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Zu H, Zhang K, Zhang H, Qian X. An Inverse Method to Determine Mechanical Parameters of Porcine Vitreous Bodies Based on the Indentation Test. Bioengineering (Basel) 2023; 10:646. [PMID: 37370577 DOI: 10.3390/bioengineering10060646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
The vitreous body keeps the lens and retina in place and protects these tissues from physical insults. Existing studies have reported that the mechanical properties of vitreous body varied after liquefaction, suggesting mechanical properties could be effective parameters to identify vitreous liquefaction process. Thus, in this work, we aimed to propose a method to determine the mechanical properties of vitreous bodies. Fresh porcine eyes were divided into three groups, including the untreated group, the 24 h liquefaction group and the 48 h liquefaction group, which was injected collagenase and then kept for 24 h or 48 h. The indentation tests were carried out on the vitreous body in its natural location while the posterior segment of the eye was fixed in the container. A finite element model of a specimen undertaking indentation was constructed to simulate the indentation test with surface tension of vitreous body considered. Using the inverse method, the mechanical parameters of the vitreous body and the surface tension coefficient were determined. For the same parameter, values were highest in the untreated group, followed by the 24 h liquefaction group and the lowest in the 48 h liquefaction group. For C10 in the neo-Hookean model, the significant differences were found between the untreated group and liquefaction groups. This work quantified vitreous body mechanical properties successfully using inverse method, which provides a new method for identifying vitreous liquefactions related studies.
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Affiliation(s)
- Haicheng Zu
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
| | - Kunya Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
| | - Haixia Zhang
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
| | - Xiuqing Qian
- School of Biomedical Engineering, Capital Medical University, Beijing 100069, China
- Beijing Key Laboratory of Fundamental Research on Biomechanics in Clinical Application, Capital Medical University, Beijing 100069, China
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Chen D, Liu X, Geng X, Huo H, Dong Y, Tang M, Tang Z, Qiao X, Fan Y. A simple indentation technique for identifying localized liquefaction of the vitreous body. J Biomech 2021; 129:110795. [PMID: 34662756 DOI: 10.1016/j.jbiomech.2021.110795] [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: 07/13/2021] [Revised: 09/17/2021] [Accepted: 10/04/2021] [Indexed: 11/16/2022]
Abstract
Identification of vitreous liquefaction (VL) is important for investigating some eye pathologies related to changes in the mechanical properties of the vitreous, such as posterior vitreous detachment or retinal detachment. However, because of the extremely high-water content, characterization of the structural and mechanical properties of the vitreous remains a challenge. In the current study, a simple indentation test was performed on the fresh vitreous, partially liquefied vitreous and water, using a mechanical testing machine with a high-precision load cell. Pressure loads on the indenter changing with time for different samples were obtained to characterize their mechanical properties. VL identification was achieved based on a comparison of relative differences in some typical mechanical parameters (e.g. the pressure at the moment of the insertion (P0), the pressure at the steady mechanical state (P∞) and the time when the pressure on the indenter declined to one half the initial value (t1/2)) between 1) partially liquefied vitreous and fresh vitreous samples and 2) partially liquefied vitreous and water samples. The results indicated that P0 of the partially liquefied vitreous was almost half that of fresh vitreous (p < 0.05) and approximately 1.5 times that of water (p < 0.05). t1/2 of the partially liquefied vitreous was approximately 1.4 times higher than that of fresh vitreous (p < 0.05) and approximately 80% of that of water (p < 0.05). It is concluded that P0 and t1/2 can be used as indicators to identify localized liquefaction of the vitreous.
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Affiliation(s)
- Duo Chen
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaoyu Liu
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; School of Medical Science and Engineering Medicine, Beihang University, Beijing 100083, China.
| | - Xiaoqi Geng
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Hongqiang Huo
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Ying Dong
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Min Tang
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Zhili Tang
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Xiaofeng Qiao
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Yubo Fan
- Key Laboratory of Biomechanics and Mechanobiology, Ministry of Education, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China; School of Medical Science and Engineering Medicine, Beihang University, Beijing 100083, China; State Key Laboratory of Virtual Reality Technology and Systems, Beihang University, Beijing 100083, China.
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Kim S, Moon S, Rho S, Yoon S. Measurements of acoustic radiation force of ultrahigh frequency ultrasonic transducers using model-based approach. APPLIED PHYSICS LETTERS 2021; 118:184102. [PMID: 33981116 PMCID: PMC8096457 DOI: 10.1063/5.0044512] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 04/19/2021] [Indexed: 05/13/2023]
Abstract
Even though ultrahigh frequency ultrasonic transducers over 60 MHz have been used for single-cell-level manipulation such as intracellular delivery, acoustic tweezers, and stimulation to investigate cell phenotype and cell mechanics, no techniques have been available to measure the actual acoustic radiation force (ARF) applied to target cells. Therefore, we have developed an approach to measure the ARF of ultrahigh frequency ultrasonic transducers using a theoretical model of the dynamics of a solid sphere in a gelatin phantom. To estimate ARF at the focus of a 130 MHz transducer, we matched measured maximum displacements of a solid sphere with theoretical calculations. We selected appropriate ranges of input voltages and pulse durations for single-cell applications, and the estimated ARF was in the range of tens of μN. To gauge the influence of pulse duration, an impulse of different pulse durations was estimated. Fluorescence resonance energy transfer live cell imaging was demonstrated to visualize calcium transport between cells after a target single cell was stimulated by the developed ultrasonic transducer.
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Affiliation(s)
| | | | | | - Sangpil Yoon
- Author to whom correspondence should be addressed: . Tel.: +1-514-631‐6510
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Aboulatta A, Abass A, Makarem A, Eliasy A, Zhou D, Chen D, Liu X, Elsheikh A. Experimental evaluation of the viscoelasticity of porcine vitreous. J R Soc Interface 2021; 18:20200849. [PMID: 33530856 DOI: 10.1098/rsif.2020.0849] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study aims to estimate the material properties of the porcine vitreous while testing it in close to its natural physiological conditions. Eighteen porcine eyes were tested within 48 h post-mortem. A custom-built computer-controlled test rig was designed to support, load and monitor the behaviour of eye globes while being subjected to dynamic rotation cycles mimicking saccade eye movement. Specimens were glued to the base of a container, surrounded by gelatin, frozen and cut in half to expose the vitreous. After thawing, the container was subjected to concentric dynamic rotations of up to 5°, 10° or 15°, while taking 50 MP photos of the specimen every 2 ms. The images were analysed by a digital image correlation algorithm to trace the movement of marked points on the vitreous surface with different radii from the centre of the posterior chamber. The initial camera image was used in building a finite-element model of the test set-up, which was used in an inverse analysis exercise to estimate the material properties of the vitreous. Angular displacements of the monitored points were up to 3.3°, 4.1° and 3.9° in response to eye rotations of 5°, 10° and 15°, respectively. With the experimental relationships between eye rotation and angular displacements used as target behaviour, the inverse analysis exercise estimated the initial shear modulus, the long-term shear modulus and the viscoelastic decay constant of the porcine vitreous as 2.10 ± 0.15 Pa, 0.50 ± 0.04 Pa and 1.20 ± 0.09 s-1, respectively. Consideration of the viscoelasticity of the vitreous was essential to represent its experimental behaviour. Testing the vitreous in close to its normal physiological conditions produced estimations of the initial shear modulus and long-term shear modulus that were, respectively, smaller and larger than reported values (Zimberlin et al. 2010 Soft Matter 6, 3632-3635. (doi:10.1039/b925407b), Liu et al. 2013 J. Biomech. 46, 1321-7. (doi:10.1016/j.jbiomech.2013.02.006), Rossi et al. 2011 Invest. Ophthalmol. Vis. Sci. 52, 3994-4002. (doi:10.1167/iovs.10-6477)).
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Affiliation(s)
- Ali Aboulatta
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ahmed Makarem
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Dong Zhou
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK
| | - Duo Chen
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, People's Republic of China
| | - Xiaoyu Liu
- Key Laboratory for Biomechanics and Mechanobiology of the Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, People's Republic of China.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, People's Republic of China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool L69 3GH, UK.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, People's Republic of China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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Tram NK, Maxwell CJ, Swindle-Reilly KE. Macro- and Microscale Properties of the Vitreous Humor to Inform Substitute Design and Intravitreal Biotransport. Curr Eye Res 2020; 46:429-444. [PMID: 33040616 DOI: 10.1080/02713683.2020.1826977] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Research on the vitreous humor and development of hydrogel vitreous substitutes have gained a rapid increase in interest within the past two decades. However, the properties of the vitreous humor and vitreous substitutes have yet to be consolidated. In this paper, the mechanical properties of the vitreous humor and hydrogel vitreous substitutes were systematically reviewed. The number of publications on the vitreous humor and vitreous substitutes over the years, as well as their respective testing conditions and testing techniques were analyzed. The mechanical properties of the human vitreous were found to be most similar to the vitreous of pigs and rabbits. The storage and loss moduli of the hydrogel vitreous substitutes developed were found to be orders of magnitude higher in comparison to the native human vitreous. However, the reported modulus for human vitreous, which was most commonly tested in vitro, has been hypothesized to be different in vivo. Future studies should focus on testing the mechanical properties of the vitreous in situ or in vivo. In addition to its mechanical properties, the vitreous humor has other biotransport mechanisms and biochemical functions that establish a redox balance and maintain an oxygen gradient inside the vitreous chamber to protect intraocular tissues from oxidative damage. Biomimetic hydrogel vitreous substitutes have the potential to provide ophthalmologists with additional avenues for treating and controlling vitreoretinal diseases while preventing complications after vitrectomy. Due to the proximity and interconnectedness of the vitreous humor to other ocular tissues, particularly the lens and the retina, more interest has been placed on understanding the properties of the vitreous humor in recent years. A better understanding of the properties of the vitreous humor will aid in improving the design of biomimetic vitreous substitutes and enhancing intravitreal biotransport.
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Affiliation(s)
- Nguyen K Tram
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Courtney J Maxwell
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
| | - Katelyn E Swindle-Reilly
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA.,William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH, USA.,Department of Ophthalmology & Visual Science, The Ohio State University, Columbus, OH, USA
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Agladioglu K, Pekel G, Altintas Kasikci S, Yagci R, Kiroglu Y. An evaluation of ocular elasticity using real-time ultrasound elastography in primary open-angle glaucoma. Br J Radiol 2016; 89:20150429. [PMID: 26838949 DOI: 10.1259/bjr.20150429] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE The aim of this study was to compare sonoelastographic findings in the retina-choroid-sclera (RCS) complex and vitreous in glaucomatous and healthy eyes. METHODS For this cross-sectional comparative study, 20 patients with primary open-angle glaucoma and 20 healthy volunteers were recruited. Ultrasound elastography measurements were taken with a sonographic scanner of the RCS complex, anterior vitreous (AV), posterior vitreous (PV), retrobulbar fat tissue (RFT), optic disc (OD) and optic nerve (ON) in each eye. RESULTS The elasticity index of the RCS complex, RFT, OD, ON, AV and PV was similar in both groups (p > 0.05), although the AV/PV strain ratio in the group of patients with glaucoma was significantly higher (p = 0.04). CONCLUSION Glaucoma increases the AV/PV strain ratio. In providing reproducible and consistent values, the real-time elastography (RTE) technique may be helpful in elucidating the mechanisms of glaucoma in some aspects. ADVANCES IN KNOWLEDGE This study can help to evaluate the elasticity of the RCS complex and vitreous in glaucomatous eyes with RTE.
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Affiliation(s)
- Kadir Agladioglu
- 1 Pamukkale University, Medical School, Department of Radiology, Denizli, Turkey
| | - Gökhan Pekel
- 2 Pamukkale University, Medical School, Department of Ophtalmology, Denizli, Turkey
| | | | - Ramazan Yagci
- 2 Pamukkale University, Medical School, Department of Ophtalmology, Denizli, Turkey
| | - Yilmaz Kiroglu
- 1 Pamukkale University, Medical School, Department of Radiology, Denizli, Turkey
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