Lin An
- Weiren Meditech Co., Ltd., Foshan, Guangdong 528000, China
| | - Xunbin Wei
- Biomedical Engineering Department, Peking University, Beijing 100081, China
- International Cancer Institute, Peking University, Beijing 100191, China
- Institute of Medical Technology, Peking University Health Science Center, Beijing 100191, China
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Yang S, Zhang J, Tan Y, Wang Y. Unraveling the mechanobiology of cornea: From bench side to the clinic. Front Bioeng Biotechnol 2022; 10:953590. [PMID: 36263359 PMCID: PMC9573972 DOI: 10.3389/fbioe.2022.953590] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 09/06/2022] [Indexed: 11/18/2022] Open
Abstract
The cornea is a transparent, dome-shaped structure on the front part of the eye that serves as a major optic element and a protector from the external environment. Recent evidence shows aberrant alterations of the corneal mechano-environment in development and progression of various corneal diseases. It is, thus, critical to understand how corneal cells sense and respond to mechanical signals in physiological and pathological conditions. In this review, we summarize the corneal mechano-environment and discuss the impact of these mechanical cues on cellular functions from the bench side (in a laboratory research setting). From a clinical perspective, we comprehensively review the mechanical changes of corneal tissue in several cornea-related diseases, including keratoconus, myopia, and keratectasia, following refractive surgery. The findings from the bench side and clinic underscore the involvement of mechanical cues in corneal disorders, which may open a new avenue for development of novel therapeutic strategies by targeting corneal mechanics.
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Affiliation(s)
- Shu Yang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- Department of Ophthalmology, The First People’s Hospital of Huzhou, Huzhou, Zhejiang, China
| | - Jing Zhang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- School of Optometry, Hong Kong Polytechnic University, Hong Kong SAR, China
| | - Youhua Tan
- Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China
- Department of Biomedical Engineering, Hong Kong Polytechnic University, Hong Kong SAR, China
- *Correspondence: Youhua Tan, ; Yan Wang,
| | - Yan Wang
- Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, China
- Tianjin Eye Institute, Tianjin Key Lab of Ophthalmology and Visual Science, Tianjin Eye Hospital, Tianjin, China
- *Correspondence: Youhua Tan, ; Yan Wang,
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10
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Xu Y, Wang C, Yang Y, Liu H, Xiong Z, Zhang T, Sun W. A Multifunctional 3D Bioprinting System for Construction of Complex Tissue Structure Scaffolds: Design and Application. Int J Bioprint 2022; 8:617. [PMID: 36404789 PMCID: PMC9668589 DOI: 10.18063/ijb.v8i4.617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/17/2022] [Indexed: 11/28/2022] Open
Abstract
Three-dimensional (3D) bioprinting offers a potentially powerful new approach to reverse engineering human pathophysiology to address the problem of developing more biomimetic experimental systems. Human tissues and organs are multiscale and multi-material structures. The greatest challenge for organ printing is the complexity of the structural elements, from the shape of the macroscopic structure to the details of the nanostructure. A highly bionic tissue-organ model requires the use of multiple printing processes. Some printers with multiple nozzles and multiple processes are currently reported. However, the bulk volume, which is inconvenient to move, and the high cost of these printing systems limits the expansion of their applications. Scientists urgently need a multifunctional miniaturized 3D bioprinter. In this study, a portable multifunctional 3D bioprinting system was built based on a modular design and a custom written operating application. Using this platform, constructs with detailed surface structures, hollow structures, and multiscale complex tissue analogs were successfully printed using commercial polymers and a series of hydrogel-based inks. With further development, this portable, modular, low-cost, and easy-to-use Bluetooth-enabled 3D printer promises exciting opportunities for resource-constrained application scenarios, not only in biomedical engineering but also in the education field, and may be used in space experiments.
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Affiliation(s)
- Yuanyuan Xu
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
| | - Chengjin Wang
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
| | - Yang Yang
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
| | - Hui Liu
- SunP Boyuan (Beijing) Biotech Co., Ltd., Beijing 100085, China
| | - Zhuo Xiong
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
| | - Ting Zhang
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
| | - Wei Sun
- Biomanufacturing Center, Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
- Biomanufacturing and Rapid Forming Technology Key Laboratory of Beijing, Beijing 100084, China
- Biomanufacturing and Engineering Living Systems” Innovation International Talents Base (111 Base), Beijing 100084, China
- Department of Mechanical Engineering, Drexel University, Philadelphia, PA 19104, USA
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11
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Uyar E, Sarıbaş F. Evaluating Depth and Width of Corneal Wounds Using Anterior Segment Optical Coherence Tomography After Foreign Body Removal. Semin Ophthalmol 2022; 37:774-779. [PMID: 35830289 DOI: 10.1080/08820538.2022.2100712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
PURPOSE To determine corneal foreign body (FB) location together with corneal wound depth and width by using anterior segment optical coherence tomography (AS-OCT) after uncomplicated FB removal. METHOD This prospective study was conducted with patients injured by a superficial metallic corneal FB. Under slit-lamp examination, after determining its location, the FB was removed with a 27-G needle. The depth and width of the corneal wound and the thinnest stromal thickness at the wound site were measured initially using AS-OCT. Measurements were repeated to assess the wound healing process at one week and at two months following FB removal. RESULTS Totally, 63 eyes of 63 patients were included in this study. The average age was 35.8 ± 11.0 years, and 96.8% of the patients were men. In terms of location of the FBs, 26 (41.3%) were in the central region, 21 (33.3%) were in the paracentral region, and 16 (25.4%) were in peripheral regions. The mean depth and width of the corneal wounds were 117.0 ± 42.5 µm and 332.9 ± 99.4 µm, respectively. The mean percentage of corneal wound depth was 18.9 ± 6.1%. In 20 patients who presented for follow-up, it was observed that the width of the wound increased and the thinnest stromal thickness at the wound site decreased over the two months. CONCLUSION The AS-OCT findings of the present study showed that the corneal FBs generally affected the anterior cornea with less than approximately 0.2 mm depth and 0.5 mm width. In addition, FBs were commonly located in the central and paracentral cornea.
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Affiliation(s)
- Enes Uyar
- Department of Ophthalmology, Aksaray Training and Research Hospital, Aksaray University, Aksaray, Turkey
| | - Ferhat Sarıbaş
- Department of Ophthalmology, Aksaray Training and Research Hospital, Aksaray University, Aksaray, Turkey
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12
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Chen Y, Hao Y, Mensah A, Lv P, Wei Q. Bio-inspired hydrogels with fibrous structure: A review on design and biomedical applications. BIOMATERIALS ADVANCES 2022; 136:212799. [PMID: 35929334 DOI: 10.1016/j.bioadv.2022.212799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 04/06/2022] [Accepted: 04/08/2022] [Indexed: 10/18/2022]
Abstract
Numerous tissues in the human body have fibrous structures, including the extracellular matrix, muscles, and heart, which perform critical biological functions and have exceptional mechanical strength. Due to their high-water content, softness, biocompatibility and elastic nature, hydrogels resemble biological tissues. Traditional hydrogels, on the other hand, have weak mechanical properties and lack tissue-like fibrous structures, limiting their potential applications. Thus, bio-inspired hydrogels with fibrous architectures have piqued the curiosity of biomedical researchers. Here, we review fabrication strategies for fibrous hydrogels and their recent progress in the biomedical fields of wound dressings, drug delivery, tissue engineering scaffolds and bioadhesives. Challenges and future perspectives are also discussed.
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Affiliation(s)
- Yajun Chen
- Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China
| | - Yi Hao
- Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China
| | - Alfred Mensah
- Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China
| | - Pengfei Lv
- Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China
| | - Qufu Wei
- Key Laboratory of Eco-textiles, Ministry of Education, Jiangnan University, Wuxi, People's Republic of China.
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13
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Wang Y, Cao H. Corneal and Scleral Biomechanics in Ophthalmic Diseases: An Updated Review. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2022. [DOI: 10.1016/j.medntd.2022.100140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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14
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Li M, Pan G, Zhang H, Guo B. Hydrogel adhesives for generalized wound treatment: Design and applications. JOURNAL OF POLYMER SCIENCE 2022. [DOI: 10.1002/pol.20210916] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Meng Li
- State Key Laboratory for Mechanical Behavior of Materials, and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an China
| | - Guoying Pan
- State Key Laboratory for Mechanical Behavior of Materials, and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an China
| | - Hualei Zhang
- State Key Laboratory for Mechanical Behavior of Materials, and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an China
| | - Baolin Guo
- State Key Laboratory for Mechanical Behavior of Materials, and Frontier Institute of Science and Technology Xi'an Jiaotong University Xi'an China
- Key Laboratory of Shaanxi Province for Craniofacial Precision Medicine Research College of Stomatology, Xi'an Jiaotong University Xi'an China
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15
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Chen S, Jin Z, Zheng G, Ye S, Wang Y, Wang W, Wang Y, Zhu D, Shen M, Lu F. Diurnal variation of corneal elasticity in healthy young human using air-puff optical coherence elastography. JOURNAL OF BIOPHOTONICS 2021; 14:e202000440. [PMID: 33389817 DOI: 10.1002/jbio.202000440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/15/2020] [Accepted: 12/30/2020] [Indexed: 06/12/2023]
Abstract
Due to the disruption of intraocular pressure (IOP) and central corneal thickness (CCT), diurnal variation in normal young human corneal elasticity is not clear. Using the custom-built air-puff optical coherence elastography, one eye of 21 normal subjects is enrolled randomly to measure the central corneal elasticity, IOP, and CCT in different time points within a day. Based on the multi-level model, the corneal elastic modulus is found to have a linear positive relation with IOP (P < .01) but not CCT (P = .175) and time point (P = .174-.686). A new indicator, corneal elasticity change rate, is proposed to present the magnitude of corneal elasticity change caused by 1 mmHg IOP, which can correct the interference effect of IOP. The results show that the corneal elasticity in the normal young human does not have the characteristics of diurnal variation under IOP control. Furthermore, IOP plays an important role in the corneal elasticity, and corneal elasticity change rate can increase the comparability of results between individuals.
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Affiliation(s)
- Sisi Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zi Jin
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
- Department of Biomedical Engineering, College of Engineering, Peking University, Wenzhou, Beijing, China
| | - Gu Zheng
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Shuling Ye
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yiyi Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Weicheng Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yuanyuan Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Dexi Zhu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
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16
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Paterson TE, Dhowre HS, Villanueva D, Holland JW, Reddy Kethiri A, Singh V, Claeyssens F, MacNeil S, Ortega Asencio I. Tuning Electrospun Substrate Stiffness for the Fabrication of a Biomimetic Amniotic Membrane Substitute for Corneal Healing. ACS APPLIED BIO MATERIALS 2021; 4:5638-5649. [DOI: 10.1021/acsabm.1c00436] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Thomas E. Paterson
- Automatic Control and Systems Engineering, University of Sheffield, Sheffield S1 3JD, United Kingdom
| | - Hala S. Dhowre
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Danilo Villanueva
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Joseph W. Holland
- School of Dentistry, University of Sheffield, Sheffield S10 2TA, United Kingdom
| | - Abhinav Reddy Kethiri
- Centre for Ocular Regeneration, Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India
| | - Vivek Singh
- Centre for Ocular Regeneration, Prof. Brien Holden Eye Research Centre, L V Prasad Eye Institute, Hyderabad 500034, India
| | - Frederik Claeyssens
- The Kroto Research Institute, North Campus, University of Sheffield, Sheffield S3 7HQ, United Kingdom
| | - Sheila MacNeil
- The Kroto Research Institute, North Campus, University of Sheffield, Sheffield S3 7HQ, United Kingdom
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17
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Janknecht P. Is it Possible to Derive the Dresdner Correction Formula Using a Finite Element Program? Klin Monbl Augenheilkd 2021; 239:1262-1272. [PMID: 34243213 DOI: 10.1055/a-1478-3833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION The aim was to construct a model cornea by CAD and finite element software to find out how the intraocular pressure compares to the forces for applanation at the outside of the model cornea. These data were to be compared to the Dresdner correction formula. Thereby, it was possible to find out whether the model was plausible and to find hints as to why a correction for how the intraocular pressure depends on the corneal thickness is necessary at all. METHODS Using the open-source software FreeCad and geometrical data for the cornea of the literature, an average cornea was constructed. On this average cornea, a finite element analysis was performed using the free software z88aurora. The intraocular pressure was measured by applanation of the outer cornea. The necessary forces were analysed. RESULTS In this model, the intraocular pressure had to be corrected depending on the corneal thickness. The correction factor was kmean; finite elements = 19.17 - 0.0334*corneal thickness. The necessary correction did not exclusively depend on the relation between the endothelial area and the area of the outer cornea: for this relation alone the correction would have been karea-relation = 1.0361 - 0.0006*corneal thickness. DISCUSSION The model correction formula was close to the Dresdner formula. The relation between endothelial area and the area of the outer cornea could only explain about half of the necessary correction.
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18
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Napoli PE, Nioi M, d'Aloja E, Loy F, Fossarello M. The architecture of corneal stromal striae on optical coherence tomography and histology in an animal model and in humans. Sci Rep 2020; 10:19861. [PMID: 33199775 PMCID: PMC7670407 DOI: 10.1038/s41598-020-76963-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 11/04/2020] [Indexed: 12/13/2022] Open
Abstract
The purpose of this study was to use a portable optical coherence tomography (OCT) for characterization of corneal stromal striae (CSS) in an ovine animal model and human corneas with histological correlation, in order to evaluate their architectural pattern by image analysis. Forty-six eyes from female adult sheep (older than 2 years), and 12 human corneas, were included in our study. The eyes were examined in situ by a portable OCT, without enucleation. All OCT scans were performed immediately after death, and then the eyes were delivered to a qualified histology laboratory. In the ovine animal model, CSS were detected with OCT in 89.1% (41/46) of individual scans and in 93.4% (43/46) of histological slices. In human corneas, CSS were found in 58.3% (7/12) of cases. In both corneal types, CSS appeared as "V"- or "X"-shaped structures, with very similar angle values of 70.8° ± 4° on OCT images and 71° ± 4° on histological slices (p ≤ 0.01). Data analysis demonstrated an excellent degree of reproducibility and inter-rater reliability of measurements (p < 0.001). The present study demonstrated that by using a portable OCT device, CSS can be visualized in ovine and human corneas. This finding suggests their generalized presence in various mammals. The frequent observation, close to 60%, of such collagen texture in the corneal stroma, similar to a 'truss bridge' design, permits to presume that it plays an important structural role, aimed to distribute tensile and compressive forces in various directions, conferring resilience properties to the cornea.
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Affiliation(s)
- Pietro Emanuele Napoli
- San Giovanni di Dio Hospital, Clinica Oculistica, Azienda Ospedaliera Universitaria di Cagliari, via Ospedale 46, 09124, Cagliari, Italy.
- Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy.
| | - Matteo Nioi
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Ernesto d'Aloja
- Department of Medical Sciences and Public Health, University of Cagliari, Cagliari, Italy
| | - Francesco Loy
- Department of Biomedical Sciences, Section of Cytomorphology, University of Cagliari, Cagliari, Italy
| | - Maurizio Fossarello
- San Giovanni di Dio Hospital, Clinica Oculistica, Azienda Ospedaliera Universitaria di Cagliari, via Ospedale 46, 09124, Cagliari, Italy
- Department of Surgical Sciences, Eye Clinic, University of Cagliari, Cagliari, Italy
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19
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McKay TB, Hutcheon AEK, Guo X, Zieske JD, Karamichos D. Modeling the cornea in 3-dimensions: Current and future perspectives. Exp Eye Res 2020; 197:108127. [PMID: 32619578 PMCID: PMC8116933 DOI: 10.1016/j.exer.2020.108127] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/17/2020] [Accepted: 06/23/2020] [Indexed: 02/08/2023]
Abstract
The cornea is an avascular, transparent ocular tissue that serves as a refractive and protective structure for the eye. Over 90% of the cornea is composed of a collagenous-rich extracellular matrix within the stroma with the other 10% composed by the corneal epithelium and endothelium layers and their corresponding supporting collagen layers (e.g., Bowman's and Descemet's membranes) at the anterior and posterior cornea, respectively. Due to its prominent role in corneal structure, tissue engineering approaches to model the human cornea in vitro have focused heavily on the cellular and functional properties of the corneal stroma. In this review, we discuss model development in the context of culture dimensionality (e.g., 2-dimensional versus 3-dimensional) and expand on the optical, biomechanical, and cellular functions promoted by the culture microenvironment. We describe current methods to model the human cornea with focus on organotypic approaches, compressed collagen, bioprinting, and self-assembled stromal models. We also expand on co-culture applications with the inclusion of relevant corneal cell types, such as epithelial, stromal keratocyte or fibroblast, endothelial, and neuronal cells. Further advancements in corneal tissue model development will markedly improve our current understanding of corneal wound healing and regeneration.
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Affiliation(s)
- Tina B McKay
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, 02114, USA
| | - Audrey E K Hutcheon
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, 02114, USA
| | - Xiaoqing Guo
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, 02114, USA
| | - James D Zieske
- Schepens Eye Research Institute of Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA, 02114, USA
| | - Dimitrios Karamichos
- North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmaceutical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA; Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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20
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Jin Z, Chen S, Dai Y, Bao C, Ye S, Zhou Y, Wang Y, Huang S, Wang Y, Shen M, Zhu D, Lu F. In vivo noninvasive measurement of spatially resolved corneal elasticity in human eyes using Lamb wave optical coherence elastography. JOURNAL OF BIOPHOTONICS 2020; 13:e202000104. [PMID: 32368840 DOI: 10.1002/jbio.202000104] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 05/23/2023]
Abstract
Current elastography techniques are limited in application to accurately assess spatially resolved corneal elasticity in vivo for human eyes. The air-puff optical coherence elastography (OCE) with an eye motion artifacts correction algorithm is developed to distinguish the in vivo cornea vibration from the eye motion and visualize the Lamb wave propagation clearly in healthy subjects. Based on the Lamb wave model, the phase velocity dispersion curve in the high-frequency is calculated to obtain spatially resolved corneal elasticity accurately with high repeatability. It is found that the corneal elasticity has regional variations and is correlated with intraocular pressure, which suggests that the method has the potential to provide noninvasive measurement of spatially resolved corneal elasticity in clinical practice.
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Affiliation(s)
- Zi Jin
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Sisi Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yingying Dai
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Chenhong Bao
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Shuling Ye
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yuheng Zhou
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yiyi Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Shenghai Huang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Yuanyuan Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Dexi Zhu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Zhejiang, China
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21
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Ashofteh Yazdi A, Melchor J, Torres J, Faris I, Callejas A, Gonzalez-Andrades M, Rus G. Characterization of non-linear mechanical behavior of the cornea. Sci Rep 2020; 10:11549. [PMID: 32665558 PMCID: PMC7360609 DOI: 10.1038/s41598-020-68391-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 06/23/2020] [Indexed: 11/24/2022] Open
Abstract
The objective of this study was to evaluate which hyperelastic model could best describe the non-linear mechanical behavior of the cornea, in order to characterize the capability of the non-linear model parameters to discriminate structural changes in a damaged cornea. Porcine corneas were used, establishing two different groups: control (non-treated) and NaOH-treated (damaged) corneas (n = 8). NaOH causes a chemical burn to the corneal tissue, simulating a disease associated to structural damage of the stromal layer. Quasi-static uniaxial tensile tests were performed in nasal-temporal direction immediately after preparing corneal strips from the two groups. Three non-linear hyperelastic models (i.e. Hamilton-Zabolotskaya model, Ogden model and Mooney-Rivlin model) were fitted to the stress–strain curves obtained in the tensile tests and statistically compared. The corneas from the two groups showed a non-linear mechanical behavior that was best described by the Hamilton-Zabolotskaya model, obtaining the highest coefficient of determination (R2 > 0.95). Moreover, Hamilton-Zabolotskaya model showed the highest discriminative capability of the non-linear model parameter (Parameter A) for the tissue structural changes between the two sample groups (p = 0.0005). The present work determines the best hyperelastic model with the highest discriminative capability in description of the non-linear mechanical behavior of the cornea.
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Affiliation(s)
- A Ashofteh Yazdi
- Ultrasonics Lab, Department of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071, Granada, Spain.,Department of Biomedical Engineering, Islamic Azad University, Mashhad Branch, Mashhad, Iran
| | - J Melchor
- Department of Statistics and Operations Research, University of Granada, Granada, Spain.,Instituto de Investigación Biosanitaria, Ibs.GRANADA, Granada, Spain.,Excellence Research Unit, "Modelling Nature" (MNat), University of Granada, Granada, Spain
| | - J Torres
- Ultrasonics Lab, Department of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071, Granada, Spain.,Instituto de Investigación Biosanitaria, Ibs.GRANADA, Granada, Spain
| | - I Faris
- Ultrasonics Lab, Department of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071, Granada, Spain.,Instituto de Investigación Biosanitaria, Ibs.GRANADA, Granada, Spain
| | - A Callejas
- Ultrasonics Lab, Department of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071, Granada, Spain.,Instituto de Investigación Biosanitaria, Ibs.GRANADA, Granada, Spain
| | - M Gonzalez-Andrades
- Maimonides Biomedical Research Institute of Cordoba (IMIBIC), Department of Ophthalmology, Reina Sofia University Hospital and University of Cordoba, Edificio IMIBIC, Av. Menéndez Pidal, s/n. 14004, Cordoba, Spain. .,Massachusetts Eye and Ear and Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA, USA.
| | - G Rus
- Ultrasonics Lab, Department of Structural Mechanics, University of Granada, Politécnico de Fuentenueva, 18071, Granada, Spain. .,Instituto de Investigación Biosanitaria, Ibs.GRANADA, Granada, Spain. .,Excellence Research Unit, "Modelling Nature" (MNat), University of Granada, Granada, Spain.
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22
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Characterization of hyperelastic mechanical properties for youth corneal anterior central stroma based on collagen fibril crimping constitutive model. J Mech Behav Biomed Mater 2020; 103:103575. [DOI: 10.1016/j.jmbbm.2019.103575] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 11/03/2019] [Accepted: 11/29/2019] [Indexed: 11/19/2022]
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23
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McKay TB, Priyadarsini S, Karamichos D. Mechanisms of Collagen Crosslinking in Diabetes and Keratoconus. Cells 2019; 8:cells8101239. [PMID: 31614631 PMCID: PMC6830090 DOI: 10.3390/cells8101239] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/09/2019] [Accepted: 10/10/2019] [Indexed: 12/14/2022] Open
Abstract
Collagen crosslinking provides the mechanical strength required for physiological maintenance of the extracellular matrix in most tissues in the human body, including the cornea. Aging and diabetes mellitus (DM) are processes that are both associated with increased collagen crosslinking that leads to increased corneal rigidity. By contrast, keratoconus (KC) is a corneal thinning disease associated with decreased mechanical stiffness leading to ectasia of the central cornea. Studies have suggested that crosslinking mediated by reactive advanced glycation end products during DM may protect the cornea from KC development. Parallel to this hypothesis, riboflavin-mediated photoreactive corneal crosslinking has been proposed as a therapeutic option to halt the progression of corneal thinning by inducing intra- and intermolecular crosslink formation within the collagen fibrils of the stroma, leading to stabilization of the disease. Here, we review the pathobiology of DM and KC in the context of corneal structure, the epidemiology behind the inverse correlation of DM and KC development, and the chemical mechanisms of lysyl oxidase-mediated crosslinking, advanced glycation end product-mediated crosslinking, and photoreactive riboflavin-mediated corneal crosslinking. The goal of this review is to define the biological and chemical pathways important in physiological and pathological processes related to collagen crosslinking in DM and KC.
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Affiliation(s)
- Tina B McKay
- Schepens Eye Research Institute/Massachusetts Eye and Ear, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA.
| | - Shrestha Priyadarsini
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
| | - Dimitrios Karamichos
- Department of Ophthalmology/Dean McGee Eye Institute, University of Oklahoma Health Science Center, Oklahoma City, OK 73104, USA.
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24
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Blackburn BJ, Jenkins MW, Rollins AM, Dupps WJ. A Review of Structural and Biomechanical Changes in the Cornea in Aging, Disease, and Photochemical Crosslinking. Front Bioeng Biotechnol 2019; 7:66. [PMID: 31019909 PMCID: PMC6459081 DOI: 10.3389/fbioe.2019.00066] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/07/2019] [Indexed: 12/27/2022] Open
Abstract
The study of corneal biomechanics is motivated by the tight relationship between biomechanical properties and visual function within the ocular system. For instance, variation in collagen fibril alignment and non-enzymatic crosslinks rank high among structural factors which give rise to the cornea's particular shape and ability to properly focus light. Gradation in these and other factors engender biomechanical changes which can be quantified by a wide variety of techniques. This review summarizes what is known about both the changes in corneal structure and associated changes in corneal biomechanical properties in aging, keratoconic, and photochemically crosslinked corneas. In addition, methods for measuring corneal biomechanics are discussed and the topics are related to both clinical studies and biomechanical modeling simulations.
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Affiliation(s)
- Brecken J. Blackburn
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - Michael W. Jenkins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH, United States
| | - Andrew M. Rollins
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
| | - William J. Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States
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De Stefano VS, Ford MR, Seven I, Dupps WJ. Live human assessment of depth-dependent corneal displacements with swept-source optical coherence elastography. PLoS One 2018; 13:e0209480. [PMID: 30592752 PMCID: PMC6310362 DOI: 10.1371/journal.pone.0209480] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 12/06/2018] [Indexed: 01/01/2023] Open
Abstract
Purpose To assess depth-dependent corneal displacements in live normal subjects using optical coherence elastography (OCE). Methods A corneal elastography method based on swept-source optical coherence tomography (OCT) was implemented in a clinical prototype. Low amplitude corneal deformation was produced during OCT imaging with a linear actuator-driven lens coupled to force transducers. A cross-correlation algorithm was applied to track frame-by-frame speckle displacement across horizontal meridian scans. Intra-measurement force and displacement data series were plotted against each other to produce local axial stiffness approximations, k, defined by the slope of a linear fit to the force/displacement data (ignoring non-axial contributions from corneal bending). Elastographic maps displaying local k values across the cornea were generated, and the ratio of mean axial stiffness approximations for adjacent anterior and posterior stromal regions, ka/kp, was calculated. Intraclass correlation coefficients (ICC) were used to estimate repeatability. Results Seventeen eyes (ten subjects) were included in this prospective first-in-humans translational study. The ICC was 0.84. Graphs of force vs. displacement demonstrated that, for simultaneously acquired measurements involving the same applied force, anterior stromal displacements were lower (suggesting stiffer behavior) than posterior stromal displacements. Mean ka was 0.016±0.004 g/mm and mean kp was 0.014±0.004 g/mm, giving a mean ka/kp ratio of 1.123±0.062. Conclusion OCE is a clinically feasible, non-invasive corneal biomechanical characterization method capable of resolving depth-dependent differences in corneal deformation behavior. The anterior stroma demonstrated responses consistent with stiffer properties in compression than the posterior stroma, but to a degree that varied across normal eyes. The clinical capability to measure these differences has implications for assessing the biomechanical impact of corneal refractive surgeries and for ectasia risk screening applications.
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Affiliation(s)
- Vinicius S. De Stefano
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Ophthalmology and Visual Sciences, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Matthew R. Ford
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - Ibrahim Seven
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
| | - William J. Dupps
- Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States of America
- Dept. of Ophthalmology, Cleveland Clinic Lerner College of Medicine of CWRU, Cleveland, OH, United States of America
- * E-mail:
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Seiler TG, Shao P, Frueh BE, Yun SH, Seiler T. The influence of hydration on different mechanical moduli of the cornea. Graefes Arch Clin Exp Ophthalmol 2018; 256:1653-1660. [PMID: 30043266 DOI: 10.1007/s00417-018-4069-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 06/13/2018] [Accepted: 07/12/2018] [Indexed: 11/28/2022] Open
Abstract
PURPOSE To determine the interrelation of different elastic moduli of the cornea and to investigate their dependency on corneal hydration. METHODS Rabbit eyes were divided into four groups. Corneas were excised and mounted into a Barron artificial anterior chamber. Various corneal hydration steady states were achieved with different dextran T-500 concentrations in the anterior chamber, as well as on the corneal anterior surface. The treatment-solutions of each group contained either 5, 10, 15, or 20% w/w dextran. Ultrasound pachymetry was used to measure central corneal thickness. Brillouin microscopy of the central cornea determined the longitudinal bulk modulus by means of Brillouin frequency shift. Subsequently, a 5-mm-wide central strip was taken for extensiometry to measure the tangential elastic modulus. RESULTS The longitudinal bulk modulus was 1.2-times higher in corneas dehydrated with 20% dextran compared to those hydrated with 5% dextran. In contrast, the tangential elastic modulus increased by 4.4 times. The obtained longitudinal bulk moduli were two orders of magnitude bigger than the tangential elastic moduli. Regression analysis of longitudinal bulk modulus and tangential elastic modulus revealed a quadratic relation. The bulk modulus seemed to be independent of tension, whereas the elastic modulus was tension-dependent. Greater corneal hydration led to significantly thicker pachymetry. CONCLUSION Corneal biomechanics are highly dependent on the level of corneal hydration. Surprisingly, tangential elastic moduli were more sensitive to hydration changes than longitudinal bulk moduli. A quadratic relation was found between both moduli.
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Affiliation(s)
- Theo G Seiler
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Harvard University, 50 Blossom Street, Boston, MA, 02114, USA. .,Universitätsklinik für Augenheilkunde, Inselspital, 3010, Bern, Switzerland. .,Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Stockerstrasse 37, 8002 Zürich, Switzerland, .
| | - Peng Shao
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Harvard University, 50 Blossom Street, Boston, MA, 02114, USA
| | - Beatrice E Frueh
- Universitätsklinik für Augenheilkunde, Inselspital, 3010, Bern, Switzerland
| | - Seok-Hyun Yun
- Wellman Center for Photomedicine - Massachusetts General Hospital, Harvard Medical School, Harvard University, 50 Blossom Street, Boston, MA, 02114, USA
| | - Theo Seiler
- Institut für Refraktive und Ophthalmo-Chirurgie (IROC), Stockerstrasse 37, 8002 Zürich, Switzerland
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Kojima T, Takagi M, Ichikawa K, Horai R, Sakai Y, Tanaka Y, Tamaoki A, Ichikawa K. Clinical and ex vivo laboratory comparison of the self-sealing properties and dimensional stability between the femtosecond laser and manual clear corneal incisions. Acta Ophthalmol 2018; 96:e510-e514. [PMID: 29193782 DOI: 10.1111/aos.13634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 10/12/2017] [Indexed: 11/28/2022]
Abstract
PURPOSE To compare the self-sealing features and dimensional stability between the femtosecond laser (FL) and manual knife corneal incision. METHODS For the clinical study, 29 consecutive eyes from 29 patients and 28 eyes from 28 patients who underwent cataract surgery with FL corneal incision and manual knife incision, respectively, were enrolled. Immediately after cataract surgery, the self-sealing features of the corneal incisions were evaluated. Scanning electron microscopy (SEM) images were obtained. For the experimental study, clear corneal incisions with a knife or FL with different energy settings (3, 6 and 9 μJ) were created in fresh porcine eyes, followed by a stress test. The incision width was measured before and after the stress test. RESULTS In the clinical study, the knife group had a higher self-sealing score (0.60 ± 0.49 points) than the FL group (0.17 ± 0.38 points). In the experimental study, the deformation rate in the knife incision (5.04 ± 1.93) was significantly lower than that in the FL with any energy. The deformation rate in the 9 μJ (12.98 ± 2.76) was significantly higher than in the 3 μJ (8.54 ± 2.38) and 6 μJ (8.82 ± 2.85) FL energies. Scanning electron microscopy (SEM) images revealed that the corneal stromal surface of the knife incision was smoother than that of the FL. Higher energy FL showed more irregular surfaces. CONCLUSION Higher FL energy tended to widen a clear corneal incision when mechanical stress was applied. The histological differences at the inner tunnel surface may cause differences in wound stability of the corneal incision.
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Affiliation(s)
- Takashi Kojima
- Department of Ophthalmology; Japanese Red Cross Gifu Hospital; Gifu Japan
| | - Mari Takagi
- Department of Ophthalmology; Japanese Red Cross Gifu Hospital; Gifu Japan
| | - Kei Ichikawa
- Department of Ophthalmology; Japanese Red Cross Gifu Hospital; Gifu Japan
| | - Rie Horai
- Chukyo Medical, CO., INC.; Nagoya Japan
| | | | | | - Akeno Tamaoki
- Department of Ophthalmology; Japan Community Healthcare Organization Chukyo Hospital; Nagoya Japan
- Shinshu University Interdisciplinary Graduate School of Science and Technology; Nagano Japan
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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: 22] [Impact Index Per Article: 3.7] [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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Evolution of the vertebrate corneal stroma. Prog Retin Eye Res 2018; 64:65-76. [DOI: 10.1016/j.preteyeres.2018.01.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 01/12/2018] [Accepted: 01/15/2018] [Indexed: 12/14/2022]
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Nohava J, Swain M, Lang SJ, Maier P, Heinzelmann S, Reinhard T, Eberwein P. Instrumented indentation for determination of mechanical properties of human cornea after ultraviolet-A crosslinking. J Biomed Mater Res A 2018; 106:1413-1420. [DOI: 10.1002/jbm.a.36337] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Revised: 12/13/2017] [Accepted: 12/21/2017] [Indexed: 01/07/2023]
Affiliation(s)
- Jiri Nohava
- Anton Paar TriTec, Rue de la Gare 4; Peseux CH-2034 Switzerland
| | - Michael Swain
- Biomaterials Faculty of Dentistry; The University of Sydney; Sydney NSW 2009 Australia
- Faculty of Dentistry; The University of Kuwait; Safah 13110 Kuwait
| | - Stefan J. Lang
- Eye Center, Medical Center, Faculty of Medicine; University of Freiburg; Freiburg 79110 Germany
| | - Philip Maier
- Eye Center, Medical Center, Faculty of Medicine; University of Freiburg; Freiburg 79110 Germany
| | - Sonja Heinzelmann
- Eye Center, Medical Center, Faculty of Medicine; University of Freiburg; Freiburg 79110 Germany
| | - Thomas Reinhard
- Eye Center, Medical Center, Faculty of Medicine; University of Freiburg; Freiburg 79110 Germany
| | - Philipp Eberwein
- Eye Center, Medical Center, Faculty of Medicine; University of Freiburg; Freiburg 79110 Germany
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Zhao Z, Fang R, Rong Q, Liu M. Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1703045. [PMID: 29059482 DOI: 10.1002/adma.201703045] [Citation(s) in RCA: 170] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 07/06/2017] [Indexed: 06/07/2023]
Abstract
In the human body, many soft tissues with hierarchically ordered composite structures, such as cartilage, skeletal muscle, the corneas, and blood vessels, exhibit highly anisotropic mechanical strength and functionality to adapt to complex environments. In artificial soft materials, hydrogels are analogous to these biological soft tissues due to their "soft and wet" properties, their biocompatibility, and their elastic performance. However, conventional hydrogel materials with unordered homogeneous structures inevitably lack high mechanical properties and anisotropic functional performances; thus, their further application is limited. Inspired by biological soft tissues with well-ordered structures, researchers have increasingly investigated highly ordered nanocomposite hydrogels as functional biological engineering soft materials with unique mechanical, optical, and biological properties. These hydrogels incorporate long-range ordered nanocomposite structures within hydrogel network matrixes. Here, the critical design criteria and the state-of-the-art fabrication strategies of nanocomposite hydrogels with highly ordered structures are systemically reviewed. Then, recent progress in applications in the fields of soft actuators, tissue engineering, and sensors is highlighted. The future development and prospective application of highly ordered nanocomposite hydrogels are also discussed.
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Affiliation(s)
- Ziguang Zhao
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
| | - Ruochen Fang
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
| | - Qinfeng Rong
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
| | - Mingjie Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, 100191, P. R. China
- International Research Institute for Multidisciplinary Science, Beihang University, Beijing, 100191, P. R. China
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