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Gong Z, Bojikian KD, Chen A, Chen PP, Rezaei KA, Olmos LC, Mudumbai RC, Li J, Schwartz DM, Wang RK. In-vivo characterization of scleral rigidity in myopic eyes using fundus-pulsation optical coherence elastography. BIOMEDICAL OPTICS EXPRESS 2024; 15:3426-3440. [PMID: 38855699 PMCID: PMC11161338 DOI: 10.1364/boe.523835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/19/2024] [Accepted: 04/21/2024] [Indexed: 06/11/2024]
Abstract
The sclera plays an important role in the structural integrity of the eye. However, as myopia progresses, the elongation of the eyeball exerts stretching forces on the posterior sclera, which typically happens in conjunction with scleral remodeling that causes rigidity loss. These biomechanical alterations can cause localized eyeball deformation and vision impairment. Therefore, monitoring scleral rigidity is clinically important for the management and risk assessment of myopia. In this study, we propose fundus pulsation optical coherence elastography (FP-OCE) to characterize posterior scleral rigidity in living humans. This methodology is based on a choroidal pulsation model, where the scleral rigidity is inversely associated with the choroidal max strain obtained through phase-sensitive optical coherence tomography (PhS-OCT) measurement of choroidal deformation and thickness. Using FP-OCE, we conducted a pilot clinical study to explore the relationship between choroidal strain and myopia severity. The results revealed a significant increase in choroidal max strain in pathologic myopia, indicating a critical threshold beyond which scleral rigidity decreases significantly. Our findings offer a potential new method for monitoring myopia progression and evaluating therapies that alter scleral mechanical properties.
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Affiliation(s)
- Zhaoyu Gong
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | | | - Andrew Chen
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Philip P. Chen
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Kasra A. Rezaei
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Lisa C. Olmos
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Raghu C. Mudumbai
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Jonathan Li
- Department of Ophthalmology, University of California, San Francisco, CA, USA
| | - Daniel M. Schwartz
- Department of Ophthalmology, University of California, San Francisco, CA, USA
- Merkin Institute for Translational Research, California Institute of Technology, Pasadena, CA 91125, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
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Guo X, Li X, Wang X, Li M, Dai X, Kong L, Hao Q, Zhao J, Huang Y, Sun L. Wearable optical coherence tomography angiography probe for freely moving mice. BIOMEDICAL OPTICS EXPRESS 2023; 14:6509-6520. [PMID: 38420312 PMCID: PMC10898568 DOI: 10.1364/boe.506513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/22/2023] [Accepted: 11/22/2023] [Indexed: 03/02/2024]
Abstract
Optical coherence tomography (OCT) is an emerging optical imaging technology that holds great potential in medical and biological applications. Apart from its conventional ophthalmic uses, it has found extensive applications in studying various brain activities and disorders in anesthetized/restricted rodents, with a particular focus on visualizing brain blood vessel morphology and function. However, developing a compact wearable OCT probe for studying the brain activity/disorders in freely moving rodents is challenging due to the requirements for stability and lightweight design. Here, we report a robust wearable OCT probe, which, to the best of our knowledge, is the first wearable OCT angiography probe capable of long-term monitoring of mouse brain blood flow. This wearable imaging probe has a maximum scanning speed of 76 kHz, with a 12 µm axial resolution, 5.5 µm lateral resolution, and a large field of view (FOV) of 4 mm × 4 mm. It offers easy assembly and stable imaging, enabling it to capture brain vessels in freely moving rodents. We tested this probe to monitor cerebral hemodynamics for up to 4 hours during the acute ischemic phase after photothrombotic stroke in mice, highlighting the reliability and long-term stability of our probe. This work contributes to the advancement of wearable biomedical imaging.
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Affiliation(s)
- Xiangyu Guo
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Xiaochen Li
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Xinyue Wang
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Mingxin Li
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Xiaochuan Dai
- Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lingjie Kong
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
| | - Qun Hao
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Jingjing Zhao
- Department of Structural Biology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA
| | - Yong Huang
- School of Optics and Photonics, Beijing Institute of Technology, No. 5 South Zhongguancun Street, Haidian, Beijing 100081, China
| | - Liqun Sun
- State Key Laboratory of Precision Measurement Technology and Instruments, Department of Precision Instrument, Tsinghua University, Beijing 100084, China
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Regnault G, Kirby MA, Wang RK, Shen TT, O’Donnell M, Pelivanov I. Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography. BIOMEDICAL OPTICS EXPRESS 2023; 14:5005-5021. [PMID: 37791258 PMCID: PMC10545180 DOI: 10.1364/boe.497970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 10/05/2023]
Abstract
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (AµT) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from ∼100 µm in the periphery to ∼150 µm in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
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Affiliation(s)
- Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Tueng T. Shen
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
- School of Medicine, University of Washington, Seattle, WA, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, WA, USA
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Regnault G, Kirby MA, Wang RK, Shen TT, O’Donnell M, Pelivanov I. Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography. ARXIV 2023:arXiv:2306.15018v1. [PMID: 37426451 PMCID: PMC10327230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 07/11/2023]
Abstract
Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (A$\mu$T) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from $\sim 100\mu m$ in the periphery to $\sim 150\mu m$ in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
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Affiliation(s)
- Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, USA
- Department of Ophthalmology, University of Washington, Seattle, USA
| | - Tueng T. Shen
- Department of Ophthalmology, University of Washington, Seattle, USA
- School of Medicine, University of Washington, Seattle, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, USA
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Kirby MA, Regnault G, Pelivanov I, O'Donnell M, Wang RK, Shen TT. Noncontact Acoustic Micro-Tapping Optical Coherence Elastography for Quantification of Corneal Anisotropic Elasticity: In Vivo Rabbit Study. Transl Vis Sci Technol 2023; 12:15. [PMID: 36930138 PMCID: PMC10036949 DOI: 10.1167/tvst.12.3.15] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023] Open
Abstract
Purpose The purpose of this study was to demonstrate accurate measurement of corneal elastic moduli in vivo with noncontact and noninvasive optical coherence elastography. Methods Elastic properties (in-plane Young's modulus, E, and both in-plane, μ, and out-of-plane, G, shear moduli) of rabbit cornea were quantified in vivo using noncontact dynamic acoustic micro-tapping optical coherence elastography (AµT-OCE). The intraocular pressure (IOP)-dependence of measured mechanical properties was explored in extracted whole globes following in vivo measurement. A nearly incompressible transverse isotropic (NITI) model was used to reconstruct moduli from AµT-OCE data. Independently, cornea elastic moduli were also measured ex vivo with traditional, destructive mechanical tests (tensile extensometry and shear rheometry). Results Our study demonstrates strong anisotropy of corneal elasticity in rabbits. The in-plane Young's modulus, computed as E = 3μ, was in the range of 20 MPa to 44 MPa, whereas the out-of-plane shear modulus was in the range of 34 kPa to 261 kPa. Both pressure-dependent ex vivo OCE and destructive mechanical tests performed on the same samples within an hour of euthanasia strongly support the results of AµT-OCE measurements. Conclusions Noncontact AµT-OCE can noninvasively quantify cornea anisotropic elastic properties in vivo. Translational Relevance As optical coherence tomography (OCT) is broadly accepted in ophthalmology, these results suggest the potential for rapid translation of AµT-OCE into clinical practice. In addition, AµT-OCE can likely improve diagnostic criteria of ectatic corneal diseases, leading to early diagnosis, reduced complications, customized surgical treatment, and personalized biomechanical models of the eye.
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Affiliation(s)
- Mitchell A Kirby
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Matthew O'Donnell
- Department of Bioengineering, University of Washington, Seattle, WA, USA
| | - Ruikang K Wang
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Tueng T Shen
- School of Medicine, University of Washington, Seattle, WA, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
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Kirby MA, Regnault G, Pelivanov I, O’Donnell M, Wang RK, Shen TT. Non-contact acoustic micro-tapping optical coherence elastography for quantification of corneal anisotropic elasticity: in vivo rabbit study. ARXIV 2023:2301.10652. [PMID: 36748003 PMCID: PMC9900963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE To demonstrate accurate measurement of corneal elastic moduli in vivo with non-contact and non-invasive optical coherence elastography. METHODS Elastic properties (in-plane Young's modulus E and both in-plane, u, and out-of-plane, G, shear moduli) of rabbit cornea were quantified in vivo using non-contact dynamic Acoustic micro-Tapping Optical Coherence Elastography (AuT-OCE). The IOP-dependence of measured mechanical properties was explored in extracted whole globes following in vivo measurement. A nearly-incompressible transverse isotropic (NITI) model was used to reconstruct moduli from AuT-OCE data. Independently, cornea elastic moduli were also measured ex vivo with traditional, destructive mechanical tests (tensile extensometry and shear rheometry). RESULTS Our study demonstrates strong anisotropy of corneal elasticity in rabbits. The in-plane Young's modulus, computer as E=3u, was in the range of 20-44 MPa, whereas the out-of-plane shear modulus was in the range of 34-261 kPa. Both pressure-dependent ex vivo OCE and destructive mechanical tests performed on the same samples within an hour of euthanasia strongly support the results of AuT-OCE measurements. CONCLUSIONS Non-contact AuT-OCE can non-invasively quantify cornea anisotropic elastic properties in vivo. TRANSLATIONAL RELEVANCE As OCT is broadly accepted in Ophthalmology, these results suggest the potential for rapid translation of AuT-OCE into clinical practice. In addition, AuT-OCE can likely improve diagnostic criteria of ectatic corneal diseases, leading to early diagnosis, reduced complications, customized surgical treatment, and personalized biomechanical models of the eye.
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Affiliation(s)
- Mitchell A. Kirby
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
| | - Gabriel Regnault
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
- Correspondence: Gabriel Regnault, Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
| | - Ivan Pelivanov
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
| | - Matthew O’Donnell
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
| | - Ruikang K. Wang
- Department of Bioengineering, University of Washington, Seattle, Washington 98105, USA
- Department of Ophthalmology, University of Washington, Seattle, Washington 98104, USA
| | - Tueng T. Shen
- School of Medicine, University of Washington, Seattle, Washington 98195, USA
- Department of Ophthalmology, University of Washington, Seattle, Washington 98104, USA
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Liu JTC, Bale G, Choe R, Elson DS, Oldenburg A, Tian L, Tkaczyk ER. Introduction to the Biophotonics Congress 2022 feature issue. BIOMEDICAL OPTICS EXPRESS 2023; 14:385-386. [PMID: 36698666 PMCID: PMC9842003 DOI: 10.1364/boe.483553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2022] [Indexed: 06/17/2023]
Abstract
A feature issue is being presented by a team of guest editors containing papers based on studies presented at the Optica Biophotonics Congress: Biomedical Optics held on April 24-27, 2022 in Fort Lauderdale, Florida, USA.
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Affiliation(s)
- Jonathan T. C. Liu
- Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
- Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98195, USA
| | - Gemma Bale
- Department of Engineering, University of Cambridge, CB3 0FA, UK
- Department of Physics, University of Cambridge, CB3 0HE, UK
| | - Regine Choe
- Department of Biomedical Engineering, University of Rochester, Rochester, NY 14627, USA
| | - Daniel S. Elson
- Hamlyn Centre for Robotic Surgery, Department of Surgery and Cancer, Imperial College London, London SW7 2AZ, UK
| | - Amy Oldenburg
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Lin Tian
- Department of Biochemistry and Molecular Medicine, University of California, Davis, Davis, 95616, USA
| | - Eric R. Tkaczyk
- Dermatology and Research Services, Department of Veterans Affairs, Nashville, TN 37212, USA
- Department of Dermatology, Vanderbilt University Medical Center, Nashville, TN 37204, USA
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37212, USA
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Acoustic Micro-Tapping Optical Coherence Elastography to Quantify Corneal Collagen Cross-Linking: An Ex Vivo Human Study. OPHTHALMOLOGY SCIENCE 2022; 3:100257. [PMID: 36685713 PMCID: PMC9852959 DOI: 10.1016/j.xops.2022.100257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/25/2022] [Accepted: 11/08/2022] [Indexed: 11/15/2022]
Abstract
Purpose To evaluate changes in the anisotropic elastic properties of ex vivo human cornea treated with ultraviolet cross-linking (CXL) using noncontact acoustic micro-tapping optical coherence elastography (AμT-OCE). Design Acoustic micro-tapping OCE was performed on normal and CXL human donor cornea in an ex vivo laboratory study. Subjects Normal human donor cornea (n = 22) divided into 4 subgroups. All samples were stored in optisol. Methods Elastic properties (in-plane Young's, E, and out-of-plane, G, shear modulus) of normal and ultraviolet CXL-treated human corneas were quantified using noncontact AμT-OCE. A nearly incompressible transverse isotropic model was used to reconstruct moduli from AμT-OCE data. Independently, cornea elastic moduli were also measured with destructive mechanical tests (tensile extensometry and shear rheometry). Main Outcome Measures Corneal elastic moduli (in-plane Young's modulus, E, in-plane, μ, and out-of-plane, G, shear moduli) can be evaluated in both normal and CXL treated tissues, as well as monitored during the CXL procedure using noncontact AμT-OCE. Results Cross-linking induced a significant increase in both in-plane and out-of-plane elastic moduli in human cornea. The statistical mean in the paired study (presurgery and postsurgery, n = 7) of the in-plane Young's modulus, E = 3 μ , increased from 19 MPa to 43 MPa, while the out-of-plane shear modulus, G, increased from 188 kPa to 673 kPa. Mechanical tests in a separate subgroup support CXL-induced cornea moduli changes and generally agree with noncontact AμT-OCE measurements. Conclusions The human cornea is a highly anisotropic material where in-plane mechanical properties are very different from those out-of-plane. Noncontact AμT-OCE can measure changes in the anisotropic elastic properties in human cornea as a result of ultraviolet CXL.
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