1. Articles from Sabine Kling

    1-6 of 6
    1. Motion Estimation for Optical Coherence Elastography Using Signal Phase and Intensity

      Motion Estimation for Optical Coherence Elastography Using Signal Phase and Intensity

      Abstract —Displacement estimation in optical coherence tomog- raphy (OCT) imaging is relevant for several potential applica- tions, e.g. for optical coherence elastography (OCE) for corneal biomechanical characterization. Larger displacements may be resolved using correlation-based block matching techniques, which however are prone to signal de-correlation and imprecise at commonly desired sub-pixel resolutions. Phase-based tracking methods can estimate tiny sub-wavelength motion, but are not suitable for motion magnitudes larger than half the wavelength due to phase wrapping and the difficulty of any unwrapping due to noise. In this paper a robust OCT displacement estimation method is introduced by formulating tracking as ...

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    2. Quasi-Static Optical Coherence Elastography to Characterize Human Corneal Biomechanical Properties

      Quasi-Static Optical Coherence Elastography to Characterize Human Corneal Biomechanical Properties

      Purpose : Quasi-static optical coherence elastography (OCE) is an emerging technology to investigate corneal biomechanical behavior in situations similar to physiological stress conditions. Herein OCE was applied to evaluate previously inaccessible biomechanical characteristics of human corneal tissue and to study the role of Bowman's layer in corneal biomechanics. Methods : Human corneal donor buttons ( n = 23) were obtained and Descemet's membrane and endothelium were removed. In 11 corneas, Bowman's layer was ablated by a 20 µm stromal excimer laser ablation. Buttons were mounted on an artificial anterior chamber and subjected to a pressure modulation from 10 to 30 mm ...

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    3. Optical coherence elastography by ambient pressure modulation for high-resolution strain mapping applied to patterned cross-linking

      Optical coherence elastography by ambient pressure modulation for high-resolution strain mapping applied to patterned cross-linking

      The purpose of this study was to develop a novel non-contact optical coherence elastography (OCE) approach to measure laterally and axially highly resolved corneal strain distribution at different stages of patterned corneal cross-linking (CXL). Freshly enucleated rat eyes were obtained and prepared for accelerated patterned CXL treatment with distinct ultraviolet (UV) patterns (central, peripheral, bow-tie irradiation). Each cornea was measured repeatedly, in three different conditions: (i) virgin, (ii) after epithelial debridement and 0.5% hypo-osmolar riboflavin instillation for 30 min, and (iii) after patterned CXL at 9 mW cm −2 for 10 min. For biomechanical assessment, the corneal deformation response ...

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    4. Observation of sound-induced corneal vibrational modes by optical coherence tomography

      Observation of sound-induced corneal vibrational modes by optical coherence tomography

      The mechanical stability of the cornea is critical for maintaining its normal shape and refractive function. Here, we report an observation of the mechanical resonance modes of the cornea excited by sound waves and detected by using phase-sensitive optical coherence tomography. The cornea in bovine eye globes exhibited three resonance modes in a frequency range of 50-400 Hz. The vibration amplitude of the fundamental mode at 80-120 Hz was ~8 µm at a sound pressure level of 100 dB (2 Pa). Vibrography allows the visualization of the radially symmetric profiles of the resonance modes. A dynamic finite-element analysis supports our ...

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    5. Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties

      Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties

      Most techniques measuring corneal biomechanics in vivo are biased by side factors. We demonstrate the ability of optical coherence tomographic (OCT) vibrography to determine corneal material parameters, while reducing current prevalent restrictions of other techniques (such as intraocular pressure (IOP) and thickness dependency). Modal analysis was performed in a finite-element (FE) model to study the oscillation response in isolated thin corneal flaps/eye globes and to analyse the dependency of the frequency response function on: corneal elasticity, viscoelasticity, geometry (thickness and curvature), IOP and density. The model was verified experimentally in flaps from three bovine corneas and in two enucleated ...

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    6. Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas

      Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas

      A new technique is presented for the non-invasive imaging of the dynamic response of the cornea to an air puff inducing a deformation. A spectral OCT instrument combined with an air tonometer in a non-collinear configuration was used to image the corneal deformation over full corneal cross-sections, as well as to obtain high speed measurements of the temporal evolution of the corneal apex. The entire deformation process can be dynamically visualized. A quantitative analysis allows direct extraction of several deformation parameters, such as amplitude, diameter and volume of the maximum deformation, as well as duration and speed of the increasing ...

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    1-6 of 6
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    1. (3 articles) Spanish National Research Council
    2. (2 articles) Harvard University
    3. (2 articles) Massachusetts General Hospital
    4. (1 articles) University of Maryland
    5. (1 articles) University of Zurich
    6. (1 articles) University of Geneva
    7. (1 articles) National Institutes of Health
    8. (1 articles) Tokyo Medical & Dental University
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    Dynamic OCT measurement of corneal deformation by an air puff in normal and cross-linked corneas Numerical model of optical coherence tomographic vibrography imaging to estimate corneal biomechanical properties Observation of sound-induced corneal vibrational modes by optical coherence tomography Optical coherence elastography by ambient pressure modulation for high-resolution strain mapping applied to patterned cross-linking Quasi-Static Optical Coherence Elastography to Characterize Human Corneal Biomechanical Properties Motion Estimation for Optical Coherence Elastography Using Signal Phase and Intensity The Structural and Comparative Analysis of Intravitreal Dexamethasone Implant (Ozurdex) and Anti-VEGF Injection in Branched Retinal Vein Occlusion Patients by Optical Coherence Tomography Angiography Images Quantitation Vascular Responses to First-Generation Sirolimus-Eluting Stents and Bare-Metal Stents Beyond 10 Years Ocular Parameters Evaluation in Relation to the Refractive Error using Optical Coherence Topography Micro Optical Coherence Tomography for Coronary Imaging Macular Vessel Density in Diabetic Retinopathy Patients: How Can We Accurately Measure and What Can It Tell Us? Systems and methods for long working distance optical coherence tomography (OCT)