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Cheng C. Tissue, cellular, and molecular level determinants for eye lens stiffness and elasticity. FRONTIERS IN OPHTHALMOLOGY 2024; 4:1456474. [PMID: 39176256 PMCID: PMC11339033 DOI: 10.3389/fopht.2024.1456474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 07/26/2024] [Indexed: 08/24/2024]
Abstract
The eye lens is a transparent, ellipsoid tissue in the anterior chamber that is required for the fine focusing of light onto the retina to transmit a clear image. The focusing function of the lens is tied to tissue transparency, refractive index, and biomechanical properties. The stiffness and elasticity or resilience of the human lens allows for shape changes during accommodation to focus light from objects near and far. It has long been hypothesized that changes in lens biomechanical properties with age lead to the loss of accommodative ability and the need for reading glasses with age. However, the cellular and molecular mechanisms that influence lens biomechanical properties and/or change with age remain unclear. Studies of lens stiffness and resilience in mouse models with genetic defects or at advanced age inform us of the cytoskeletal, structural, and morphometric parameters that are important for biomechanical stability. In this review, we will explore whether: 1) tissue level changes, including the capsule, lens volume, and nucleus volume, 2) cellular level alterations, including cell packing, suture organization, and complex membrane interdigitations, and 3) molecular scale modifications, including the F-actin and intermediate filament networks, protein modifications, lipids in the cell membrane, and hydrostatic pressure, influence overall lens biomechanical properties.
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Affiliation(s)
- Catherine Cheng
- School of Optometry and Vision Science Program, Indiana University, Bloomington, IN, United States
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2
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Qiang B, Xu Q, Hu A, Fang J, Shen C, Zhang Y, Wang J. Feasibility of shear wave elastography for evaluating lens stiffness in patients with age-related cataracts: A quantitative analysis. Heliyon 2024; 10:e32255. [PMID: 38882265 PMCID: PMC11180308 DOI: 10.1016/j.heliyon.2024.e32255] [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: 09/20/2023] [Revised: 05/29/2024] [Accepted: 05/30/2024] [Indexed: 06/18/2024] Open
Abstract
Background Shear wave elastography (SWE) is a novel imaging technique that provides quantitative assessments of tissue stiffness. This non-invasive method offers real-time, quantitative measurements and has been widely applied to various tissues, providing valuable diagnostic insights. Purpose This study aimed to investigate the feasibility of using SWE to evaluate the stiffness of the lens in patients with age-related cataracts. Materials and methods A comparative analysis involving 92 patients diagnosed with age-related cataracts and 39 healthy controls was conducted. Lens stiffness was quantified using SWE measurements. The lens nucleus of all participants was graded based on the Lens Opacities Classification System II (LOCS II). Correlations between the stiffness of the lens and age were also analyzed. Results The study indicates that both the stiffness of the lens and the lens nucleus were significantly higher in patients with age-related cataracts compared to healthy controls (P < 0.001). In patients with age-related cataracts, although lens nucleus stiffness variations across different grades of cataract severity were not statistically significant, all grades displayed increased stiffness relative to healthy controls. Additionally, a significant positive correlation between lens stiffness and age was observed in all participants (P < 0.001). Conclusion SWE appears to be a promising imaging technique for quantitatively assessing the mechanical characteristics of the lens in patients with age-related cataracts.
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Affiliation(s)
- Banghong Qiang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Qiancheng Xu
- Department of Critical Care Medicine, The First Affiliated Hospital of Wannan Medical College (Yijishan Hospital of Wannan Medical College), Wuhu, 241000, Anhui, China
| | - Aili Hu
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Jiagui Fang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Chunyun Shen
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Yu Zhang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
| | - Junli Wang
- Department of Ultrasound Medicine, Wuhu Hospital, East China Normal University (The Second People's Hospital, Wuhu), Wuhu, 241000, Anhui, China
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Tahsini V, Gil IC, Kling S. Storage-induced mechanical changes of porcine lenses assessed with optical coherence elastography and inverse finite element modeling. Front Bioeng Biotechnol 2024; 12:1398659. [PMID: 38938986 PMCID: PMC11208870 DOI: 10.3389/fbioe.2024.1398659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Accepted: 05/27/2024] [Indexed: 06/29/2024] Open
Abstract
Introduction In an effort of gaining a better understanding of the lens mechanics, ex vivo lenses samples are often used. Yet, ex vivo tissue might undergo important postmortem changes depending on the unavoidable preservation method employed. The purpose of this study was to assess how various storage conditions and the removal of the lens capsule affect the mechanical properties of ex vivo porcine lens samples. Methods A total of 81 freshly enucleated porcine eyes were obtained and divided into six groups and preserved differently. In the first three groups, the lens within the intact eye was preserved for 24 h by: (i) freezing at -80°C (n = 12), (ii) freezing at -20°C (n = 12), and (iii) refrigeration at +8°C (n = 12). In the remaining groups, the lenses were immediately extracted and treated as follows: (iv) kept intact, no storage (n = 12), (v) decapsulated, no storage (n = 21), and (vi) immersed in Minimum Essential Medium (MEM) at +8°C (n = 12) for 24 h. Frozen lenses were thawed at room temperature. Each lens was compressed between two glass lamella and subjected, first to a period of relaxation during which the compression force was recorded and second to an oscillating micro-compression while the deformation was recorded with a total of 256 subsequent B-scans via optical coherence tomography. The corresponding axial strain was retrieved via phase-sensitive image processing and subsequently used as input for an inverse finite element analysis (iFEA) to retrieve the visco-hyperelastic material properties of the lenses. Results After freezing at temperatures of -80°C and -20°C, the cortical strains increased by 14% (p = 0.01) and 34% (p < 0.001), and the nuclear strains decreased by 17% (p = 0.014) and 36% (p < 0.001), compared to the lenses tested immediately after postmortem, respectively. According to iFEA, this resulted from an increased ratio of the nuclear: cortical E-modulus (4.06 and 7.06) in -80°C and -20°C frozen lenses compared to fresh lenses (3.3). Decapsulation had the largest effect on the material constant C10, showing an increase both in the nucleus and cortex. Preservation of the intact eye in the refrigerator induced the least mechanical alterations in the lens, compared to the intact fresh condition. Discussion Combining iFEA with optical coherence elastography allowed us to identify important changes in the lens mechanics induced after different preserving ex vivo methods.
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Affiliation(s)
- Vahoura Tahsini
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Iulen Cabeza Gil
- Aragón Institute of Engineering Research (i3A), University of Zaragoza, Zaragoza, Spain
| | - Sabine Kling
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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Kim GS, Moon HH, Lee HS, Jeong JS. Compound Acoustic Radiation Force Impulse Imaging of Bovine Eye by Using Phase-Inverted Ultrasound Transducer. SENSORS (BASEL, SWITZERLAND) 2024; 24:2700. [PMID: 38732804 PMCID: PMC11085659 DOI: 10.3390/s24092700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 04/19/2024] [Accepted: 04/22/2024] [Indexed: 05/13/2024]
Abstract
In general, it is difficult to visualize internal ocular structure and detect a lesion such as a cataract or glaucoma using the current ultrasound brightness-mode (B-mode) imaging. This is because the internal structure of the eye is rich in moisture, resulting in a lack of contrast between tissues in the B-mode image, and the penetration depth is low due to the attenuation of the ultrasound wave. In this study, the entire internal ocular structure of a bovine eye was visualized in an ex vivo environment using the compound acoustic radiation force impulse (CARFI) imaging scheme based on the phase-inverted ultrasound transducer (PIUT). In the proposed method, the aperture of the PIUT is divided into four sections, and the PIUT is driven by the out-of-phase input signal capable of generating split-focusing at the same time. Subsequently, the compound imaging technique was employed to increase signal-to-noise ratio (SNR) and to reduce displacement error. The experimental results demonstrated that the proposed technique could provide an acoustic radiation force impulse (ARFI) image of the bovine eye with a broader depth-of-field (DOF) and about 80% increased SNR compared to the conventional ARFI image obtained using the in-phase input signal. Therefore, the proposed technique can be one of the useful techniques capable of providing the image of the entire ocular structure to diagnose various eye diseases.
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Affiliation(s)
| | | | | | - Jong Seob Jeong
- Department of Biomedical Engineering, Dongguk University, Seoul 04620, Republic of Korea; (G.S.K.); (H.H.M.); (H.S.L.)
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Goody N, Israeliantz N, Massidda A, Richardson J, Blacklock B, Mitchell J, Liuti T. Ocular biometry in rabbits using computed tomography. Vet Ophthalmol 2024. [PMID: 38468158 DOI: 10.1111/vop.13209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 02/11/2024] [Accepted: 02/28/2024] [Indexed: 03/13/2024]
Abstract
OBJECTIVE To describe a repeatable method of measuring ocular structures and to establish ocular biometry reference ranges in adult domestic rabbits (Oryctolagus cuniculus) without medical history or imaging findings consistent with ophthalmic disease using a 64-slice multidetector computed tomography scanner. PROCEDURE In this retrospective and observational anatomic study, 100 eyes from 50 rabbits without medical history or imaging findings consistent with ophthalmic disease who received a head computed tomography scan were selected for measurement of globe length, width, and height using 3D multiplanar reconstruction. Lens width and length, the anteroposterior length of the anterior and vitreous chambers, and attenuation of the lens and vitreous chamber were collected. These parameters were compared against age, sex, weight, body condition, and ear conformation. RESULTS A reference guide was established, with globe width being the largest dimension (18.03 ± 0.81 mm), followed by height (17.18 ± 0.69 mm) and then length (16.64 ± 0.66 mm). Increased weight was associated with an increase in globe height (p = 2.43 × 10-5 ), length (p = 1.63 × 10-4 ), and width (p = 7.0 × 10-3 ). Increased age was associated with increased lens attenuation (p = 1.28 × 10-7 ) and increased transverse lens width (p = 1.64 × 10-3 ). Inter- and intra-observer agreement was excellent. CONCLUSIONS CT is a reliable modality for measurement of ocular biometry dimensions in rabbits. These reference values can be applied to aid in identifying diseases that affect the dimensions of the ocular structures in rabbits over 18 months of age.
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Affiliation(s)
- Nicholas Goody
- Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, The University of Edinburgh, Midlothian, UK
| | - Nicolas Israeliantz
- Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, The University of Edinburgh, Midlothian, UK
| | | | - Jenna Richardson
- Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, The University of Edinburgh, Midlothian, UK
| | - Benjamin Blacklock
- Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, The University of Edinburgh, Midlothian, UK
| | - Jordan Mitchell
- The Roslin Institute, The University of Edinburgh, Midlothian, UK
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hertfordshire, UK
| | - Tiziana Liuti
- Royal (Dick) School of Veterinary Studies, Hospital for Small Animals, The University of Edinburgh, Midlothian, UK
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de la Hoz A, Martinez-Enriquez E, Marcos S. Estimation of Crystalline Lens Material Properties From Patient Accommodation Data and Finite Element Models. Invest Ophthalmol Vis Sci 2023; 64:31. [PMID: 37639248 PMCID: PMC10461688 DOI: 10.1167/iovs.64.11.31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 08/03/2023] [Indexed: 08/29/2023] Open
Abstract
Purpose The mechanical properties of the crystalline lens are related to its optical function of accommodation, and their changes with age are one of the potential causes for presbyopia. We estimated the mechanical parameters of the crystalline lens using quantitative optical coherence tomography (OCT) imaging and wavefront sensing data from accommodating participants and computer modeling. Methods Full-lens shape data (from quantitative swept-source OCT and eigenlens representation) and optical power data (from Hartmann-Shack wavefront sensor) were obtained from 11 participants (22-30 years old) for relaxed accommodation at infinity and -4.5 D accommodative demand. Finite element models of lens, capsular bag, zonulae, and ciliary body were constructed using measured lens geometry and literature data, assuming a 60-mN radial force. An inverse modeling scheme was used to determine the shear moduli of the nucleus and cortex of the lens, such that the simulated deformed (maximally stretched) lens matched the participant's lens at -4.5 D. Results The shear moduli of the nucleus and cortex were 1.62 ± 1.32 and 8.18 ± 5.63 kPa, on average, respectively. The shear modulus of the nucleus was lower than that of the cortex for all participants evaluated. The average of the two moduli per participant was statistically significantly correlated with age (R2 = 0.76, P = 0.0049). Conclusions In vivo imaging and mechanical modeling of the crystalline lens allow estimations of the crystalline lens' mechanical properties. Differences between nuclear and cortical moduli and their dependency with age appear to be critical in accommodative function and likely in its impairment in presbyopia.
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Affiliation(s)
- Andres de la Hoz
- Instituto de Óptica “Daza de Valdés,” Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
| | - Eduardo Martinez-Enriquez
- Instituto de Óptica “Daza de Valdés,” Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
| | - Susana Marcos
- Center for Visual Science, The Institute of Optics, Flaum Eye Institute, University of Rochester, New York, United States
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Li R, Qian X, Gong C, Zhang J, Liu Y, Xu B, Humayun MS, Zhou Q. Simultaneous Assessment of the Whole Eye Biomechanics Using Ultrasonic Elastography. IEEE Trans Biomed Eng 2023; 70:1310-1317. [PMID: 36260593 PMCID: PMC10365545 DOI: 10.1109/tbme.2022.3215498] [Citation(s) in RCA: 28] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Current elastography techniques in the field of ophthalmology usually target one specific tissue, such as the cornea or the sclera. However, the eye is an inter-related organ, and some ocular diseases can alter the biomechanical properties of multiple anatomical structures. Hence, there is a need to develop an imaging tool that can non-invasively, quantitatively, and accurately characterize dynamic changes among these biomechanical properties. METHODS A high resolution ultrasound elastography system was developed to achieve this goal. The efficacy and accuracy of the system was first validated on tissue-mimicking phantoms while mechanical testing measurements served as the gold standard. Next, an in vivo elevated intraocular pressure (IOP) model was established in rabbits to further test our system. In particular, elastography measurements were obtained at 5 IOP levels, ranging from 10 mmHg to 30 mmHg in 5 mmHg increments. Spatial-temporal maps of the multiple ocular tissues (cornea, lens, iris, optic nerve head, and peripapillary sclera) were obtained. RESULTS The spatial-temporal maps were acquired simultaneously for the ocular tissues at the 5 different IOP levels. The statistical analysis of the elastic wave speed was presented for ocular tissues. Finally, the mapping for the elastic wave speed of each ocular component was acquired at each IOP level. CONCLUSION Our elastography system can concurrently assess the biomechanical properties of multiple ocular structures and detect changes in biomechanical properties associated with changes in IOP. SIGNIFICANCE This system provides a novel tool to measure and quantify the biomechanical properties of the whole eye.
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Chen Y, Ye S, Wang Q, Shen M, Lu F, Qu J, Zhu D. In situ assessment of lens elasticity with noncontact optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2022; 13:6671-6681. [PMID: 36589560 PMCID: PMC9774883 DOI: 10.1364/boe.475306] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 06/17/2023]
Abstract
Lens biomechanics has great potential for application in clinical diagnostics and treatment monitoring of presbyopia and cataracts. However, current approaches to lens elastography do not meet the desired safety or sensitivity for clinical application. In this regard, we propose a noncontact optical coherence elastography (OCE) method to facilitate quantitative in situ imaging of lens elasticity. Elastic waves induced by air-pulse stimulation on the limbus propagate to the lens and are then imaged using custom-built swept-source optical coherence tomography to obtain the elastic wave velocity and Young's modulus. The proposed OCE method was first validated by comparing the results of in situ and in vitro measurements of porcine lenses. The results demonstrate that the Young's modulus measured in situ was highly consistent with that measured in vitro and had an intraclass correlation coefficient of 0.988. We further investigated the elastic changes induced by cold storage and microwave heating. During 36-hour cold storage, the mean Young's modulus gradually increased (from 5.62 ± 1.24 kPa to 11.40 ± 2.68 kPa, P < 0.0001, n = 9) along with the formation of nuclear opacities. 15-second microwave heating caused a greater increase in the mean Young's modulus (from 6.86 ± 1.21 kPa to 25.96 ± 8.64 kPa, P < 0.0025, n = 6) without apparent cataract formation. Accordingly, this study reports the first air-pulse OCE measurements of in situ lenses, which quantified the loss of lens elasticity during simulated cataract development with good repeatability and sensitivity, thus enhancing the potential for adoption of lens biomechanics in the clinic.
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Affiliation(s)
- Yulei Chen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Shuling Ye
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Qingying Wang
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Meixiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Jia Qu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
| | - Dexi Zhu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China
- State Key Laboratory of Optometry, Ophthalmology, and Vision Science, Wenzhou, China
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Parmar A, Sharma G, Ramming A, Singh K. Deep Tissue Characterization with Optical Coherence Elastography: A Comparison of Different Methods. MATERIALS (BASEL, SWITZERLAND) 2022; 15:8558. [PMID: 36500053 PMCID: PMC9740038 DOI: 10.3390/ma15238558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/10/2022] [Accepted: 11/24/2022] [Indexed: 06/17/2023]
Abstract
The measurement of the biomechanical properties of the skin is of great interest since these properties play an important role in the development of several diseases such as skin cancer and systemic sclerosis. In this direction, several diagnostic tools have been developed to analyze the mechanical properties of the skin. Optical coherence elastography (OCE) is one of the emerging imaging techniques used for the characterization of the mechanical properties of the tissue quantitatively. In systemic sclerosis patients, the measurement of the mechanical properties of the deeper skin layers is desirable compared to the superficial layers. There are several variants of OCE that exist, but it is still not clear which method is more suitable for the measurement of the mechanical properties of the deeper tissue. In this work, we tested three common methods, the pulsed excitation method, the continuous wave excitation method, and the resonant frequency method, for the measurement of the mechanical properties of the deeper layers in the tissue. We found out that the pulsed wave excitation method provides the most reliable measurements in the shortest possible time compared to the other two methods.
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Affiliation(s)
- Asha Parmar
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91054 Erlangen, Germany
- Department of Physics, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Gargi Sharma
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Department of Medicine 1, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Andreas Ramming
- Department of Medicine 3, Universitätsklinikum Erlangen, Friedrich-Alexander-University Erlangen-Nürnberg, 91054 Erlangen, Germany
| | - Kanwarpal Singh
- Max Planck Institute for the Science of Light, 91058 Erlangen, Germany
- Max-Planck-Zentrum für Physik und Medizin, 91054 Erlangen, Germany
- Department of Physics, Friedrich-Alexander-University Erlangen-Nürnberg, 91058 Erlangen, Germany
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Zhang J, Fan F, Zhu L, Wang C, Chen X, Xinxiao G, Zhu J. Elasticity measurements of ocular anterior and posterior segments using optical coherence elastography. OPTICS EXPRESS 2022; 30:14311-14318. [PMID: 35473177 DOI: 10.1364/oe.456065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 04/01/2022] [Indexed: 06/14/2023]
Abstract
The changes of biomechanical properties, especially the elasticity of the ocular tissues, are closely related to some ophthalmic diseases. Currently, the ophthalmic optical coherence elastography (OCE) systems are dedicated either to the anterior segment or to the retina. The elasticity measurements of the whole eye remain challenging. Here we demonstrated an acoustic radiation force optical coherence elastography (ARF-OCE) method to quantify the elasticity of the cornea and the retina. The experiment results show that the Young's moduli of the cornea and the retina were 16.66 ± 6.51 kPa and 207.96 ± 4.75 kPa, respectively. Our method can measure the elasticity of the anterior segment and the posterior segment, and provides a powerful tool to enhance ophthalmology research.
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Cheng C, Wang K, Hoshino M, Uesugi K, Yagi N, Pierscionek B. EphA2 Affects Development of the Eye Lens Nucleus and the Gradient of Refractive Index. Invest Ophthalmol Vis Sci 2022; 63:2. [PMID: 34978559 PMCID: PMC8742528 DOI: 10.1167/iovs.63.1.2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Purpose Our studies in mouse eye lenses demonstrate that ephrin-A5 and EphA2 are needed for normal epithelial cells and lens transparency. We sought to determine whether EphA2 and ephrin-A5 are important for lens morphometrics, nucleus formation, and refractive index. Methods We performed tissue morphometric measurements, electron microscopy, Western blots, and interferometric measurements using an X-ray synchrotron beam source to measure the gradient of refractive index (GRIN) to compare mouse lenses with genetic disruption of EphA2 or ephrin-A5. Results Morphometric analysis revealed that although there is no change in the overall lens volume, there is a change in lens shape in both EphA2-/- lenses and ephrin-A5-/- lenses. Surprisingly, EphA2-/- lenses had small and soft lens nuclei different from hard lens nuclei of control lenses. SEM images revealed changes in cell morphology of EphA2-/- fiber cells close to the center of the lens. Inner EphA2-/- lens fibers had more pronounced tongue-and-groove interdigitations and formed globular membrane morphology only in the deepest layers of the lens nucleus. We did not observe nuclear defects in ephrin-A5-/- lenses. There was an overall decrease in magnitude of refractive index across EphA2-/- lenses, which is most pronounced in the nucleus. Conclusions This work reveals that Eph-ephrin signaling plays a role in fiber cell maturation, nuclear compaction, and lens shape. Loss of EphA2 disrupts the nuclear compaction resulting in a small lens nucleus. Our data suggest that Eph-ephrin signaling may be required for fiber cell membrane reorganization and compaction and for establishing a normal GRIN.
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Affiliation(s)
- Catherine Cheng
- School of Optometry, Indiana University, Bloomington, IN, United States
| | - Kehao Wang
- Beijing Advanced Innovation Centre for Biomedical Engineering, Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Engineering Medicine, Beihang University, Beijing, China
| | - Masato Hoshino
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 Japan
| | - Naoto Yagi
- Japan Synchrotron Radiation Research Institute (Spring-8), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 Japan
| | - Barbara Pierscionek
- Faculty of Health, Education, Medicine and Social Care, Medical Technology Research Centre, Anglia Ruskin University, Chelmsford Campus, United Kingdom
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Bontzos G, Douglas VP, Douglas KAA, Kapsala Z, Drakonaki EE, Detorakis ET. Ultrasound Elastography in Ocular and Periocular Tissues: A Review. Curr Med Imaging 2021; 17:1041-1053. [PMID: 33319691 DOI: 10.2174/1573405616666201214123117] [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] [Received: 06/13/2020] [Revised: 08/31/2020] [Accepted: 10/15/2020] [Indexed: 11/22/2022]
Abstract
Ultrasound elastography has become available in everyday practice, allowing direct measurement of tissue elasticity with important and expanding clinical applications. Several studies that have evaluated pathological and non-pathological tissues have demonstrated that ultrasound elastography can actually improve the diagnostic accuracy of the underlying disease process by detecting differences in their elasticity. Ocular and periocular tissues can also be characterized by their elastic properties. In this context, a comprehensive review of literature on ultrasound elastography as well as its current applications in Ophthalmology is presented.
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Affiliation(s)
- Georgios Bontzos
- Department of Ophthalmology, University Hospital of Heraklion, Crete, Greece
| | | | | | - Zoi Kapsala
- Department of Ophthalmology, University Hospital of Heraklion, Crete, Greece
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Khadka NK, Timsina R, Rowe E, O'Dell M, Mainali L. Mechanical properties of the high cholesterol-containing membrane: An AFM study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183625. [PMID: 33891910 DOI: 10.1016/j.bbamem.2021.183625] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 04/02/2021] [Accepted: 04/12/2021] [Indexed: 12/11/2022]
Abstract
Cholesterol (Chol) content in most cellular membranes does not exceed 50 mol%, only in the eye lens's fiber cell plasma membrane, its content surpasses 50 mol%. At this high concentration, Chol induces the formation of pure cholesterol bilayer domains (CBDs), which coexist with the surrounding phospholipid-cholesterol domain (PCD). Here, we applied atomic force microscopy to study the mechanical properties of Chol/phosphatidylcholine membranes where the Chol content was increased from 0 to 75 mol%, relevant to eye lens membranes. The surface roughness of the membrane decreases with an increase of Chol content until it reaches 60 mol%, and roughness increases with a further increment in Chol content. We propose that the increased roughness at higher Chol content results from the formation of CBDs. Force spectroscopy on the membrane with Chol content of 50 mol% or lesser exhibited single breakthrough events, whereas two distinct puncture events were observed for membranes with the Chol content greater than 50 mol%. We propose that the first puncture force corresponds to the membranes containing coexisting PCD and CBDs. In contrast, the second puncture force corresponds to the "CBD water pocket" formed due to coexisting CBDs and PCD. Membrane area compressibility modulus (KA) increases with an increase in Chol content until it reaches 60 mol%, and with further increment in Chol content, CBDs are formed, and KA starts to decrease. Our results report the increase in membrane roughness and decrease KA at very high Chol content (>60 mol%) relevant to the eye lens membrane.
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Affiliation(s)
- Nawal K Khadka
- Department of Physics, Boise State University, Boise, ID, USA
| | - Raju Timsina
- Department of Physics, Boise State University, Boise, ID, USA
| | - Erica Rowe
- Department of Biology, Boise State University, Boise, ID, USA
| | - Matthew O'Dell
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, USA
| | - Laxman Mainali
- Department of Physics, Boise State University, Boise, ID, USA; Biomolecular Sciences Graduate Program, Boise State University, Boise, ID, USA.
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14
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Zhou HY, Yan H, Yan WJ, Wang XC. Ultrasound elastography for evaluating stiffness of the human lens nucleus with aging: a feasibility study. Int J Ophthalmol 2021; 14:240-244. [PMID: 33614452 DOI: 10.18240/ijo.2021.02.09] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 04/21/2020] [Indexed: 11/23/2022] Open
Abstract
AIM To investigate the significance of ultrasound elastography for evaluating stiffness of the human lens nucleus in volunteers with different ages. METHODS A total of 90 volunteers (lens transparency, uncorrected visual acuity ≥0.5, intraocular pressure: 14-19 mm Hg) were divided into 3 groups according to age: Group A (30 people, median age: 82±3.5y, mean axial lengths 23.7±0.5 mm); Group B (30 people, median age: 46±2.1y, mean axial lengths 23.9±0.4 mm); and Group C (30 people, median age: 22±3.5y, mean axial lengths 24.0±0.4 mm). Lens nuclear stiffness was measured by Free-hand qualitative elastography by independent operators. Strain gray scale and color-coded elastography maps were recorded. In each case, three consecutive detections were performed and strain ratio was used for statistical analysis. RESULTS Elastography analysis showed excellent diagnostic performance for lens sclerosis. Lens strain ratio was lowest (0.03±0.01)% in Group A and highest (2.03±0.43)% in Group C. Lens strain ratio was moderate (0.64±0.10)% in Group B. There were significant differences between these three groups (P<0.05). The lens nucleus strain rate changes with age. With aging, the lens nucleus strain rate and resilience decrease, demonstrating harder texture. CONCLUSION The relationship between human lens stiffness and age is demonstrated by ultrasound elastography. Older age is associated with lower strain ratio and less resilience of the lens.
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Affiliation(s)
- Hai-Yan Zhou
- Department of Ophthalmology, Shaanxi Provincial People's Hospital, Third Affiliated Hospital of the School of Medicine, Xi'an Jiaotong University, Xi'an 710068, Shaanxi Province, China
| | - Hong Yan
- Department of Ophthalmology, Xi'an No.4 Hospital, Shaanxi Eye Hospital, Affiliated Guangren Hospital School of Medicine, Xi'an Jiaotong University, Xi'an 710004, Shaanxi Province, China
| | - Wei-Jia Yan
- Medical School, the University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Xin-Chuan Wang
- Shaanxi Traditional Chinese Medicine Hospital, Xi'an 710003, Shaanxi Province, China
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15
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Li Y, Moon S, Chen JJ, Zhu Z, Chen Z. Ultrahigh-sensitive optical coherence elastography. LIGHT, SCIENCE & APPLICATIONS 2020; 9:58. [PMID: 32337022 PMCID: PMC7154028 DOI: 10.1038/s41377-020-0297-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/16/2020] [Accepted: 03/19/2020] [Indexed: 05/07/2023]
Abstract
The phase stability of an optical coherence elastography (OCE) system is the key determining factor for achieving a precise elasticity measurement, and it can be affected by the signal-to-noise ratio (SNR), timing jitters in the signal acquisition process, and fluctuations in the optical path difference (OPD) between the sample and reference arms. In this study, we developed an OCE system based on swept-source optical coherence tomography (SS-OCT) with a common-path configuration (SS-OCECP). Our system has a phase stability of 4.2 mrad without external stabilization or extensive post-processing, such as averaging. This phase stability allows us to detect a displacement as small as ~300 pm. A common-path interferometer was incorporated by integrating a 3-mm wedged window into the SS-OCT system to provide intrinsic compensation for polarization and dispersion mismatch, as well as to minimize phase fluctuations caused by the OPD variation. The wedged window generates two reference signals that produce two OCT images, allowing for averaging to improve the SNR. Furthermore, the electrical components are optimized to minimize the timing jitters and prevent edge collisions by adjusting the delays between the trigger, k-clock, and signal, utilizing a high-speed waveform digitizer, and incorporating a high-bandwidth balanced photodetector. We validated the SS-OCECP performance in a tissue-mimicking phantom and an in vivo rabbit model, and the results demonstrated a significantly improved phase stability compared to that of the conventional SS-OCE. To the best of our knowledge, we demonstrated the first SS-OCECP system, which possesses high-phase stability and can be utilized to significantly improve the sensitivity of elastography.
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Affiliation(s)
- Yan Li
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92612 USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617 USA
| | - Sucbei Moon
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92612 USA
- Department of Physics, Kookmin University, Seoul, 02707 South Korea
| | - Jason J. Chen
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92612 USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617 USA
| | - Zhikai Zhu
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92612 USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617 USA
| | - Zhongping Chen
- Beckman Laser Institute, University of California, Irvine, Irvine, CA 92612 USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, CA 92617 USA
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16
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In vivo ultraosound elastographic evaluation of the age-related change of human lens nuclear stiffness. BMC Ophthalmol 2020; 20:135. [PMID: 32252697 PMCID: PMC7137519 DOI: 10.1186/s12886-020-01404-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Accepted: 03/25/2020] [Indexed: 11/26/2022] Open
Abstract
Background To evaluate the age-related changes in the stiffness of the human lens nucleus in vivo. Methods A total of 78 volunteers with best-corrected visual acuity of 20/20with a mean ± standard deviation intraocular pressure (IOP) of 16 ± 2.5 mmHg were divided into 3 groups of 26. The mean ages of Groups A, B and C were 81 ± 5.5, 44 ± 3.2 and 21 ± 2.5 years, with mean axial lengths of 23.8 ± 0.5 mm, 23.8 ± 0.4 mm and 23.9 ± 0.3 mm, respectively. Using an elastographer, the ultrasound echolucency and elastic strain rate of the lens nucleus of one eye, selected randomly, of each subject were measured three times. The strain rate of the lens cortex could not be assessed. The qualitative differences in the strain rates across the groups were assessed, and differences in the strain rate ratios of the lens nuclei across groups were analysed by one-way ANOVA. Results The strain rates of the lens nuclei of Group A were much lower than those in Groups B and C, as assessed qualitatively; the elastograph images of the lens nuclei of the older group showed a blue colour.The strain rate ratios of the lens nuclei of Groups A, B and C were 0.02 ± 0.08, 0.69 ± 0.12 and 1.95 ± 0.85, respectively. The differences in the lens nucleus strain rate ratios across the groups were statistically significant, with p-values < 0.05. Conclusions Ultrasound elastography demonstrated in vivo that an older age is associated with a statistically significantly lower lens nucleus strain rate ratio and therefore a markedly higher lens nuclear stiffness.
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Ambekar YS, Singh M, Zhang J, Nair A, Aglyamov SR, Scarcelli G, Larin KV. Multimodal quantitative optical elastography of the crystalline lens with optical coherence elastography and Brillouin microscopy. BIOMEDICAL OPTICS EXPRESS 2020; 11:2041-2051. [PMID: 32341865 PMCID: PMC7173892 DOI: 10.1364/boe.387361] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/27/2020] [Accepted: 03/05/2020] [Indexed: 05/03/2023]
Abstract
Assessing the biomechanical properties of the crystalline lens can provide crucial information for diagnosing disease and guiding precision therapeutic interventions. Existing noninvasive methods have been limited to global measurements. Here, we demonstrate the quantitative assessment of the elasticity of crystalline lens with a multimodal optical elastography technique, which combines dynamic wave-based optical coherence elastography (OCE) and Brillouin microscopy to overcome the drawbacks of individual modalities. OCE can provide direct measurements of tissue elasticity rapidly and quantitatively, but it is a challenge to image transparent samples such as the lens because this technique relies on backscattered light. On the other hand, Brillouin microscopy can map the longitudinal modulus with micro-scale resolution in transparent samples. However, the relationship between Brillouin-deduced modulus and Young's modulus is not straightforward and sample dependent. By combining these two techniques, we can calibrate Brillouin measurements with OCE, based on the same sample, allowing us to completely map the Young's modulus of the crystalline lens. The combined system was first validated with tissue-mimicking gelatin phantoms of varying elasticities (N = 9). The OCE data was used to calibrate the Brillouin shift measurements and subsequently map the Young's modulus of the phantoms. After validation, OCE and Brillouin measurements were performed on ex-vivo porcine lenses (N = 6), and the Young's modulus of the lenses was spatially mapped. The results show a strong correlation between Young's moduli measured by OCE and longitudinal moduli measured by Brillouin microscopy. The correlation coefficient R was 0.98 for the phantoms and 0.94 for the lenses, respectively. The mean Young's modulus of the anterior and posterior lens was 1.98 ± 0.74 kPa and 2.93 ± 1.13 kPa, respectively, and the Young's modulus of the lens nucleus was 11.90 ± 2.94 kPa. The results presented in this manuscript open a new way for truly quantitative biomechanical mapping of optically transparent (or low scattering) tissues in 3D.
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Affiliation(s)
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX 77030, USA
| | - Jitao Zhang
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Achuth Nair
- Department of Biomedical Engineering, University of Houston, Houston, TX 77030, USA
| | - Salavat R. Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX 77030, USA
| | - Giuliano Scarcelli
- Fischell Department of Bioengineering, University of Maryland, College Park, MD 20742, USA
| | - Kirill V. Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX 77030, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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18
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Zhou HY, Yan H, Yan WJ, Wang XC, Li QY. Noninvasive stiffness assessment of the human lens nucleus in patients with anisometropia using an ultrasound elastography system. Int J Ophthalmol 2020; 13:399-405. [PMID: 32309175 DOI: 10.18240/ijo.2020.03.05] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Accepted: 01/20/2020] [Indexed: 12/18/2022] Open
Abstract
AIM To investigate the significance of ultrasound elastography for evaluating stiffness of the human lens nucleus in patients with anisometropia. METHODS A total of 14 patients (28 eyes) with anisometropia were enrolled. The difference in refractive status between two eyes ≥-4.0 diopters (D) and the difference in axial length (AL) of the eyes was ≥3 mm. There were 5 males and 9 females with an average age of 62±3.3y. The test data of the long AL eye of each patient was included in group A (14 eyes), and test data of the eye with relative short AL was included in group B. Lens nuclear stiffness was measured with free-hand qualitative elastography by independent operators. Strain gray scale and color-coded elastography maps were recorded. In each case, three consecutive measurements were performed and strain ratio was used for statistical analysis. Photograph and sectional view of the lens were analyzed and archived by anterior segment image. RESULTS In the long AL group, the strain rate in the nucleus of the lens was 0.16%±0.08%; in the short AL group, the strain rate in the nucleus of the lens was 0.54%±0.16%. Independent sample t-test analyses showed that the long AL group lens had a significantly smaller nuclear strain rate than the relatively short AL group, P<0.05. CONCLUSION The relationship between human lens stiffness and different AL is demonstrated by ultrasound elastography. The long AL is associated with lower strain ratio and less resilience of the lens.
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Affiliation(s)
- Hai-Yan Zhou
- Department of Ophthalmology, Shaanxi Provincial People's Hospital, Third Affiliated Hospital of the School of Medicine, Xi'an Jiaotong University, Xi'an 710038, Shaanxi Province, China
| | - Hong Yan
- Xi'an Fourth Hospital, Shaanxi Eye Hospital, Affiliated Xi'an Fourth Hospital, Northwestern Polytechnical University, Xi'an 710004, Shaanxi Province, China
| | - Wei-Jia Yan
- Medical School, the University of Sheffield, Western Bank, Sheffield, S10 2TN, UK
| | - Xin-Chuan Wang
- Basic Medical School, Air Force Medical University, Xi'an 710068, Shaanxi Province, China
| | - Qiao-Ying Li
- Department of UItrasonic Diagnosis, Tangdu Hospital, Air Force Medical University, Xi'an 710038, Shaanxi Province, China
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Cheng C, Parreno J, Nowak RB, Biswas SK, Wang K, Hoshino M, Uesugi K, Yagi N, Moncaster JA, Lo WK, Pierscionek B, Fowler VM. Age-related changes in eye lens biomechanics, morphology, refractive index and transparency. Aging (Albany NY) 2019; 11:12497-12531. [PMID: 31844034 PMCID: PMC6949082 DOI: 10.18632/aging.102584] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/26/2019] [Indexed: 04/09/2023]
Abstract
Life-long eye lens function requires an appropriate gradient refractive index, biomechanical integrity and transparency. We conducted an extensive study of wild-type mouse lenses 1-30 months of age to define common age-related changes. Biomechanical testing and morphometrics revealed an increase in lens volume and stiffness with age. Lens capsule thickness and peripheral fiber cell widths increased between 2 to 4 months of age but not further, and thus, cannot account for significant age-dependent increases in lens stiffness after 4 months. In lenses from mice older than 12 months, we routinely observed cataracts due to changes in cell structure, with anterior cataracts due to incomplete suture closure and a cortical ring cataract corresponding to a zone of compaction in cortical lens fiber cells. Refractive index measurements showed a rapid growth in peak refractive index between 1 to 6 months of age, and the area of highest refractive index is correlated with increases in lens nucleus size with age. These data provide a comprehensive overview of age-related changes in murine lenses, including lens size, stiffness, nuclear fraction, refractive index, transparency, capsule thickness and cell structure. Our results suggest similarities between murine and primate lenses and provide a baseline for future lens aging studies.
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Affiliation(s)
- Catherine Cheng
- School of Optometry, Indiana University, Bloomington, IN 47405, USA
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Justin Parreno
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
| | - Roberta B. Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Sondip K. Biswas
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA 30303, USA
| | - Kehao Wang
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Masato Hoshino
- Japan Synchrotron Radiation Research Institute (Spring-8), Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Kentaro Uesugi
- Japan Synchrotron Radiation Research Institute (Spring-8), Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Naoto Yagi
- Japan Synchrotron Radiation Research Institute (Spring-8), Sayo-cho, Sayo-gun, Hyogo, Japan
| | - Juliet A. Moncaster
- Department of Radiology, Boston University School of Medicine, Boston, MA 02118, USA
| | - Woo-Kuen Lo
- Department of Neurobiology, Morehouse School of Medicine, Atlanta, GA 30303, USA
| | - Barbara Pierscionek
- School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Velia M. Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA
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20
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Li Y, Zhu J, Chen JJ, Yu J, Jin Z, Miao Y, Browne AW, Zhou Q, Chen Z. Simultaneously imaging and quantifying in vivo mechanical properties of crystalline lens and cornea using optical coherence elastography with acoustic radiation force excitation. APL PHOTONICS 2019; 4:106104. [PMID: 32309636 PMCID: PMC7164808 DOI: 10.1063/1.5118258] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The crystalline lens and cornea comprise the eye's optical system for focusing light in human vision. The changes in biomechanical properties of the lens and cornea are closely associated with common diseases, including presbyopia and cataract. Currently, most in vivo elasticity studies of the anterior eye focus on the measurement of the cornea, while lens measurement remains challenging. To better understand the anterior segment of the eye, we developed an optical coherence elastography system utilizing acoustic radiation force excitation to simultaneously assess the elasticities of the crystalline lens and the cornea in vivo. A swept light source was integrated into the system to provide an enhanced imaging range that covers both the lens and the cornea. Additionally, the oblique imaging approach combined with orthogonal excitation also improved the image quality. The system was tested through first ex vivo and then in vivo experiments using a rabbit model. The elasticities of corneal and lens tissue in an excised normal whole-globe and a cold cataract model were measured to reveal that cataractous lenses have a higher Young's modulus. Simultaneous in vivo elasticity measurements of the lens and cornea were performed in a rabbit model to demonstrate the correlations between elasticity and intraocular pressure and between elasticity and age. To the best of our knowledge, we demonstrated the first in vivo elasticity of imaging of both the lens and cornea using acoustic radiation force-optical coherence elastography, thereby providing a potential powerful clinical tool to advance ophthalmic research in disorders affecting the lens and the cornea.
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Affiliation(s)
- Yan Li
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
| | - Jiang Zhu
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
| | - Jason J. Chen
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
| | - Junxiao Yu
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
| | - Zi Jin
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
| | - Yusi Miao
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
| | - Andrew W. Browne
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
- Department of Ophthalmology, School of Medicine, University of California, Irvine, Irvine, California 92617, USA
- Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California 92697, USA
| | - Qifa Zhou
- Department of Ophthalmology and Biomedical Engineering, University of Southern California, Los Angeles, California 90089, USA
- Roski Eye Institute, University of Southern California, Los Angeles, California 90007, USA
| | - Zhongping Chen
- Beckman Laser Institute, University of California, Irvine, Irvine, California 92612, USA
- Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, USA
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21
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Wang Q, Zhu Y, Shao M, Lin H, Chen S, Chen X, Alizad A, Fatemi M, Zhang X. In vivo assessment of the mechanical properties of crystalline lenses in a rabbit model using ultrasound elastography: Effects of ultrasound frequency and age. Exp Eye Res 2019; 184:258-265. [DOI: 10.1016/j.exer.2019.05.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 04/07/2019] [Accepted: 05/07/2019] [Indexed: 10/26/2022]
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22
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Zhang H, Wu C, Singh M, Nair A, Aglyamov SR, Larin KV. Optical coherence elastography of cold cataract in porcine lens. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-7. [PMID: 30864348 PMCID: PMC6444576 DOI: 10.1117/1.jbo.24.3.036004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Accepted: 02/19/2019] [Indexed: 05/08/2023]
Abstract
Cataract is one of the most prevalent causes of blindness around the world. Understanding the mechanisms of cataract development and progression is important for clinical diagnosis and treatment. Cold cataract has proven to be a robust model for cataract formation that can be easily controlled in the laboratory. There is evidence that the biomechanical properties of the lens can be significantly changed by cataract. Therefore, early detection of cataract, as well as evaluation of therapies, could be guided by characterization of lenticular biomechanical properties. In this work, we utilized optical coherence elastography (OCE) to monitor the changes in biomechanical properties of ex vivo porcine lenses during formation of cold cataract. Elastic waves were induced in the porcine lenses by a focused micro air-pulse while the lenses were cooled, and the elastic wave velocity was translated to Young's modulus of the lens. The results show an increase in the stiffness of the lens due to formation of the cold cataract (from 11.3 ± 3.4 to 21.8 ± 7.8 kPa). These results show a relation between lens opacity and stiffness and demonstrate that OCE can assess lenticular biomechanical properties and may be useful for detecting and potentially characterizing cataracts.
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Affiliation(s)
- Hongqiu Zhang
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Chen Wu
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Manmohan Singh
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Achuth Nair
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Salavat R. Aglyamov
- University of Houston, Department of Mechanical Engineering, Houston, Texas, United States
- University of Texas at Austin, Department of Biomedical Engineering, Austin, Texas, United States
| | - Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
- Address all correspondence to Kirill V. Larin, E-mail:
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23
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Wu C, Aglyamov SR, Han Z, Singh M, Liu CH, Larin KV. Assessing the biomechanical properties of the porcine crystalline lens as a function of intraocular pressure with optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2018; 9:6455-6466. [PMID: 31065442 PMCID: PMC6491010 DOI: 10.1364/boe.9.006455] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 11/11/2018] [Accepted: 11/14/2018] [Indexed: 05/04/2023]
Abstract
In this study, we investigated the relationship between the biomechanical properties of the crystalline lens and intraocular pressure (IOP) using a confocal acoustic radiation force (ARF) and phase-sensitive optical coherence elastography (OCE) system. ARF induced a small displacement at the apex of porcine lenses in situ at various artificially controlled IOPs. Maximum displacement, relaxation rate, and Young's modulus were utilized to assess the stiffness of the crystalline lens. The results showed that the stiffness of the crystalline increased as IOP increased, but the lens stiffening was not as significant as the stiffening of other ocular tissues such as the cornea and the sclera. A mechanical hysteresis in the lens was also observed while cycling IOP, indicating that the viscoelastic response of the lens is crucial to fully understanding its biomechanical properties.
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Affiliation(s)
- Chen Wu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Salavat R Aglyamov
- Department of Mechanical Engineering, University of Houston, Houston, TX 77204, USA
- Department of Biomedical Engineering, University of Texas, Austin, TX 78712, USA
| | - Zhaolong Han
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
- School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Manmohan Singh
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Chih-Hao Liu
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
| | - Kirill V Larin
- Department of Biomedical Engineering, University of Houston, Houston, TX 77204, USA
- Interdisciplinary Laboratory of Biophotonics, Tomsk State University, Tomsk, Russia
- Molecular Physiology and Biophysics, Baylor College of Medicine, TX 77584, USA
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