In vivo measurement of shear modulus of the human cornea using optical coherence elastography

Ramier, Antoine; Eltony, Amira M.; Chen, Yitong; Clouser, Fatima; Birkenfeld, Judith; Watts, Amy; Yun, Seok Hyun

doi:10.1038/s41598-020-74383-4

Cited by 79 publications

(72 citation statements)

References 37 publications

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“…These observations led us to propose that our eye phantoms could be utilized to investigate deformation of the eye caused by IOP change or to measure the tension from the outside of the eyeball. Indeed, a recent study on biomechanics of an in vivo human cornea showed that the corneal shear modulus was independent of both CCT as well as IOP 17 .…”

Section: Discussionmentioning

confidence: 99%

Development of Eye Phantoms for Mimicking the Structural Deformation of the Human Cornea Accompanied With Intraocular Pressure Alteration

Cho

Jeoung

2021

Preprint

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We developed a fully continuous eye phantom to better understand structural deformation of the cornea under varying intraocular pressure (IOP). The IOP-induced deformation and tension of the eye phantom were investigated using optical coherence tomography and non-contact tonometer readings, respectively. A fixed-cornea eye phantom, which featured a soft cornea, was also used for comparison. We evaluated the corneal structural changes between the two different types of eye phantoms by estimating the central corneal thickness (CCT) and corneal radius of curvature (CRC). For the eye phantom with an initial CCT of 0.55 mm, which is close to the average human CCT, CRC of the fully continuous eye phantoms showed a positive correlation to true IOP, while the CRC of a fixed-cornea eye phantom had a negative correlation. Non-contact tonometry readings for fixed-cornea eye phantoms were higher than those of full-eye phantoms due to the structural and mechanical characteristics. Considering the results from in vitro studies on enucleated human eyeballs, a fully continuous eye phantom is a more suitable choice for mimicking human IOP than a fixed-cornea eye phantom. Use of a more reliable eye phantom for accurate estimation of IOP using tonometry may eventually improve the accuracy of glaucoma screening.

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Section: Discussionmentioning

confidence: 99%

Development of Eye Phantoms for Mimicking the Structural Deformation of the Human Cornea Accompanied With Intraocular Pressure Alteration

Cho

Jeoung

2021

Preprint

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“…OCE (compression, ARF based, and shear wave.) is extensively used to assess the viscoelastic properties of the human cornea in vivo as the superior submicron scale resolution of OCT can capture subtle changes in wave properties [153] and tissue properties, making it suitable for the detection of early-onset disease such as keratoconus [154]. In addition, in vivo dynamic OCE has been performed on human skin to assess its mechanical properties [155].…”

Section: Adult Tissuementioning

confidence: 99%

Existing and Potential Applications of Elastography for Measuring the Viscoelasticity of Biological Tissues In Vivo

et al. 2021

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Mechanical tissue properties contribute to tissue shape change during development. Emerging evidence suggests that gradients of viscoelasticity correspond to cell movement and gene expression patterns. To accurately define mechanisms of morphogenesis, a combination of precise empirical measurements and theoretical approaches are required. Here, we review elastography as a method to characterize viscoelastic properties of tissue in vivo. We discuss its current clinical applications in mature tissues and its potential for characterizing embryonic tissues.

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“…Optical coherence elastography (OCE) was developed by combining a loading system to exert a sample stimulation force and an optical coherence tomography (OCT) system to observe the resulting tissue displacements (strains) or mechanical waves ( Schmitt, 1998 ). OCT/OCE provides micrometer-scale axial and lateral resolutions, and the use of phase-sensitive OCT detection ( Zhao et al, 2000 ; Kirkpatrick et al, 2006 ) can further enhance the dynamic elastography detection sensitivity to a sub-nanometer scale ( Lan et al, 2017 ), making it possible to detect minute-magnitude dynamics for in vivo human corneas ( Lan et al, 2020a ; Ramier et al, 2020 ; Lan et al, 2021b ). The measurement of tissue biomechanics typically centers on Young’s modulus, a representation of elasticity expressed as the slope between the force (stress) and the resulting fractional deformation (strain).…”

Section: Introductionmentioning

confidence: 99%

Spatial Assessment of Heterogeneous Tissue Natural Frequency Using Micro-Force Optical Coherence Elastography

Lan

Shi

Wang

et al. 2022

Front. Bioeng. Biotechnol.

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Analysis of corneal tissue natural frequency was recently proposed as a biomarker for corneal biomechanics and has been performed using high-resolution optical coherence tomography (OCT)-based elastography (OCE). However, it remains unknown whether natural frequency analysis can resolve local variations in tissue structure. We measured heterogeneous samples to evaluate the correspondence between natural frequency distributions and regional structural variations. Sub-micrometer sample oscillations were induced point-wise by microliter air pulses (60–85 Pa, 3 ms) and detected correspondingly at each point using a 1,300 nm spectral domain common path OCT system with 0.44 nm phase detection sensitivity. The resulting oscillation frequency features were analyzed via fast Fourier transform and natural frequency was characterized using a single degree of freedom (SDOF) model. Oscillation features at each measurement point showed a complex frequency response with multiple frequency components that corresponded with global structural features; while the variation of frequency magnitude at each location reflected the local sample features. Silicone blocks (255.1 ± 11.0 Hz and 249.0 ± 4.6 Hz) embedded in an agar base (355.6 ± 0.8 Hz and 361.3 ± 5.5 Hz) were clearly distinguishable by natural frequency. In a beef shank sample, central fat and connective tissues had lower natural frequencies (91.7 ± 58.2 Hz) than muscle tissue (left side: 252.6 ± 52.3 Hz; right side: 161.5 ± 35.8 Hz). As a first step, we have shown the possibility of natural frequency OCE methods to characterize global and local features of heterogeneous samples. This method can provide additional information on corneal properties, complementary to current clinical biomechanical assessments, and could become a useful tool for clinical detection of ocular disease and evaluation of medical or surgical treatment outcomes.

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In vivo measurement of shear modulus of the human cornea using optical coherence elastography

Cited by 79 publications

References 37 publications

Development of Eye Phantoms for Mimicking the Structural Deformation of the Human Cornea Accompanied With Intraocular Pressure Alteration

Development of Eye Phantoms for Mimicking the Structural Deformation of the Human Cornea Accompanied With Intraocular Pressure Alteration

Existing and Potential Applications of Elastography for Measuring the Viscoelasticity of Biological Tissues In Vivo

Spatial Assessment of Heterogeneous Tissue Natural Frequency Using Micro-Force Optical Coherence Elastography

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