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Niemczyk M, Iskander DR. Measuring intraocular pressure with OCT: the first approach. BIOMEDICAL OPTICS EXPRESS 2023; 14:4531-4541. [PMID: 37791274 PMCID: PMC10545197 DOI: 10.1364/boe.500546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 07/18/2023] [Indexed: 10/05/2023]
Abstract
The variability of corneal OCT speckle statistics is indirectly related to changes in corneal microstructure, which may be induced by intraocular pressure (IOP). A new approach is considered, which attempts to estimate IOP based on corneal speckle statistics in OCT images. An area (A) under trajectories of contrast ratio with respect to stromal depth was calculated. The proposed method was evaluated on OCT images from the ex-vivo study on porcine eyeballs and in-vivo study on human corneas. A statistically significant multivariate linear regression model was obtained from the ex-vivo study: IOP = 0.70 · A - 6.11, in which IOP was precisely controlled in the anterior chamber. The ex-vivo study showed good correlation between A and IOP (R = 0.628, at the least) whereas the in-vivo study showed poor correlation between A and clinical air-puff tonometry based estimates of IOP (R = 0.351, at the most), indicating substantial differences between the two studies. The results of the ex-vivo study show the potential for OCT speckle statistics to be utilized for measuring IOP using static corneal imaging that does not require corneal deformation. Nevertheless, further work is needed to validate this approach in living human corneas.
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Affiliation(s)
- Marcela Niemczyk
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
| | - D. Robert Iskander
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wybrzeze Wyspianskiego 27, 50-370 Wroclaw, Poland
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Raoux C, Chessel A, Mahou P, Latour G, Schanne-Klein MC. Unveiling the lamellar structure of the human cornea over its full thickness using polarization-resolved SHG microscopy. LIGHT, SCIENCE & APPLICATIONS 2023; 12:190. [PMID: 37528091 PMCID: PMC10394036 DOI: 10.1038/s41377-023-01224-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/22/2023] [Accepted: 07/05/2023] [Indexed: 08/03/2023]
Abstract
A key property of the human cornea is to maintain its curvature and consequently its refraction capability despite daily changes in intraocular pressure. This is closely related to the multiscale structure of the corneal stroma, which consists of 1-3 µm-thick stacked lamellae made of thin collagen fibrils. Nevertheless, the distribution, size, and orientation of these lamellae along the depth of the cornea are poorly characterized up to now. In this study, we use second harmonic generation (SHG) microscopy to visualize the collagen distribution over the full depth of 10 intact and unstained human corneas (500-600 µm thick). We take advantage of the small coherence length in epi-detection to axially resolve the lamellae while maintaining the corneal physiological curvature. Moreover, as raw epi-detected SHG images are spatially homogenous because of the sub-wavelength size of stromal collagen fibrils, we use a polarimetric approach to measure the collagen orientation in every voxel. After a careful validation of this approach, we show that the collagen lamellae (i) are mostly oriented along the inferior-superior axis in the anterior stroma and along the nasal-temporal axis in the posterior stroma, with a gradual shift in between and (ii) exhibit more disorder in the anterior stroma. These results represent the first quantitative characterization of the lamellar structure of the human cornea continuously along its entire thickness with micrometric resolution. It also shows the unique potential of P-SHG microscopy for imaging of collagen distribution in thick dense tissues.
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Affiliation(s)
- Clothilde Raoux
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Anatole Chessel
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Pierre Mahou
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128, Palaiseau, France
| | - Gaël Latour
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128, Palaiseau, France
- Université Paris-Saclay, 91190, Gif-sur-Yvette, France
| | - Marie-Claire Schanne-Klein
- Laboratory for Optics and Biosciences, Ecole Polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128, Palaiseau, France.
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Bazin D, Daudon M, Frochot V, Haymann JP, Letavernier E. Foreword to microcrystalline pathologies: combining clinical activity and fundamental research at the nanoscale. CR CHIM 2022. [DOI: 10.5802/crchim.200] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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4
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Giraudet C, Diaz J, Le Tallec P, Allain JM. Multiscale mechanical model based on patient-specific geometry: Application to early keratoconus development. J Mech Behav Biomed Mater 2022; 129:105121. [DOI: 10.1016/j.jmbbm.2022.105121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 01/19/2022] [Accepted: 02/03/2022] [Indexed: 11/30/2022]
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Schmeltz M, Robinet L, Heu-Thao S, Sintès JM, Teulon C, Ducourthial G, Mahou P, Schanne-Klein MC, Latour G. Noninvasive quantitative assessment of collagen degradation in parchments by polarization-resolved SHG microscopy. SCIENCE ADVANCES 2021; 7:7/29/eabg1090. [PMID: 34272247 PMCID: PMC8284887 DOI: 10.1126/sciadv.abg1090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 06/02/2021] [Indexed: 06/13/2023]
Abstract
Nondestructive and noninvasive investigation techniques are highly sought-after to establish the degradation state of historical parchments, which is up to now assessed by thermal techniques that are invasive and destructive. We show that advanced nonlinear optical (NLO) microscopy enables quantitative in situ mapping of parchment degradation at the micrometer scale. We introduce two parameters that are sensitive to different degradation stages: the ratio of two-photon excited fluorescence to second harmonic generation (SHG) signals probes severe degradation, while the anisotropy parameter extracted from polarization-resolved SHG measurements is sensitive to early degradation. This approach is first validated by comparing NLO quantitative parameters to thermal measurements on artificially altered contemporary parchments. We then analyze invaluable parchments from the Middle Ages and show that we can map their conservation state and assess the impact of a restoration process. NLO quantitative microscopy should therefore help to identify parchments most at risk and optimize restoration methods.
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Affiliation(s)
- Margaux Schmeltz
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Laurianne Robinet
- Centre de Recherche sur la Conservation (CRC), Muséum national d'Histoire naturelle, Ministère de la Culture, CNRS, Paris, France
| | - Sylvie Heu-Thao
- Centre de Recherche sur la Conservation (CRC), Muséum national d'Histoire naturelle, Ministère de la Culture, CNRS, Paris, France
| | - Jean-Marc Sintès
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Claire Teulon
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Guillaume Ducourthial
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Pierre Mahou
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Marie-Claire Schanne-Klein
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France
| | - Gaël Latour
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, Palaiseau, France.
- Université Paris-Saclay, Saint-Aubin, France
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Raoux C, Schmeltz M, Bied M, Alnawaiseh M, Hansen U, Latour G, Schanne-Klein MC. Quantitative structural imaging of keratoconic corneas using polarization-resolved SHG microscopy. BIOMEDICAL OPTICS EXPRESS 2021; 12:4163-4178. [PMID: 34457406 PMCID: PMC8367248 DOI: 10.1364/boe.426145] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/29/2021] [Accepted: 05/22/2021] [Indexed: 05/20/2023]
Abstract
The human cornea is mainly composed of collagen fibrils aligned together within stacked lamellae. This lamellar structure can be affected in pathologies such as keratoconus, which is characterized by progressive corneal thinning and local steepening. In this study, we use polarization-resolved second harmonic generation (P-SHG) microscopy to characterize 8 control and 6 keratoconic human corneas. Automated processing of P-SHG images of transverse sections provides the collagen orientation in every pixel with sub-micrometer resolution. Series of P-SHG images recorded in the most anterior region of the stroma evidence sutural lamellae inclined at 22° ± 5° to the corneal surface, but show no significant difference between control and keratoconic corneas. In contrast, series of P-SHG images acquired along the full thickness of the stroma show a loss of order in the lamellar structure of keratoconic corneas, in agreement with their defective mechanical properties. This structural difference is analyzed quantitatively by computing the entropy and the orientation index of the collagen orientation distribution and significant differences are obtained along the full thickness of the stroma. This study shows that P-SHG is an effective tool for automatic quantitative analysis of structural defects of human corneas and should be applied to other collagen-rich tissues.
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Affiliation(s)
- Clothilde Raoux
- Laboratory for Optics and Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
- These authors contributed equally
| | - Margaux Schmeltz
- Laboratory for Optics and Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
- These authors contributed equally
| | - Marion Bied
- Laboratory for Optics and Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - Maged Alnawaiseh
- Department of Ophthalmology, Hospital Fulda, University of Marburg, Campus Fulda, 36043 Fulda, Germany
| | - Uwe Hansen
- Institute for Musculoskeletal Medicine, University Hospital Münster, 48149 Münster, Germany
| | - Gaël Latour
- Laboratory for Optics and Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
- Université Paris-Saclay, 91190 Saint-Aubin, France
| | - Marie-Claire Schanne-Klein
- Laboratory for Optics and Biosciences, Ecole polytechnique, CNRS, INSERM, Institut Polytechnique de Paris, 91128 Palaiseau, France
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Danielewska ME, Antonczyk A, Andrade De Jesus D, Rogala MM, Blonska A, Cwirko M, Kielbowicz Z, Iskander DR. Corneal Optical Coherence Tomography Speckle in Crosslinked and Untreated Rabbit Eyes in Response to Elevated Intraocular Pressure. Transl Vis Sci Technol 2021; 10:2. [PMID: 34003977 PMCID: PMC8088219 DOI: 10.1167/tvst.10.5.2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Purpose To ascertain the influence of intraocular pressure (IOP) on corneal optical coherence tomography (OCT) speckle in untreated and ultraviolet A–riboflavin induced corneal collagen crosslinked rabbit eyes. Methods Left corneas of eight rabbits were de-epithelialized and crosslinked by applying riboflavin and 30-minute ultraviolet A light exposure. After enucleation (6 months after treatment), each eyeball (treated and untreated) was mounted in a measurement setup, in which IOP was increased from 15 to 45 mm Hg in steps of 5 mm Hg. At each IOP value, single B-scans of the central cornea were acquired three times with the spectral-domain OCT Copernicus-HR. Then, three regions of interest, including the anterior, posterior, and entire corneal stroma, were automatically extracted. Five different probability distributions were used as a model for the corneal speckle and the one with the best goodness of fit was chosen for further analysis. Results The generalized gamma distribution achieved the best goodness of fit and its scale (a) and shape (v) parameters statistically significantly changed with increasing IOP in the three regions of analysis (two-way repeated measures analysis of variance, all P < 0.05). The statistically significant difference between untreated and crosslinked eyes was observed for the shape parameters of the posterior and entire corneal stroma. Conclusions Corneal OCT speckle is influenced by IOP and shows to be significantly different in untreated and crosslinked eyes. Corneal OCT speckle analysis has the potential to be indirectly used for assessing changes in corneal stroma in ex vivo and in vivo studies. Translational Relevance Investigation of corneal OCT speckle statistics can offer additional diagnostic biomarkers related to changes in the corneal stroma after ocular surgeries.
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Affiliation(s)
- Monika E Danielewska
- Wrocław University of Science and Technology, Department of Biomedical Engineering, Wrocław, Poland
| | - Agnieszka Antonczyk
- Wrocław University of Environmental and Life Sciences, Department of Surgery, Faculty of Veterinary Medicine, Wrocław, Poland
| | - Danilo Andrade De Jesus
- Erasmus University Medical Center, Department of Radiology and Nuclear Medicine, Biomedical Imaging Group Rotterdam, Rotterdam, The Netherlands
| | - Maja M Rogala
- Wrocław University of Science and Technology, Department of Mechanics, Materials and Biomedical Engineering, Wrocław, Poland
| | - Anna Blonska
- Ophthalmology Clinical Centre SPEKTRUM, Wrocław, Poland
| | - Marek Cwirko
- Ophthalmology Clinical Centre SPEKTRUM, Wrocław, Poland
| | - Zdzislaw Kielbowicz
- Wrocław University of Environmental and Life Sciences, Department of Surgery, Faculty of Veterinary Medicine, Wrocław, Poland
| | - D Robert Iskander
- Wrocław University of Science and Technology, Department of Biomedical Engineering, Wrocław, Poland
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Sobczak M, Asejczyk M, Kalinowski K, Pierścionek B. Comparative analysis of the corneal birefringence pattern in healthy children and adults. Ophthalmic Physiol Opt 2021; 41:715-725. [PMID: 34021615 DOI: 10.1111/opo.12835] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 03/30/2021] [Indexed: 12/17/2022]
Abstract
PURPOSE To undertake a comparative analysis of the corneal shape, thickness and isochromatics in the eyes of children and adults in order to determine the extent of similarities and differences between the cohorts. METHODS The study involved 24 children (aged 8 years) and 37 young White adults (aged between 22-24 years) with no apparent or known health or ocular conditions. Measurements were made of corneal radius of curvature, both central (CCT) and paracentral (PCT) corneal thickness and intraocular pressure (IOP). Images of the isochromatics were captured using a slit lamp and a circular polarizer. The geometry of fringe I and II of the isochromatics was analysed. RESULTS Statistically significant differences were found between CCT and PCT in nasal and temporal regions for both the children and adult cohorts. The same trends were observed in the radii of the cornea. Statistically significant differences between side lengths and angles of isochromatic fringes were found. No differences in asymmetry of shape for fringe I between adults and children were detected; greater symmetry was seen in fringe II in children than for adults. CONCLUSIONS The asymmetry in corneal shape and curvature contributes to the shape of the isochromatic fringes. This is likely linked to the orientation and parameters of the collagen fibres and to the muscles' forces, and be relevant for surgical procedures such as corneal transplantation.
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Affiliation(s)
- Marcelina Sobczak
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Magdalena Asejczyk
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Kamil Kalinowski
- Department of Optics and Photonics, Wroclaw University of Science and Technology, Wrocław, Poland
| | - Barbara Pierścionek
- School of Life Sciences and Education, Staffordshire University, Stoke-on-Trent, UK.,Faculty of Health, Education, Medicine and Social Care, Anglia Ruskin University, Chelmsford, UK
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9
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Niemczyk M, Danielewska ME, Kostyszak MA, Lewandowski D, Iskander DR. The effect of intraocular pressure elevation and related ocular biometry changes on corneal OCT speckle distribution in porcine eyes. PLoS One 2021; 16:e0249213. [PMID: 33770135 PMCID: PMC7997020 DOI: 10.1371/journal.pone.0249213] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/14/2021] [Indexed: 11/21/2022] Open
Abstract
The aim of this study was to evaluate the influence of increase in intraocular pressure (IOP) and cooccurring changes in ocular biometry parameters on the corneal optical coherence tomography (OCT) speckle distribution in ex-vivo experiments on porcine intact eyes. Twenty-three eyeballs were used in the inflation test where IOP in the anterior chamber was precisely set from 10 mmHg to 40 mmHg in steps of 5 mmHg and where eye biometry was utilized (IOL Master 700). To assess the influence of the duration of the experiment on the OCT speckle statistics, the second experiment was performed with 10 eyeballs at the constant IOP of 15 mmHg. Based on the OCT scans of central cornea (Copernicus REVO), spatial maps of the scale parameter (a) and the shape parameter (v) of the gamma distribution speckle model were estimated. The means of both parameters for each spatial map were computed within the 2 mm of the central stroma. Both distributional parameters statistically significantly varied with IOP and time (one way repeated measures ANOVA, all p-values < 0.001). The a parameter revealed a faster statistically significant increase in IOP up to 25 mmHg, regardless of time. Central corneal thickness (CCT), the anterior chamber depth, and the mean equivalent spherical power varied significantly with IOP, whereas CCT and axial length changed statistically significantly with time. Statistically significant correlation was found between CCT and the a parameter, after removing IOP as a confounding factor (r = −0.576, p < 0.001). The parameters of the gamma distribution can be used not only for identifying IOP induced changes in the optical scattering within the corneal stroma, but also in corneal geometry. The approach of corneal speckle analysis could be potentially utilized for an indirect and noninvasive assessment of some properties of corneal stroma.
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Affiliation(s)
- Marcela Niemczyk
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
- * E-mail:
| | - Monika E. Danielewska
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Malgorzata A. Kostyszak
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - Daniel Lewandowski
- Department of Mechanics, Materials and Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
| | - D. Robert Iskander
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw, Poland
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Fang L, Ma W, Wang Y, Dai Y, Fang Z. Theoretical Analysis of Wave-Front Aberrations Induced from Conventional Laser Refractive Surgery in a Biomechanical Finite Element Model. Invest Ophthalmol Vis Sci 2020; 61:34. [PMID: 32433759 PMCID: PMC7405709 DOI: 10.1167/iovs.61.5.34] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To examine the biomechanical effects-induced wave-front aberrations after conventional laser refractive surgery. Methods A finite element model of the human eye was established to simulate conventional laser refractive surgery with corrected refraction from –1 to –15 diopters (D). The deformation of the anterior and posterior corneal surfaces was obtained under the intraocular pressure (IOP). Then, the surface displacement was converted to wave-front aberrations. Results Following conventional refractive surgery, significant deformation of the anterior and posterior corneal surfaces occurred because of the corneal biomechanical effects, resulting in increased residual wave-front aberrations. Deformation of the anterior surface resulted in a hyperopic shift, which was significantly increased with the increasing refractive correction. The residual high-order aberrations consisted of spherical aberration, vertical coma, and y-trefoil. Spherical aberration was significantly positively correlated to enhanced refraction correction. The effect of posterior corneal surface on induced wave-front aberration was less than the anterior corneal surface. The IOP slightly affects the postoperative defocus, coma, and spherical aberration. When treatment decentration occurred during the procedure, the hyperopic shift decreased as the eccentricity increased. Treatment decentration had a significant impact on the spherical aberration and the coma. In addition, the ocular tissue elasticity played a key role in hyperopic shift, whereas it had little effect on the other aberrations. Conclusions Among the many factors that affect high-order aberrations after conventional laser refractive surgery, the alterations in corneal morphology caused by biomechanical effects must be considered, as they can lead to an increase in postoperative residual wave-front aberrations.
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Assessing Corneal Speckle in Optical Coherence Tomography: A New Look at Glaucomatous Eyes. Optom Vis Sci 2020; 97:62-67. [DOI: 10.1097/opx.0000000000001476] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Kazaili A, Geraghty B, Akhtar R. Microscale assessment of corneal viscoelastic properties under physiological pressures. J Mech Behav Biomed Mater 2019; 100:103375. [DOI: 10.1016/j.jmbbm.2019.103375] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 07/21/2019] [Accepted: 07/26/2019] [Indexed: 10/26/2022]
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Lee SL, Chen YF, Dong CY. Second harmonic generation imaging reveals asymmetry in the rotational helicity of collagen lamellae in chicken corneas. BIOMEDICAL OPTICS EXPRESS 2019; 10:5223-5234. [PMID: 31646043 PMCID: PMC6788602 DOI: 10.1364/boe.10.005223] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 09/04/2019] [Accepted: 09/05/2019] [Indexed: 05/03/2023]
Abstract
High tensile strength and optical clarity are unique properties of the cornea. These features are dictated by the three-dimensional architecture of corneal lamellae. Therefore, understanding the microscopic details of the cornea's structural organization may contribute to the development of artificial cornea for the treatment of corneal diseases. In this study, the combination of forward second harmonic generation (SHG) microcopy and fast Fourier-transform based image analysis was used to characterize the depth-dependent superstructure of chicken corneal stroma. Our results show that from the surface, adjacent lamellae of anterior chicken cornea lamella rotate in a counterclockwise direction, and the same rotational helicity is observed in left and right corneas. Furthermore, the overall average rotational pitch of lamellae is 0.92 ± 0.11 degree/µm which persists for 176 ± 14 µm in the anterior stroma. As depth further increased, the rate of lamellar rotation decreases. Upon reaching posterior stroma, lamellar orientation remains constant. Throughout the stroma, collagen lamellae in chicken rotate a total of 169 ± 21 degrees. The lack of lamellar rotation in posterior stroma suggests that packing efficiency cannot be used to explain the helicity of depth-dependent rotation of anterior stroma. In addition, although the right cornea has a higher rotational pitch (0.95 ± 11 vs 0.90 ± 10 degrees/µm) and thinner anterior stroma (173 ± 13 vs 179 ± 14 µm) than the left cornea, the two effects cancel each other out and result in similar total angular rotation of anterior stroma (161 ± 23 and 165 degrees ± 21). Finally, our observation of a total angular rotation of 169 ± 21 degrees shows that within experimental error, chicken cornea lamellae rotate around 180 degrees or half of a complete turn. Additional studies are needed to arrive at an explanation of chicken superstructure in three dimensions.
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Affiliation(s)
- Sheng-Lin Lee
- Department of Physics, National Taiwan University, Taipei 106, Taiwan, China
| | - Yang-Fang Chen
- Department of Physics, National Taiwan University, Taipei 106, Taiwan, China
| | - Chen-Yuan Dong
- Department of Physics, National Taiwan University, Taipei 106, Taiwan, China
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14
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Pitre JJ, Kirby MA, Gao L, Li DS, Shen T, Wang RK, O'Donnell M, Pelivanov I. Super-shear evanescent waves for non-contact elastography of soft tissues. APPLIED PHYSICS LETTERS 2019; 115:083701. [PMID: 32127722 PMCID: PMC7043857 DOI: 10.1063/1.5111952] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/01/2019] [Indexed: 05/12/2023]
Abstract
We describe surface wave propagation in soft elastic media at speeds exceeding the bulk shear wave speed. By linking these waves to the elastodynamic Green's function, we derive a simple relationship to quantify the elasticity of a soft medium from the speed of this supershear evanescent wave (SEW). We experimentally probe SEW propagation in tissue-mimicking phantoms, human cornea ex vivo, and skin in vivo using a high-speed optical coherence elastography system. Measurements confirm the predicted relationship between SEW and bulk shear wave speeds, agreeing well with both theoretical and numerical models. These results suggest that SEW measurements may be a robust method to quantify elasticity in soft media, particularly in complex, bounded materials where dispersive Rayleigh-Lamb modes complicate measurements.
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Affiliation(s)
- John J Pitre
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | - Mitchell A Kirby
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | - Liang Gao
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | | | - Tueng Shen
- Department of Ophthalmology, University of Washington, Seattle, Washington 98104, USA
| | | | - Matthew O'Donnell
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, Washington 98195, USA
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15
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Schmeltz M, Teulon C, Latour G, Ghoubay D, Borderie V, Aimé C, Schanne-Klein MC. Implementation of artifact-free circular dichroism SHG imaging of collagen. OPTICS EXPRESS 2019; 27:22685-22699. [PMID: 31510554 DOI: 10.1364/oe.27.022685] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Second harmonic generation (SHG) enables in situ imaging of fibrillar collagen architecture in connective tissues. Recently, Circular Dichroism SHG (CD-SHG) microscopy has been implemented to take advantage of collagen chirality to improve 3D visualization. It measures the normalized difference in the SHG signal obtained upon excitation by left versus right circular polarizations. However, CD-SHG signal is not well characterized yet, and quite different CD-SHG values are reported in the literature. Here, we identify two major artifacts that may occur in CD-SHG experiments and we demonstrate that thorough optimization and calibration of the experimental setup are required for CD-SHG imaging. Notably it requires a careful calibration of the incident circular polarizations and a perfect mechanical stabilization of the microscope stage. Finally, we successfully record CD-SHG images in human cornea sections and confirm that this technique efficiently reveals collagen fibrils oriented out of the focal plane.
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Ducourthial G, Affagard JS, Schmeltz M, Solinas X, Lopez-Poncelas M, Bonod-Bidaud C, Rubio-Amador R, Ruggiero F, Allain JM, Beaurepaire E, Schanne-Klein MC. Monitoring dynamic collagen reorganization during skin stretching with fast polarization-resolved second harmonic generation imaging. JOURNAL OF BIOPHOTONICS 2019; 12:e201800336. [PMID: 30604478 DOI: 10.1002/jbio.201800336] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Revised: 12/04/2018] [Accepted: 01/02/2019] [Indexed: 06/09/2023]
Abstract
The mechanical properties of biological tissues are strongly correlated to the specific distribution of their collagen fibers. Monitoring the dynamic reorganization of the collagen network during mechanical stretching is however a technical challenge, because it requires mapping orientation of collagen fibers in a thick and deforming sample. In this work, a fast polarization-resolved second harmonic generation microscope is implemented to map collagen orientation during mechanical assays. This system is based on line-to-line switching of polarization using an electro-optical modulator and works in epi-detection geometry. After proper calibration, it successfully highlights the collagen dynamic alignment along the traction direction in ex vivo murine skin dermis. This microstructure reorganization is quantified by the entropy of the collagen orientation distribution as a function of the stretch ratio. It exhibits a linear behavior, whose slope is measured with a good accuracy. This approach can be generalized to probe a variety of dynamic processes in thick tissues.
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Affiliation(s)
| | | | | | - Xavier Solinas
- LOB, École Polytechnique, CNRS, INSERM, Palaiseau, France
| | | | - Christelle Bonod-Bidaud
- Institut de Génomique Fonctionnelle de Lyon, ENS-Lyon, CNRS, Université de Lyon, Lyon, France
| | - Ruth Rubio-Amador
- Institut de Génomique Fonctionnelle de Lyon, ENS-Lyon, CNRS, Université de Lyon, Lyon, France
| | - Florence Ruggiero
- Institut de Génomique Fonctionnelle de Lyon, ENS-Lyon, CNRS, Université de Lyon, Lyon, France
| | - Jean-Marc Allain
- LMS, École Polytechnique, CNRS, Palaiseau, France
- Inria, Université Paris-Saclay, Palaiseau, France
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17
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Zhou D, Eliasy A, Abass A, Markov P, Whitford C, Boote C, Movchan A, Movchan N, Elsheikh A. Analysis of X-ray scattering microstructure data for implementation in numerical simulations of ocular biomechanical behaviour. PLoS One 2019; 14:e0214770. [PMID: 30934028 PMCID: PMC6443175 DOI: 10.1371/journal.pone.0214770] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 03/19/2019] [Indexed: 11/18/2022] Open
Abstract
This study aimed to analyse microstructure data on the density and orientation of collagen fibrils in whole eye globes and to propose an effective method for the preparation of data for use in numerical simulations of the eye’s biomechanical performance. Wide-angle X-ray scattering was applied to seven healthy ex-vivo human eyes. Each eye was dissected into an anterior and a posterior cup, and radial incisions were used to flatten the tissue before microstructure characterisation. A method was developed to use the microstructure data obtained for the dissected tissue to build realistic 3D maps of fibril density and orientation covering the whole eye globe. At the central cornea, 61.5±2.3% of fibrils were aligned within 45° sectors surrounding the two orthogonal directions. In contrast, more than one-third of the total fibril content was concentrated along the circumferential direction at the limbus (37.0±2.4%) and around the optic nerve head (34.8±2.1%). The insertion locations of the four recti muscles exhibited a preference in the meridional direction near the equator (38.6±3.9%). There was also a significant difference in fibril density between the limbus and other regions (ratio = 1.91±0.45, p <0.01 at the central cornea and ratio = 0.80±0.21, p <0.01 at the posterior pole). Characterisation of collagen fibril density and orientation across the whole ocular surface has been possible but required the use of a technique that involved tissue dissection and hence caused tissue damage. The method presented in this paper aimed to minimise the effect of dissection on the quality of obtained data and was successful in identifying fibril distribution trends that were compatible with earlier studies, which concentrated on localised areas of the ocular globe.
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Affiliation(s)
- Dong Zhou
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - Ashkan Eliasy
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Petar Markov
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | | | - Craig Boote
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Alexander Movchan
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Natalia Movchan
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- National Institute for Health Research Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital National Health Service Foundation Trust and University College London Institute of Ophthalmology, London, United Kingdom
- School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
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18
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Abstract
An important issue in tissue biomechanics is to decipher the relationship between the mechanical behavior at macroscopic scale and the organization of the collagen fiber network at microscopic scale. Here, we present a protocol to combine traction assays with multiphoton microscopy in ex vivo murine skin. This multiscale approach provides simultaneously the stress/stretch response of a skin biopsy and the collagen reorganization in the dermis by use of second harmonic generation (SHG) signals and appropriate image processing.
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19
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Fernández J, Rodríguez-Vallejo M, Martínez J, Tauste A, Piñero DP. Corneal biomechanics after laser refractive surgery: Unmasking differences between techniques. J Cataract Refract Surg 2018; 44:390-398. [PMID: 29615281 DOI: 10.1016/j.jcrs.2017.10.054] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 10/02/2017] [Accepted: 10/03/2017] [Indexed: 10/17/2022]
Abstract
The hypothesis that small-incision lenticule extraction provides better preservation of corneal biomechanics than previous laser refractive techniques has led to a growth in the interest in clinical and experimental research in this field. This hypothesis is based on the fact that corneal layers with greater stiffness are preserved with this new technique. However, this hypothesis is controversial because clinical research has shown a great disparity in the outcomes. In this review, we performed an in-depth analysis of the factors that might affect corneal biomechanics in laser refractive surgery procedures from a macrostructural to a microstructural viewpoint. New advances in algorithms with current devices or the introduction of new devices might help unmask the possible advantages of small-incision lenticule extraction in corneal biomechanics.
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Affiliation(s)
- Joaquín Fernández
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - Manuel Rodríguez-Vallejo
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain.
| | - Javier Martínez
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - Ana Tauste
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
| | - David P Piñero
- From the Department of Ophthalmology (Qvision) (Fernández, Rodríguez-Vallejo, Martínez, Tauste), Vithas Virgen del Mar Hospital and the Department of Ophthalmology (Fernández, Piñero), Torrecárdenas Hospital Complex, Almería, and the Department of Optics, Pharmacology and Anatomy (Piñero), University of Alicante, and the Department of Ophthalmology (Piñero), Vithas Medimar International Hospital, Alicante, Spain
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20
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How aging impacts skin biomechanics: a multiscale study in mice. Sci Rep 2017; 7:13750. [PMID: 29061975 PMCID: PMC5653787 DOI: 10.1038/s41598-017-13150-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 09/19/2017] [Indexed: 12/21/2022] Open
Abstract
Skin aging is a complex process that strongly affects the mechanical behavior of skin. This study aims at deciphering the relationship between age-related changes in dermis mechanical behavior and the underlying changes in dermis microstructure. To that end, we use multiphoton microscopy to monitor the reorganization of dermal collagen during mechanical traction assays in ex vivo skin from young and old mice. The simultaneous variations of a full set of mechanical and microstructural parameters are analyzed in the framework of a multiscale mechanical interpretation. They show consistent results for wild-type mice as well as for genetically-modified mice with modified collagen V synthesis. We mainly observe an increase of the tangent modulus and a lengthening of the heel region in old murine skin from all strains, which is attributed to two different origins that may act together: (i) increased cross-linking of collagen fibers and (ii) loss of water due to proteoglycans deterioration, which impedes inner sliding within these fibers. In contrast, the microstructure reorganization upon stretching shows no age-related difference, which can be attributed to opposite effects of the decrease of collagen content and of the increase of collagen cross-linking in old mice.
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21
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Grieve K, Ghoubay D, Georgeon C, Latour G, Nahas A, Plamann K, Crotti C, Bocheux R, Borderie M, Nguyen TM, Andreiuolo F, Schanne-Klein MC, Borderie V. Stromal striae: a new insight into corneal physiology and mechanics. Sci Rep 2017; 7:13584. [PMID: 29051516 PMCID: PMC5648881 DOI: 10.1038/s41598-017-13194-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 09/19/2017] [Indexed: 12/26/2022] Open
Abstract
We uncover the significance of a previously unappreciated structural feature in corneal stroma, important to its biomechanics. Vogt striae are a known clinical indicator of keratoconus, and consist of dark, vertical lines crossing the corneal depth. However we detected stromal striae in most corneas, not only keratoconus. We observed striae with multiple imaging modalities in 82% of 118 human corneas, with pathology-specific differences. Striae generally depart from anchor points at Descemet’s membrane in the posterior stroma obliquely in a V-shape, whereas in keratoconus, striae depart vertically from posterior toward anterior stroma. Optical coherence tomography shear wave elastography showed discontinuity of rigidity, and second harmonic generation and scanning electron microscopies showed undulation of lamellae at striae locations. Striae visibility decreased beyond physiological pressure and increased beyond physiological hydration. Immunohistology revealed striae to predominantly contain collagen VI, lumican and keratocan. The role of these regions of collagen VI linking sets of lamellae may be to absorb increases in intraocular pressure and external shocks.
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Affiliation(s)
- Kate Grieve
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France. .,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France.
| | - Djida Ghoubay
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France.,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
| | | | - Gael Latour
- Laboratoire Imagerie et Modélisation en Neurobiologie et Cancérologie, Univ. Paris-Sud, CNRS, Université Paris-Saclay, Orsay, France
| | | | - Karsten Plamann
- ENSTA ParisTech, Ecole polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | - Caroline Crotti
- ENSTA ParisTech, Ecole polytechnique, CNRS, Université Paris-Saclay, Palaiseau, France
| | | | - Marie Borderie
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France
| | | | | | - Marie-Claire Schanne-Klein
- Laboratoire d'Optique et Biosciences, Ecole polytechnique, CNRS, INSERM U1182,Université Paris-Saclay, Palaiseau, France
| | - Vincent Borderie
- CHNO des Quinze Vingts, INSERM-DHOS CIC 503, Paris, France.,Institut de la Vision, Sorbonne Universités, UPMC Univ Paris 06, INSERM, CNRS, Paris, France
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22
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Biaxial loading of arterial tissues with 3D in situ observations of adventitia fibrous microstructure: A method coupling multi-photon confocal microscopy and bulge inflation test. J Mech Behav Biomed Mater 2017; 74:488-498. [DOI: 10.1016/j.jmbbm.2017.07.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 07/06/2017] [Accepted: 07/18/2017] [Indexed: 12/24/2022]
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23
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Even C, Marlière C, Ghigo JM, Allain JM, Marcellan A, Raspaud E. Recent advances in studying single bacteria and biofilm mechanics. Adv Colloid Interface Sci 2017; 247:573-588. [PMID: 28754382 DOI: 10.1016/j.cis.2017.07.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/18/2017] [Accepted: 07/18/2017] [Indexed: 12/15/2022]
Abstract
Bacterial biofilms correspond to surface-associated bacterial communities embedded in hydrogel-like matrix, in which high cell density, reduced diffusion and physico-chemical heterogeneity play a protective role and induce novel behaviors. In this review, we present recent advances on the understanding of how bacterial mechanical properties, from single cell to high-cell density community, determine biofilm tri-dimensional growth and eventual dispersion and we attempt to draw a parallel between these properties and the mechanical properties of other well-studied hydrogels and living systems.
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24
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Kontenis L, Samim M, Krouglov S, Barzda V. Third-harmonic generation Stokes-Mueller polarimetric microscopy. OPTICS EXPRESS 2017; 25:13174-13189. [PMID: 28788853 DOI: 10.1364/oe.25.013174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 04/27/2017] [Indexed: 05/28/2023]
Abstract
An experimental implementation of the nonlinear Stokes-Mueller polarimetric (NSMP) microscopy in third-harmonic generation modality is presented. The technique is able to extract all eight 2D-accessible χ(3) components for any sample from 64 polarization measurements, and can be applied to noninvasive ultrastructural characterization. The polarization signature of an isotropic glass coverslip is presented, and carotenoid crystallites in the root of orange carrot (Daucus carota) are investigated, showing complex χ(3) components with a significant chiral contribution.
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25
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Jayyosi C, Affagard JS, Ducourthial G, Bonod-Bidaud C, Lynch B, Bancelin S, Ruggiero F, Schanne-Klein MC, Allain JM, Bruyère-Garnier K, Coret M. Affine kinematics in planar fibrous connective tissues: an experimental investigation. Biomech Model Mechanobiol 2017; 16:1459-1473. [DOI: 10.1007/s10237-017-0899-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 03/15/2017] [Indexed: 02/07/2023]
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