Determinants of Human Corneal Mechanical Wave Dispersion for In Vivo Optical Coherence Elastography

Translational Vision Science & Technology, Journal Year: 2025, Volume and Issue: 14(1), P. 26 - 26

Published: Jan. 24, 2025

Purpose: To characterize frequency-dependent wave speed dispersion in the human cornea using microliter air-pulse optical coherence elastography (OCE), and to evaluate applicability of Lamb theory for determining corneal elastic modulus high-frequency symmetric (S0) anti-symmetric (A0) guided waves cornea. Methods: Wave analysis transient (0.5 ms) stimulation was performed four rabbit eyes ex vivo compared air-coupled ultrasound excitation. The effects angle sample geometry on were evaluated phantoms. Corneal measured 36 healthy vivo. Results: Air-pulse-induced comparable ultrasound-induced between 0.7 5 kHz (mean-difference ± 1.96 × SD: 0.006 0.5 m/s) corneas. Stimulation 0° relative surface normal generated A0 tissue phantoms, while oblique (35° 65°) S0 waves. Stimulating apex (0°) induced waves, plateauing at 10.87 13.63 m/s 4 kHz, when obliquely stimulated periphery (65°), produced 13.10 15.98 kHz. Conclusions: Air-pulse OCE can be used measure propagation modes These are selectively excited by changing angle. Accounting enables reliable estimation Translational Relevance: This work demonstrates feasibility robust measurements stiffness disease detection therapy evaluation.

Language: Английский

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Corneal biomechanics and diagnostics: a review

International Ophthalmology, Journal Year: 2024, Volume and Issue: 44(1)

Published: March 13, 2024

Abstract Purpose Corneal biomechanics is an emerging field and the interest into physical biological interrelations in anterior part of eye has significantly increased during past years. There are many factors that determine corneal such as hormonal fluctuations, hydration environmental factors. Other can affect corneas age, intraocular pressure central thickness. The purpose this review to evaluate affecting recent advancements non-destructive, vivo measurement techniques for early detection improved management diseases. Methods Until recently, could not be directly assessed humans were instead inferred from geometrical cornea analysis ex biomechanical testing. current research made strides studying creating non-destructive contactless measure properties vivo. Results Research indicated altered contribute diseases keratoconus glaucoma. identification pathological through new imperative preventing postoperative complications. Conclusions Identification crucial prevention Therefore, a better understanding will lead earlier diagnosis ectatic disorders, improve refractive surgeries allow treatment.

Language: Английский

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Multi-modal imaging for the detection of early keratoconus: a narrative review

Eye and Vision, Journal Year: 2024, Volume and Issue: 11(1)

Published: May 11, 2024

Abstract Keratoconus is a common progressive corneal disorder that can be associated with significant ocular morbidity. Various imaging techniques have been used for the diagnosis of established cases. However, in early stages disease, which include subclinical keratoconus and forme fruste keratoconus, detection such cases challenging. The importance detecting very important because intervention halt disease progression, improve visual outcomes prevent postrefractive surgery ectasia performing refractive procedures patients. This narrative review aimed to examine several evolving keratoconus. utilization combinations these may further increase their diagnostic ability.

Language: Английский

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Assessing UVA and Laser‐Induced Crosslinking via Brillouin Microscopy

Journal of Biophotonics, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 16, 2025

ABSTRACT Keratoconus and other corneal ectatic disorders involve the degradation of collagen fibers, which compromises biomechanical properties. Ultraviolet‐A (UVA) crosslinking has emerged as primary treatment to slow down degradation. This is limited in both penetration depth spatial precision, potentially leading unwanted side effects. study compares changes properties corneas crosslinked with UVA irradiation a near‐infrared femtosecond laser, using Brillouin microscopy. The regions were mapped terms frequency shift three dimensions. showed an average increase ~100 MHz. We demonstrate targeted axial crosslinking, similar values regions.

Language: Английский

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Air-pulse optical coherence elastography: how excitation angle affects mechanical wave propagation

Biomedical Optics Express, Journal Year: 2025, Volume and Issue: 16(4), P. 1371 - 1371

Published: March 4, 2025

We evaluate the effect of excitation angles on observation and characterization surface wave propagations used to derive tissue’s mechanical properties in optical coherence tomography (OCT)-based elastography (OCE). Air-pulse stimulation was performed at center sample with ranging from oblique (e.g., 70° or 45°) perpendicular (0°). OCT scanning conducted radially record en face 360°, features (amplitude, attenuation, group phase velocities) were calculated spatiotemporal wavenumber-frequency domains. measurements isotropic, homogeneous samples (1–1.6% agar phantoms), anisotropic (chicken breast), complex boundaries, coupling media, stress conditions ( ex vivo porcine cornea, intraocular pressure (IOP): 5–20 mmHg). Our findings indicate that velocities are less affected by compared displacement features, demonstrating robustness using waves for elasticity estimations. Agar chicken breast showed all these metrics (particularly relatively consistent when smaller than 45°. However, significant disparities observed cornea across different (even between 15° 0°), particularly high IOP levels 20 provide valuable insights enhancing accuracy biomechanical assessments air-pulse-based other dynamic OCE approaches. This facilitates refinement clinical translation technique could ultimately improve diagnostic therapeutic applications various biomedical fields.

Language: Английский

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Shear Wave Optical Coherence Elastography Imaging by Deep Learning

Journal of Biophotonics, Journal Year: 2025, Volume and Issue: unknown

Published: April 10, 2025

ABSTRACT Quantifying ocular tissue mechanical properties is pivotal for elucidating eye disease etiology and progression. Optical coherence elastography (OCE), leveraging high‐resolution optical tomography, promises stiffness assessment. Traditional OCE relies on data processing of the time‐of‐flight method encounters challenges like low repeatability. Our study presents an optimized workflow integrating with deep learning to predict biomechanical properties. The concentration prediction network (CPN), a 3D convolutional neural network, predicts sample's concentrations calculates Young's modulus based relationship between agar from testing. CPN showed high accuracy, mean absolute error 0.028 ± 0.036 training 0.024 testing phantoms. In situ porcine corneas various intraocular pressures was measured, yielding corneal distribution via method. This approach enhances efficiency underscores potential clinical applications in ophthalmology.

Language: Английский

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Research Progress on Measurement Methods and Clinical Applications of Corneal Elastic Modulus

Experimental Eye Research, Journal Year: 2024, Volume and Issue: 245, P. 109974 - 109974

Published: June 17, 2024

Language: Английский

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Spatial mapping of corneal biomechanical properties using wave‐based optical coherence elastography

Journal of Biophotonics, Journal Year: 2024, Volume and Issue: 17(6)

Published: March 7, 2024

Abstract Quantifying the mechanical properties of cornea can provide valuable insights into occurrence and progression keratoconus, as well effectiveness corneal crosslinking surgery. This study presents a non‐contact non‐invasive wave‐based optical coherence elastography system that utilizes air‐pulse stimulation to create two‐dimensional map elasticity. Homogeneous dual concentration phantoms were measured with sampling 25 × points over 6.6 mm 2 area, verify measurement capability for elastic mapping spatial resolution (0.91 mm). The velocity waves distribution porcine corneas before after surgery further mapped, showing significant change in biomechanics crosslinked region. features non‐invasiveness high resolution, holding great potential application ophthalmic clinics.

Language: Английский

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A Comprehensive Study on Elasticity and Viscosity on Biomechanics and Optical Properties of the Living Human Cornea

Published: May 2, 2024

Corneal biomechanics is a hot topic in ophthalmology. The biomechanical properties of the cornea (BMPs) have important implications management and diagnosis corneal diseases such as ectasia keratoconus. In addition, characterization BMPs crucial to model predictability surgery intervention, outcomes refractive or follow-up diseases. behavior governed by viscoelastic that allow, among other structural implications, damping excess intraocular pressure reduce damage optic nerve. Currently, most versatile complete methods measure viscoelasticity are based on air-puff applanation. However, those lack ability directly viscosity. aim this work propose new methodology analysis measurements through Standard Linear Solid (SLSM) provide analytical expressions separately calculate elastic time-dependent (corneal retardation time viscosity) properties. results shown mean values elasticity (E), viscosity (Ƞ) (τ) sample 200 young healthy subjects. influence viscoelasticity, high-order aberrations optical transparency investigated. Finally, SLSM fed back from experimental E Ƞ was employed compare creep-relaxation response between normal, an ocular hypertension patient Ortho-K user.

Language: Английский

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The Utilization of Brillouin Microscopy in Corneal Diagnostics: A Systematic Review

Cureus, Journal Year: 2024, Volume and Issue: unknown

Published: July 30, 2024

Corneal biomechanical data has been used since 2005 to screen for keratoconus and corneal ectasia by specialists. Older technology uses force applanation techniques over a 3 mm area in the central cornea, making it highly dependent on extraneous variables unable calculate elasticity of tissue. Brillouin microscopy is newer method that natural shift frequency light as passes through material. This can be estimate viscoelasticity The advantage create full three-dimensional (3D) map entire cornea without direct contact. A literature search was conducted using databases PubMed, Google Scholar, Ovid regarding applications diagnostics. final total 16 articles included describing various ex vivo studies microscopy. Applications this spanned from diagnosis post-corneal refractive surgery evaluation. All evaluated biomechanics other properties quantification shifts. Many found diagnostic device capable detecting subtle changes thickness keratoconic corneas at high level specificity sensitivity. However, limitations may include duration time required use fluctuations accuracy depending hydration state. Future seems geared toward combination optical coherence tomography (OCT) microscopy, OCT pupil-tracking modality. Further research understanding involved will lead better care patients field ophthalmology.

Language: Английский

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