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Yang L, Qi K, Zhang P, Cheng J, Soha H, Jin Y, Ci H, Zheng X, Wang B, Mei Y, Chen S, Wang J. Diagnosis of Forme Fruste Keratoconus Using Corvis ST Sequences with Digital Image Correlation and Machine Learning. Bioengineering (Basel) 2024; 11:429. [PMID: 38790296 PMCID: PMC11117575 DOI: 10.3390/bioengineering11050429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 04/07/2024] [Accepted: 04/24/2024] [Indexed: 05/26/2024] Open
Abstract
PURPOSE This study aimed to employ the incremental digital image correlation (DIC) method to obtain displacement and strain field data of the cornea from Corvis ST (CVS) sequences and access the performance of embedding these biomechanical data with machine learning models to distinguish forme fruste keratoconus (FFKC) from normal corneas. METHODS 100 subjects were categorized into normal (N = 50) and FFKC (N = 50) groups. Image sequences depicting the horizontal cross-section of the human cornea under air puff were captured using the Corvis ST tonometer. The high-speed evolution of full-field corneal displacement, strain, velocity, and strain rate was reconstructed utilizing the incremental DIC approach. Maximum (max-) and average (ave-) values of full-field displacement V, shear strain γxy, velocity VR, and shear strain rate γxyR were determined over time, generating eight evolution curves denoting max-V, max-γxy, max-VR, max-γxyR, ave-V, ave-γxy, ave-VR, and ave-γxyR, respectively. These evolution data were inputted into two machine learning (ML) models, specifically Naïve Bayes (NB) and Random Forest (RF) models, which were subsequently employed to construct a voting classifier. The performance of the models in diagnosing FFKC from normal corneas was compared to existing CVS parameters. RESULTS The Normal group and the FFKC group each included 50 eyes. The FFKC group did not differ from healthy controls for age (p = 0.26) and gender (p = 0.36) at baseline, but they had significantly lower bIOP (p < 0.001) and thinner central cornea thickness (CCT) (p < 0.001). The results demonstrated that the proposed voting ensemble model yielded the highest performance with an AUC of 1.00, followed by the RF model with an AUC of 0.99. Radius and A2 Time emerged as the best-performing CVS parameters with AUC values of 0.948 and 0.938, respectively. Nonetheless, no existing Corvis ST parameters outperformed the ML models. A progressive enhancement in performance of the ML models was observed with incremental time points during the corneal deformation. CONCLUSION This study represents the first instance where displacement and strain data following incremental DIC analysis of Corvis ST images were integrated with machine learning models to effectively differentiate FFKC corneas from normal ones, achieving superior accuracy compared to existing CVS parameters. Considering biomechanical responses of the inner cornea and their temporal pattern changes may significantly improve the early detection of keratoconus.
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Affiliation(s)
- Lanting Yang
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Kehan Qi
- Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
- University of Chinese Academy of Sciences, Beijing 101408, China
| | - Peipei Zhang
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Jiaxuan Cheng
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Hera Soha
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Yun Jin
- State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
- International Research Center for Computational Mechanics, Dalian University of Technology, Dalian 116023, China
| | - Haochen Ci
- State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
- International Research Center for Computational Mechanics, Dalian University of Technology, Dalian 116023, China
| | - Xianling Zheng
- State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
- International Research Center for Computational Mechanics, Dalian University of Technology, Dalian 116023, China
| | - Bo Wang
- State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
- International Research Center for Computational Mechanics, Dalian University of Technology, Dalian 116023, China
| | - Yue Mei
- State Key Laboratory of Structural Analysis, Optimization and CAE Software for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, China
- International Research Center for Computational Mechanics, Dalian University of Technology, Dalian 116023, China
| | - Shihao Chen
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
| | - Junjie Wang
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou 325027, China
- Department of Ophthalmology, Sichuan Mental Health Center, Mianyang 621054, China
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Del Barco O, Ávila FJ, Marcellán C, Remón L. Corneal retardation time as an ocular hypertension disease indicator. Biomed Phys Eng Express 2023; 10:015014. [PMID: 38055990 DOI: 10.1088/2057-1976/ad12fa] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 12/06/2023] [Indexed: 12/08/2023]
Abstract
Objective.A detailed analysis of the corneal retardation timeτas a highly related parameter to the intraocular pressure (IOP), and its plausible role as an indicator of ocular hypertension disease.Approach.A simple theoretical expression forτis derived within the corneal viscoelastic model of Kelvin-Voigt with 3 elements. This retardation time can be easily calculated from the well-known signal and pressure amplitudes of non-contact tonometers like the Ocular Response Analyzer (ORA). Then, a population-based study was performed where 100 subjects aged from 18 to 30 were analyzed (within this group, about 10% had an elevated IOP with more than 21 mmHg).Main results.A clear relationship between the corneal retardation time and the corneal-compensated intraocular pressure (IOPcc) was found, underlying the risk for ocular hypertensive (OHT) subjects with lowerτvalues to develop hypertension illnesses (due to the inability of poorly viscoelastic corneas to absorb IOP fluctuations, resulting in probable optic nerve damage).Significance.Our results might provide an useful tool to systematically discern which OHT patients (and even those with normal IOP values) are more likely to suffer glaucoma progression and, consequently, ensure an early diagnosis.
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Affiliation(s)
- Oscar Del Barco
- Laboratorio de Óptica, Instituto Universitario de Investigación en Óptica y Nanofísica, Universidad de Murcia, Campus de Espinardo, E-30100, Murcia, Spain
| | - Francisco J Ávila
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Concepción Marcellán
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
| | - Laura Remón
- Departamento de Física Aplicada, Universidad de Zaragoza, E-50009, Zaragoza, Spain
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3
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Kauppila M, Mörö A, Valle‐Delgado JJ, Ihalainen T, Sukki L, Puistola P, Kallio P, Ilmarinen T, Österberg M, Skottman H. Toward Corneal Limbus In Vitro Model: Regulation of hPSC-LSC Phenotype by Matrix Stiffness and Topography During Cell Differentiation Process. Adv Healthc Mater 2023; 12:e2301396. [PMID: 37449943 PMCID: PMC11468526 DOI: 10.1002/adhm.202301396] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/29/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023]
Abstract
A functional limbal epithelial stem cells (LSC) niche is a vital element in the regular renewal of the corneal epithelium by LSCs and maintenance of good vision. However, little is known about its unique structure and mechanical properties on LSC regulation, creating a significant gap in development of LSC-based therapies. Herein, the effect of mechanical and architectural elements of the niche on human pluripotent derived LSCs (hPSC-LSC) phenotype and growth is investigated in vitro. Specifically, three formulations of polyacrylamide gels with different controlled stiffnesses are used for culture and characterization of hPSC-LSCs from different stages of differentiation. In addition, limbal mimicking topography in polydimethylsiloxane is utilized for culturing hPSC-LSCs at early time point of differentiation. For comparison, the expression of selected key proteins of the corneal cells is analyzed in their native environment through whole mount staining of human donor corneas. The results suggest that mechanical response and substrate preference of the cells is highly dependent on their developmental stage. In addition, data indicate that cells may carry possible mechanical memory from previous culture matrix, both highlighting the importance of mechanical design of a functional in vitro limbus model.
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Affiliation(s)
- Maija Kauppila
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Anni Mörö
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Juan José Valle‐Delgado
- Department of Bioproducts and BiosystemsSchool of Chemical EngineeringAalto UniversityEspoo02150Finland
| | - Teemu Ihalainen
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Lassi Sukki
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Paula Puistola
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Pasi Kallio
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Tanja Ilmarinen
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
| | - Monika Österberg
- Department of Bioproducts and BiosystemsSchool of Chemical EngineeringAalto UniversityEspoo02150Finland
| | - Heli Skottman
- Faculty of Medicine and Health TechnologyTampere UniversityTampere33520Finland
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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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5
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Silver FH, Deshmukh T, Benedetto D, Gonzalez-Mercedes M. Dynamic Ocular Response to Mechanical Loading: The Role of Viscoelasticity in Energy Dissipation by the Cornea. Biomimetics (Basel) 2023; 8:63. [PMID: 36810394 PMCID: PMC9944807 DOI: 10.3390/biomimetics8010063] [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: 12/23/2022] [Revised: 01/26/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
We have used vibrational optical coherence tomography (VOCT) to measure the resonant frequency, elastic modulus, and loss modulus of components of the anterior segment of pig eyes in vitro. Such basic biomechanical properties of the cornea have been shown to be abnormal not only in diseases of the anterior segment but also in posterior segment diseases as well. This information is needed to better understand corneal biomechanics in health and disease and to be able to diagnose the early stages of corneal pathologies. Results of dynamic viscoelastic studies on whole pig eyes and isolated corneas indicate that at low strain rates (30 Hz or less), the viscous loss modulus is as high as 0.6 times the elastic modulus for both whole eyes and corneas. This large viscous loss is similar to that of skin, which has been hypothesized to be dependent upon the physical association of proteoglycans with collagenous fibers. The energy dissipation properties of the cornea provide a mechanism to dissipate energy associated with blunt trauma, thereby preventing delamination and failure. The cornea possesses the ability to store impact energy and transmit excess energy to the posterior segment of the eye through its serial connection to the limbus and sclera. In this manner, the viscoelastic properties of the cornea, in concert with that of the posterior segment of the pig eye, function to prevent mechanical failure of the primary focusing element of the eye. Results of resonant frequency studies suggest that the 100-120 Hz and 150-160 Hz resonant frequency peaks reside in the anterior segment of the cornea since the removal of the anterior segment of the cornea decreases the peak heights at these resonant frequencies. These results suggest that there is more than one collagen fibril network found in the anterior portion of the cornea that provides structural integrity to prevent corneal delamination and that VOCT may be useful clinically to diagnose corneal diseases.
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Affiliation(s)
- Frederick H. Silver
- Department of Pathology and Laboratory Medicine, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- OptoVibronex, LLC, Ben Franklin Tech Partners, Bethlehem, PA 18015, USA
| | - Tanmay Deshmukh
- OptoVibronex, LLC, Ben Franklin Tech Partners, Bethlehem, PA 18015, USA
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6
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Wang B, Yang L, Cheng J, Wang J, Mei Y. In-vivo high-speed biomechanical imaging of the cornea using Corvis ST and digital image correlation. Comput Biol Med 2023; 153:106540. [PMID: 36646022 DOI: 10.1016/j.compbiomed.2023.106540] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 12/16/2022] [Accepted: 01/10/2023] [Indexed: 01/12/2023]
Abstract
In-vivo corneal biomechanical characterization has gained significant clinical relevance in ophthalmology, especially in the early diagnosis of eye disorders and diseases (e.g. keratoconus). In clinical medicine, the air-puff-based tonometers such as Ocular Response Analyzer (ORA) and Corvis ST have been used in the in-vivo biomechanical testing. In the test, the high-speed dynamic deformation of the cornea under air-puff excitation is analyzed to identify the abnormities in the morphological and biomechanical properties of the cornea. While most existing measurements reflect the overall corneal biomechanical properties, in-vivo high-speed strain and strain rate fields at the tissue level have not been assessed. In this study, 20 subjects were classified into two different groups: the normal (NORM, N = 10) group and the keratoconus (KC, N = 10) group. Image sequences of the horizontal cross-section of the human cornea under air puff were captured by the Corvis ST tonometer. The macroscale mechanical response of the cornea was determined through image analysis. The high-speed evolution of full-field corneal displacement, strain, velocity, and strain rate was reconstructed using the incremental digital image correlation (DIC) approach. Differences in the parameters between the NORM and KC groups were statistically analyzed and compared. Statistical results indicated that compared with the NORM group, the KC corneas absorbed more energy (KC: 8.98 ± 2.76 mN mm; NORM: 4.79 ± 0.62 mN mm; p-value <0.001) with smaller tangent stiffness (KC: 22.49 ± 2.62 mN/mm; NORM: 24.52 ± 3.20 mN/mm; p-value = 0.15) and larger maximum deflection (KC: 0.99 ± 0.07 mN/mm; NORM: 0.92 ± 0.06 mN/mm; p-value <0.05) on the macro scale. Further, we also observed that The maximum displacement (KC: 1.17 ± 0.06 mm; NORM: 1.06 ± 0.07 mm; p-value <0.005), velocity (KC: 236 ± 29 mm/s; NORM: 203 ± 17 mm/s; p-value <0.01), shear strain (KC: 24.43 ± 2.59%; NORM: 20.26 ± 1.54%; p-value <0.001), and shear strain rate (KC: 69.74 ± 11.99 s-1; NORM: 54.84 ± 3.03 s-1; p-value <0.005) in the KC group significantly increased at the tissue level. This is the first time that the incremental DIC method was applied to the in-vivo high-speed corneal deformation measurement in combination with the Corvis ST tonometer. Through the image registration using incremental DIC analysis, spatiotemporal dynamic strain/strain rate maps of the cornea can be estimated at the tissue level. This is constructive for the clinical recognition and diagnosis of keratoconus at a more underlying level.
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Affiliation(s)
- Bo Wang
- State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, 116023, PR China; International Research Center for Computational Mechanics, Dalian University of Technology, Dalian, 116023, PR China; Ningbo Institute of Dalian University of Technology, Ningbo, 315016, PR China; DUT-BSU Joint Institute, Dalian University of Technology, 116023, PR China
| | - Lanting Yang
- Eye Hospital, Wenzhou Medical University, Wenzhou, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China
| | - Jiaxuan Cheng
- Eye Hospital, Wenzhou Medical University, Wenzhou, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China
| | - Junjie Wang
- Eye Hospital, Wenzhou Medical University, Wenzhou, China; The Institution of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China.
| | - Yue Mei
- State Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian, 116023, PR China; International Research Center for Computational Mechanics, Dalian University of Technology, Dalian, 116023, PR China; Ningbo Institute of Dalian University of Technology, Ningbo, 315016, PR China; DUT-BSU Joint Institute, Dalian University of Technology, 116023, PR China.
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7
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McAuley R, Nolan A, Curatolo A, Alexandrov S, Zvietcovich F, Varea Bejar A, Marcos S, Leahy M, Birkenfeld JS. Co-axial acoustic-based optical coherence vibrometry probe for the quantification of resonance frequency modes in ocular tissue. Sci Rep 2022; 12:18834. [PMID: 36336702 PMCID: PMC9637745 DOI: 10.1038/s41598-022-21978-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/07/2022] [Indexed: 11/08/2022] Open
Abstract
We present a co-axial acoustic-based optical coherence vibrometry probe (CoA-OCV) for vibro-acoustic resonance quantification in biological tissues. Sample vibrations were stimulated via a loudspeaker, and pre-compensation was used to calibrate the acoustic spectrum. Sample vibrations were measured via phase-sensitive swept-source optical coherence tomography (OCT). Resonance frequencies of corneal phantoms were measured at varying intraocular pressures (IOP), and dependencies on Young´s Modulus (E), phantom thickness and IOP were observed. Cycling IOP revealed hysteresis. For E = 0.3 MPa, resonance frequencies increased with IOP at a rate of 3.9, 3.7 and 3.5 Hz/mmHg for varied thicknesses and 1.7, 2.5 and 2.8 Hz/mmHg for E = 0.16 MPa. Resonance frequencies increased with thickness at a rate of 0.25 Hz/µm for E = 0.3 MPa, and 0.40 Hz/µm for E = 0.16 MPa. E showed the most predominant impact in the shift of the resonance frequencies. Full width at half maximum (FWHM) of the resonance modes increased with increasing thickness and decreased with increasing E. Only thickness and E contributed to the variance of FWHM. In rabbit corneas, resonance frequencies of 360-460 Hz were observed. The results of the current study demonstrate the feasibility of CoA-OCV for use in future OCT-V studies.
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Affiliation(s)
- Ryan McAuley
- Tissue Optics and Microcirculation Imaging Facility, School of Physics, University of Galway, Galway, Ireland.
| | - A Nolan
- Tissue Optics and Microcirculation Imaging Facility, School of Physics, University of Galway, Galway, Ireland
| | - A Curatolo
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
- International Centre for Translational Eye Research, Warsaw, Poland
| | - S Alexandrov
- Tissue Optics and Microcirculation Imaging Facility, School of Physics, University of Galway, Galway, Ireland
| | - F Zvietcovich
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - A Varea Bejar
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
| | - S Marcos
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain
- Center for Visual Science, The Institute of Optics, Flaum Eye Institute, University of Rochester, Rochester, New York, USA
| | - M Leahy
- Tissue Optics and Microcirculation Imaging Facility, School of Physics, University of Galway, Galway, Ireland
| | - J S Birkenfeld
- Instituto de Óptica, Consejo Superior de Investigaciones Científicas (IO-CSIC), Madrid, Spain.
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Li W, Feng J, Wang Y, Shi Q, Ma G, Aglyamov S, Larin KV, Lan G, Twa M. Micron-scale hysteresis measurement using dynamic optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2022; 13:3021-3041. [PMID: 35774312 PMCID: PMC9203113 DOI: 10.1364/boe.457617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/11/2022] [Accepted: 04/14/2022] [Indexed: 05/28/2023]
Abstract
We present a novel optical coherence elastography (OCE) method to characterize mechanical hysteresis of soft tissues based on transient (milliseconds), low-pressure (<20 Pa) non-contact microliter air-pulse stimulation and micrometer-scale sample displacements. The energy dissipation rate (sample hysteresis) was quantified for soft-tissue phantoms (0.8% to 2.0% agar) and beef shank samples under different loading forces and displacement amplitudes. Sample hysteresis was defined as the loss ratio (hysteresis loop area divided by the total loading energy). The loss ratio was primarily driven by the sample unloading response which decreased as loading energy increased. Samples were distinguishable based on their loss ratio responses as a function loading energy or displacement amplitude. Finite element analysis and mechanical testing methods were used to validate these observations. We further performed the OCE measurements on a beef shank tissue sample to distinguish the muscle and connective tissue components based on the displacement and hysteresis features. This novel, noninvasive OCE approach has the potential to differentiate soft tissues by quantifying their viscoelasticity using micron-scale transient tissue displacement dynamics. Focal tissue hysteresis measurements could provide additional clinically useful metrics for guiding disease diagnosis and tissue treatment responses.
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Affiliation(s)
- Wenjie Li
- Foshan University, School of Mechatronic Engineering and Automation, Foshan, Guangdong, 528000, China
- Contributed equally
| | - Jinping Feng
- Hubei University of Science and Technology, Institute of Engineering and Technology, Xianning, Hubei, 437100, China
- Contributed equally
| | - Yicheng Wang
- Foshan University, School of Mechatronic Engineering and Automation, Foshan, Guangdong, 528000, China
| | - Qun Shi
- Foshan University, School of Mechatronic Engineering and Automation, Foshan, Guangdong, 528000, China
| | - Guoqin Ma
- Foshan University, School of Mechatronic Engineering and Automation, Foshan, Guangdong, 528000, China
| | - Salavat Aglyamov
- University of Houston, Mechanical Engineering, Houston, TX 77204, USA
| | - Kirill V Larin
- University of Houston, Biomedical Engineering, Houston, TX 77204, USA
| | - Gongpu Lan
- Foshan University, School of Physics and Optoelectronic Engineering, Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology, Foshan, Guangdong 528000, China
- Innovation and Entrepreneurship Team of Guangdong Pearl River Talents Program, Weiren Meditech Co., Ltd., Foshan, Guangdong, 528000, China
| | - Michael Twa
- University of Houston, College of Optometry, Houston, TX 77204, USA
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Singh M, Zvietcovich F, Larin KV. Introduction to optical coherence elastography: tutorial. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2022; 39:418-430. [PMID: 35297425 PMCID: PMC10052825 DOI: 10.1364/josaa.444808] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Accepted: 01/25/2022] [Indexed: 06/03/2023]
Abstract
Optical coherence elastography (OCE) has seen rapid growth since its introduction in 1998. The past few decades have seen tremendous advancements in the development of OCE technology and a wide range of applications, including the first clinical applications. This tutorial introduces the basics of solid mechanics, which form the foundation of all elastography methods. We then describe how OCE measurements of tissue motion can be used to quantify tissue biomechanical parameters. We also detail various types of excitation methods, imaging systems, acquisition schemes, and data processing algorithms and how various parameters associated with each step of OCE imaging can affect the final quantitation of biomechanical properties. Finally, we discuss the future of OCE, its potential, and the next steps required for OCE to become an established medical imaging technology.
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Affiliation(s)
- Manmohan Singh
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
| | - Fernando Zvietcovich
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
- Department of Engineering, Pontificia Universidad Catolica del Peru, San Miguel, Lima 15088, Peru
| | - Kirill V. Larin
- Biomedical Engineering, University of Houston, Houston, Texas 77204, USA
- Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas 77030, USA
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Ma J, Wang Y, Li M, Jhanji V. Association Between Severity of Myopia and Deformation Characteristics of the Cornea Based on Propensity Score Matching Analysis. J Refract Surg 2021; 37:344-350. [PMID: 34044695 DOI: 10.3928/1081597x-20210222-02] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the relationship between severity of myopia and corneal deformation characteristics after removing confounding factors using propensity score matching (PSM) analysis. METHODS A prospective study was conducted from April 1 to December 30, 2019 in Tianjin Eye Hospital. Participants were divided into low (spherical equivalent [SE] > -6.00 diopters) and high (SE ⩽ -6.00 diopters) myopia groups. Corneal deformation parameters were obtained using corneal visualization Scheimpflug technology. PSM analysis was conducted to minimize the effect of confounding factors (age, intraocular pressure, and corneal thickness) on corneal deformation. Correlation analysis and logistic regression models were applied to investigate the relationships between SE and corneal deformation parameters. RESULTS A total of 2,126 eyes from 1,063 patients with a mean age of 23.81 ± 5.68 years were enrolled. The left and right eyes were analyzed separately. After PSM analysis, logistic regression indicated that the peak distance was a significant indicator for high myopia in both eye models (left: odds ratio [OR] = 1.978, 95% CI: 1.303 to 3.004; right: OR = 2.089, 95% CI: 1.362 to 3.202; P < .001). The maximum amplitudes of deformation and deflection and peak distance were significantly negatively correlated with SE in both eyes, whereas the whole eye movement was significantly positively correlated with SE (P < .01), as well as the deformation amplitude at the second applanation (P < .001). CONCLUSIONS Eyes with high myopia exhibited larger deformation and deflection amplitude compared to eyes with low myopia. The high distance between bending points of the cornea at the highest concavity (peak distance) may be a feature of high myopia. [J Refract Surg. 2021;37(5):344-350.].
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11
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Advances in Imaging Technology of Anterior Segment of the Eye. J Ophthalmol 2021; 2021:9539765. [PMID: 33688432 PMCID: PMC7925029 DOI: 10.1155/2021/9539765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 02/05/2021] [Accepted: 02/16/2021] [Indexed: 12/27/2022] Open
Abstract
Advances in imaging technology and computer science have allowed the development of newer assessment of the anterior segment, including Corvis ST, Brillouin microscopy, ultrahigh-resolution optical coherence tomography, and artificial intelligence. They enable accurate and precise assessment of structural and biomechanical alterations associated with anterior segment disorders. This review will focus on these 4 new techniques, and a brief overview of these modalities will be introduced. The authors will also discuss the recent advances in research regarding these techniques and potential application of these techniques in clinical practice. Many studies on these modalities have reported promising results, indicating the potential for more detailed comprehensive understanding of the anterior segment tissues.
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Wang X, McAlinden C, Zhang H, Yan J, Wang D, Wei W, Mi S. Assessment of corneal biomechanics, tonometry and pachymetry with the Corvis ST in myopia. Sci Rep 2021; 11:3041. [PMID: 33542296 PMCID: PMC7862660 DOI: 10.1038/s41598-020-80915-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/16/2020] [Indexed: 11/09/2022] Open
Abstract
To evaluate the repeatability of Corvis ST corneal biomechanical, tonometry and pachymetry measurements, and agreement of pachymetry measures with the Pentacam HR and RTVue OCT. Three consecutive measurements of the right eye of 238 myopic subjects were acquired with the Corvis ST, Pentacam HR, and RTVue OCT. Repeatability of Corvis ST was evaluated by within-subject standard deviation [Sw] and repeatability limit [r]. The agreement of central corneal thickness (CCT) measurements were compared among the three instruments using the Bland-Altman limits of agreement. Comparisons were further stratified by CCT (Corneathin ≤ 500 µm; Corneanormal = 500-550 µm; Corneathick > 550 µm). Sw was below 1 mmHg in Corneathin, Corneanormal, and Corneathick groups for IOP and bIOP. Sw for SP-A1 were 4.880, 6.128, 7.719 mmHg/mm respectively. Sw for CBI were 0.228, 0.157, 0.076, and correspondingly Sw for TBI and SSI were 0.094 and 0.056, 0.079 and 0.053, 0.070 and 0.053. The Bland-Altman plots for CCT implied poor agreement with mean differences of 29.49 µm between Corvis and OCT, 9.33 µm between Pentacam and OCT, and 20.16 µm between Corvis and Pentacam. The Corvis ST showed good repeatability with the exception of CBI in the various CCT groups. The CCT measured by Corvis ST was not interchangeable with Pentacam HR and RTVue OCT.
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Affiliation(s)
- Xiaorui Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.,Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Colm McAlinden
- Department of Ophthalmology, Singleton Hospital, Swansea Bay University Health Board, Swansea, UK
| | - Hongbing Zhang
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China.,Shaanxi Institute of Ophthalmology, Xi'an, China
| | - Jie Yan
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Dan Wang
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China
| | - Wei Wei
- Laser Vision Center, The First Affiliated Hospital of Northwestern University, No. 30, Fenxiang Alley, Xi'an, Shaanxi, China. .,Shaanxi Institute of Ophthalmology, Xi'an, China.
| | - Shengjian Mi
- Department of Ophthalmology, The First Affiliated Hospital of Xi'an Jiaotong University, No. 277, West Yanta Road, Xi'an, Shaanxi, China.
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Francis M, Matalia H, Nuijts RMMA, Haex B, Shetty R, Sinha Roy A. Corneal Viscous Properties Cannot Be Determined From Air-Puff Applanation. J Refract Surg 2019; 35:730-736. [PMID: 31710375 DOI: 10.3928/1081597x-20191010-03] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/10/2019] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess whether corneal viscous properties are measureable with air-puff applanation in patients. METHODS The study had 312 normal eyes, 107 fellow eyes of patients with keratoconus, and 289 keratoconic eyes. The Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) deformation data for all eyes were analyzed using two models. First, a standard linear solid model (SLM) assumed the cornea was an elastic material only. Second, a two-compartment Kelvin-Voigt model (KVM) assumed the cornea was a visco-elastic material. Corneal stiffness and viscosity were calculated. Further, the deflection amplitude was phase shifted virtually relative to the air-puff applanation force to assess whether the KVM was capable of detecting corneal viscous properties from air-puff applanation. This was similar in concept to measured viscoelastic deformations in other soft tissues. The hysteresis area was also calculated with deformation (cornea and whole globe) and deflection (cornea only) amplitude. The greater the magnitude of the hysteresis area, the greater was the magnitude of corneal viscosity (µc). RESULTS Both the SLM and KVM reported similar magnitudes of corneal stiffnesses (correlation coefficient > 0.99). However, for a given model, corneal stiffness was significantly different between normal, fellow, and keratoconic eyes (P = .001). From the KVM, the corneal viscosity was different between groups (P = .001) but was small in magnitude (order of 10-9). The deflection hysteresis area was also small in magnitude (order of 10-6). In contrast, the KVM detected significant corneal viscosity only when the deflection amplitude was virtually phase shifted with respect to the air-puff applanation force. CONCLUSIONS No significant corneal viscous response was detected in patients who had air-puff applanation. [J Refract Surg. 2019;35(11):730-736.].
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Larin KV, Scarcelli G, Yakovlev VV. Optical elastography and tissue biomechanics. JOURNAL OF BIOMEDICAL OPTICS 2019; 24:1-9. [PMID: 31758675 PMCID: PMC6873628 DOI: 10.1117/1.jbo.24.11.110901] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 10/31/2019] [Indexed: 05/18/2023]
Abstract
Mechanical forces play an important role in the behavior and development of biological systems and disease at all spatial scales, from cells and their constituents to tissues and organs. Such forces have a profound influence on the health, structural integrity, and normal function of cells and organs. Accurate knowledge of cell and tissue biomechanical properties is essential to map the distribution of forces and mechanical cues in biological systems. Cell and tissue biomechanical properties are also known to be important on their own as indicators of health or diseases state. Hence, optical elastography and biomechanics methods can aid in the understanding and clinical diagnosis of a wide variety of diseases. We provide a brief overview and highlight of the Optical Elastography and Tissue Biomechanics VI conference, which took place in San Francisco, February 2 and 3, 2019, as a part of Photonics West symposium.
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Affiliation(s)
- Kirill V. Larin
- University of Houston, Department of Biomedical Engineering, Houston, Texas, United States
| | - Giuliano Scarcelli
- University of Maryland, Department of Biomedical Engineering, College Park, Maryland, United States
| | - Vladislav V. Yakovlev
- Texas A&M University, Department of Biomedical Engineering, College Station, Texas, United States
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Maczynska E, Rzeszewska-Zamiara J, Jimenez Villar A, Wojtkowski M, Kaluzny BJ, Grulkowski I. Air-Puff-Induced Dynamics of Ocular Components Measured with Optical Biometry. Invest Ophthalmol Vis Sci 2019; 60:1979-1986. [PMID: 31050724 DOI: 10.1167/iovs.19-26681] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To analyze the dynamics of all optical components of the eye and the behavior of the eyeball under air-puff conditions in vivo. To determine the impact of the intraocular pressure (IOP) on the air-puff-induced deformation of the eye. Methods Twenty eyes of 20 healthy subjects were included in this study. The dynamics of the ocular components, such as the cornea, the crystalline lens, and the retina, was measured by a prototype swept source optical coherence tomography biometer integrated with the air-puff system. The system allows to acquire a series of axial scans at the same location as a function of time with no transverse scanning. Several parameters were extracted from optical coherence tomography data. The IOP was measured using a Goldmann applanation tonometry. The measurements of the eyes were performed before and 2 hours after administration of IOP-reducing drops, namely, 0.2 % brimonidine tartrate. Results There is a statistically significant correlation of corneal thickness, vitreous depth, and eye length with IOP. The deformation amplitudes of the cornea and the crystalline lens are inversely proportional to the IOP, but statistical significance is achieved only for the cornea. The crystalline lens is displaced without compression, and the return has the form of wobbling. The reduction of IOP level induces corresponding changes in the extracted parameters. Conclusions Optical biometry combined with air puff provides comprehensive information on the in vivo behavior of all ocular components, including the crystalline lens. Measurement of the axial length dynamics of during deformation enables correcting the deformation for eye retraction.
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Affiliation(s)
- Ewa Maczynska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
| | - Jagoda Rzeszewska-Zamiara
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Alfonso Jimenez Villar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland.,Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Bartlomiej J Kaluzny
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, Bydgoszcz, Poland
| | - Ireneusz Grulkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Torun, Poland
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Jiménez-villar A, Mączyńska E, Cichański A, Wojtkowski M, Kałużny BJ, Grulkowski I. High-speed OCT-based ocular biometer combined with an air-puff system for determination of induced retraction-free eye dynamics. BIOMEDICAL OPTICS EXPRESS 2019; 10:3663-3680. [PMID: 31467798 PMCID: PMC6706022 DOI: 10.1364/boe.10.003663] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 06/16/2019] [Accepted: 06/16/2019] [Indexed: 05/20/2023]
Abstract
We demonstrate a swept source OCT-based ocular biometer integrated with an air-puff stimulus to study the reaction of the eye to mechanical stimulation in vivo. The system enables simultaneous measurement of the stimulus strength and high-speed imaging of the eye dynamics along the visual axis. We characterize the stimulus and perform optimization of the data acquisition for a proper interpretation of the results. Access to the dynamics of axial eye length allows for a determination of the eye retraction, which is used to correct the air-puff induced displacement of ocular structures. We define the parameters to quantify the reaction of the eye to the air puff and determine their reproducibility in a group of healthy subjects. We observe the corneal deformation process and axial wobbling of the crystalline lens. OCT biometer combined with the air puff is the first instrument with the potential to provide comprehensive information on the biomechanics of ocular components.
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Affiliation(s)
- Alfonso Jiménez-villar
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
| | - Ewa Mączyńska
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
| | - Artur Cichański
- Institute of Mechanics and Machine Design, Faculty of Mechanical Engineering, UTP University of Science and Technology, Al. Prof. S. Kaliskiego 7, 85-796 Bydgoszcz, Poland
| | - Maciej Wojtkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
- Institute of Physical Chemistry, Polish Academy of Sciences, ul. Kasprzaka 44/52, 01-224 Warsaw, Poland
| | - Bartłomiej J. Kałużny
- Division of Ophthalmology and Optometry, Department of Ophthalmology, Collegium Medicum, Nicolaus Copernicus University, ul. Ujejskiego 75, 85-168 Bydgoszcz, Poland
| | - Ireneusz Grulkowski
- Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, ul. Grudziądzka 5, 87-100 Toruń, Poland
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