1. Articles from Joseph A. Izatt

    1-24 of 203 1 2 3 4 5 6 7 8 9 »
    1. Video-rate high-precision time-frequency multiplexed 3D coherent ranging

      Video-rate high-precision time-frequency multiplexed 3D coherent ranging

      Frequency-modulated continuous wave (FMCW) light detection and ranging (LiDAR) is an emerging 3D ranging technology that offers high sensitivity and ranging precision. Due to the limited bandwidth of digitizers and the speed limitations of beam steering using mechanical scanners, meter-scale FMCW LiDAR systems typically suffer from a low 3D frame rate, which greatly restricts their applications in real-time imaging of dynamic scenes. In this work, we report a high-speed FMCW based 3D imaging system, combining a grating for beam steering with a compressed time-frequency analysis approach for depth retrieval. We thoroughly investigate the localization accuracy and precision of our system ...

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      Mentions: Thorlabs
    2. Macular Neurovascular Abnormalities in a Child with Incontinentia Pigmenti on Handheld Optical Coherence Tomography Angiography

      Macular Neurovascular Abnormalities in a Child with Incontinentia Pigmenti on Handheld Optical Coherence Tomography Angiography

      Purpose: To report macular neurovascular abnormalities in a child with incontinentia pigmenti using handheld optical coherence tomography (OCT) and OCT angiography (OCT-A). Methods: An eye of a child with incontinentia pigmenti enrolled in BabySTEPS was imaged using an investigational noncontact, handheld swept-source OCT device during examination under anesthesia. Custom MATLAB scripts were used to generate depth-resolved vascular slabs, B-scans with flow overlay, and retinal thickness maps. Results: Depth-resolved OCT and OCT-A imaging demonstrated focal areas of decreased capillary flow that corresponded to areas of both inner retinal and outer retinal thinning on retinal thickness maps. Atypical diving of superficial retinal ...

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      Mentions: Duke University
    3. Computational 3D microscopy with optical coherence refraction tomography

      Computational 3D microscopy with optical coherence refraction tomography

      Optical coherence tomography (OCT) has seen widespread success as an in vivo clinical diagnostic 3D imaging modality, impacting areas including ophthalmology, cardiology, and gastroenterology. Despite its many advantages, such as high sensitivity, speed, and depth penetration, OCT suffers from several shortcomings that ultimately limit its utility as a 3D microscopy tool, such as its pervasive coherent speckle noise and poor lateral resolution required to maintain millimeter-scale imaging depths. Here, we present 3D optical coherence refraction tomography (OCRT), a computational extension of OCT that synthesizes an incoherent contrast mechanism by combining multiple OCT volumes, acquired across two rotation axes, to form ...

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    4. Robotically aligned optical coherence tomography with 5 degree of freedom eye tracking for subject motion and gaze compensation

      Robotically aligned optical coherence tomography with 5 degree of freedom eye tracking for subject motion and gaze compensation

      Optical coherence tomography (OCT) has revolutionized diagnostics in ophthalmology. However, OCT requires a trained operator and patient cooperation to carefully align a scanner with the subject’s eye and orient it in such a way that it images a desired region of interest at the retina. With the goal of automating this process of orienting and aligning the scanner, we developed a robot-mounted OCT scanner that automatically aligned with the pupil while matching its optical axis with the target region of interest at the retina. The system used two 3D cameras for face tracking and three high-resolution 2D cameras for ...

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      Mentions: Duke University
    5. Depth-Resolved Visualization of Perifoveal Retinal Vasculature in Preterm Infants Using Handheld Optical Coherence Tomography Angiography

      Depth-Resolved Visualization of Perifoveal Retinal Vasculature in Preterm Infants Using Handheld Optical Coherence Tomography Angiography

      Purpose: To establish methods to visualize depth-resolved perifoveal retinal vasculature in preterm infants using handheld optical coherence tomography angiography (OCT-A). Methods: In this exploratory study, eyes of preterm infants were imaged using an investigational noncontact, handheld swept-source OCT-A device as part of the prospective BabySTEPS infant retinal imaging study. We selected high-quality OCT-A volumes at two developmental stages for analysis. Customized MATLAB scripts were used to segment retinal layers, test offset parameters, and generate depth-resolved OCT-A slabs. The superficial (SCP), intermediate (ICP), and deep (DCP) capillary plexuses were visualized and qualitatively assessed by three image graders. Results: Six eyes from ...

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      Mentions: Duke University
    6. Contactless optical coherence tomography of the eyes of freestanding individuals with a robotic scanner

      Contactless optical coherence tomography of the eyes of freestanding individuals with a robotic scanner

      Clinical systems for optical coherence tomography (OCT) are used routinely to diagnose and monitor patients with a range of ocular diseases. They are large tabletop instruments operated by trained staff, and require mechanical stabilization of the head of the patient for positioning and motion reduction. Here we report the development and performance of a robot-mounted OCT scanner for the autonomous contactless imaging, at safe distances, of the eyes of freestanding individuals without the need for operator intervention or head stabilization. The scanner uses robotic positioning to align itself with the eye to be imaged, as well as optical active scanning ...

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      Mentions: Duke University
    7. Unified k-space theory of optical coherence tomography

      Unified k-space theory of optical coherence tomography

      We present a general theory of optical coherence tomography (OCT), which synthesizes the fundamental concepts and implementations of OCT under a common 3D k -space framework. At the heart of this analysis is the Fourier diffraction theorem, which relates the coherent interaction between a sample and plane wave to the Ewald sphere in the 3D k space representation of the sample. While only the axial dimension of OCT is typically analyzed in k -space, we show that embracing a fully 3D k space formalism allows explanation of nearly every fundamental physical phenomenon or property of OCT, including contrast mechanism, resolution ...

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      Mentions: Duke University
    8. Microscope-Integrated OCT-Guided Volumetric Measurements of Subretinal Blebs Created by a Suprachoroidal Approach

      Microscope-Integrated OCT-Guided Volumetric Measurements of Subretinal Blebs Created by a Suprachoroidal Approach

      Purpose: To investigate the use of imaging modalities in the volumetric measurement of the subretinal space and examine the volume of subretinal blebs created by a subretinal drug delivery device utilizing microscope-integrated optical coherence tomography (MIOCT). Methods: An MIOCT image-based volume measurement method was developed and assessed for accuracy and reproducibility by imaging ceramic spheres of known size that were surgically implanted into ex vivo porcine eyes. This method was then used to measure subretinal blebs created in 10 porcine eyes by injection of balanced salt solution utilizing a subretinal delivery device via a suprachoroidal cannula. Bleb volumes obtained from ...

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      Mentions: Duke University
    9. Systems and methods for long working distance optical coherence tomography (OCT)

      Systems and methods for long working distance optical coherence tomography (OCT)

      Systems and methods for long working distance optical coherence tomography (OCT). According to an aspect, an OCT system includes a reference arm. Further, the OCT system includes a sample arm operably connected to the reference arm. The sample arm includes a scanner configured to scan an optical beam. The sample arm also includes an objective positioned a predetermined distance from the scanner, configured to receive the optical beam, and to direct the optical beam to an object positioned at about the predetermined distance from the scanner for imaging of the object.

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      Mentions: Duke University
    10. In Vivo Quantitative Analysis of Anterior Chamber White Blood Cell Mixture Composition Using Spectroscopic Optical Coherence Tomography

      In Vivo Quantitative Analysis of Anterior Chamber White Blood Cell Mixture Composition Using Spectroscopic Optical Coherence Tomography

      Anterior uveitis is the most common form of intraocular inflammation, and one of its main signs is the presence of white blood cells (WBCs) in the anterior chamber (AC). Clinically, the true composition of cells can currently only be obtained using AC paracentesis, an invasive procedure to obtain AC fluid requiring needle insertion into the AC. We previously developed a spectroscopic optical coherence tomography (SOCT) analysis method to differentiate between populations of RBCs and subtypes of WBCs, including granulocytes, lymphocytes and monocytes, both in vitro and in ACs of excised porcine eyes. We have shown that different types of WBCs ...

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      Mentions: Duke University
    11. Macular Optical Coherence Tomography Characteristics at 36 weeks Postmenstrual Age in Infants Examined for Retinopathy of Prematurity

      Macular Optical Coherence Tomography Characteristics at 36 weeks Postmenstrual Age in Infants Examined for Retinopathy of Prematurity

      Objective To report our ability to capture, grade reliably and analyze bedside macular optical coherence tomography (OCT) images from preterm infants and relate OCT findings to biological factors and retinopathy of prematurity (ROP) status at a single time window in the STudy of Eye imaging in Preterm infantS (BabySTEPS). Design Prospective observational study Participants Preterm infants eligible for ROP screening, with parental consent for research and a 36±1 weeks postmenstrual age (PMA) visit. Methods We imaged both eyes of preterm infants with an investigational non-contact, handheld swept-source OCT at the time of clinical ROP examinations. Macular OCT features and ...

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    12. Auto-Processed Retinal Vessel Shadow View Images From Bedside Optical Coherence Tomography to Evaluate Plus Disease in Retinopathy of Prematurity

      Auto-Processed Retinal Vessel Shadow View Images From Bedside Optical Coherence Tomography to Evaluate Plus Disease in Retinopathy of Prematurity

      Abstract Purpose : To describe the creation of en face retinal vessel shadow view (RVSV) optical coherence tomography (OCT) images and assess the feasibility of using these for evaluating vascular disease in preterm infants at risk for retinopathy of prematurity (ROP). Methods : In this exploratory study, we selected images from eyes with a range of ROP vascular disease, prospectively acquired from preterm infants using an investigational, noncontact, handheld, bedside swept-source OCT. We autosegmented OCT volumes using custom infant-specific software, extracted RVSV-OCT images from volumetric data bracketed around the retinal pigment epithelium, and automontaged the resulting RVSV-OCT images. Three masked ophthalmologists graded ...

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      Mentions: Duke University
    13. Lightweight Learning-based Automatic Segmentation of Subretinal Blebs on Microscope-Integrated Optical Coherence Tomography Images

      Lightweight Learning-based Automatic Segmentation of Subretinal Blebs on Microscope-Integrated Optical Coherence Tomography Images

      Purpose Subretinal injections of therapeutics are commonly used to treat ocular diseases. Accurate dosing of therapeutics at target locations is crucial but difficult to achieve using subretinal injections due to leakage, and there is no method available to measure the volume of therapeutics successfully administered to the subretinal location during surgery. Here we introduce the first automatic method for quantifying the volume of subretinal blebs, using porcine eyes injected with Ringer’s lactate solution as samples. Design Experimental study. Methods Microscope-integrated optical coherence tomography was utilized to obtain 3D visualization of subretinal blebs in porcine eyes at Duke Eye Center ...

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    14. Quantitative topographic curvature maps of the posterior eye utilizing optical coherence tomography

      Quantitative topographic curvature maps of the posterior eye utilizing optical coherence tomography

      Purpose: Deformations of the retina such as staphylomas in myopia or scleral flattening in high intracranial pressure can be challenging to quantify with en face imaging. We describe an OCT based method for the generation of quantitative posterior eye topography maps in normal and pathologic eyes. Methods: Utilizing “ whole eye ” OCT we corrected for subjects’ optical distortions to generate spatially accurate posterior eye OCT volumes and created local curvature ( K M , mm -1 ) topography maps for each consented subject. We imaged nine subjects, three normal, two with myopic degeneration (MD), and four with papilledema including one that was imaged longitudinally ...

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      Mentions: Duke University
    15. Systems and methods for eye tracking for motion corrected ophthalmic optical coherence tomography

      Systems and methods for eye tracking for motion corrected ophthalmic optical coherence tomography

      Systems and methods for eye tracking for motion corrected ophthalmic optical coherence tomography (OCT) are disclosed. According to an aspect, an imaging system includes an eye tracking device configured to determine movement of an eye. The imaging system also includes an OCT apparatus configured to generate OCT images of a retina of the eye. The OCT apparatus includes a scanner operable to be moved for relocating an OCT scan pivot at a pupil plane for image capture and during capture of the OCT images. The imaging system also includes a controller configured to control the scanner to relocate the OCT ...

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      Mentions: Duke University
    16. Spectroscopic optical coherence refraction tomography

      Spectroscopic optical coherence refraction tomography

      In optical coherence tomography (OCT), the axial resolution is often superior to the lateral resolution, which is sacrificed for long imaging depths. To address this anisotropy, we previously developed optical coherence refraction tomography (OCRT), which uses images from multiple angles to computationally reconstruct an image with isotropic resolution, given by the OCT axial resolution. On the other hand, spectroscopic OCT (SOCT), an extension of OCT, trades axial resolution for spectral resolution and hence often has superior lateral resolution. Here, we present spectroscopic OCRT (SOCRT), which uses SOCT images from multiple angles to reconstruct a spectroscopic image with isotropic spatial resolution ...

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      Mentions: Duke University
    17. Optical Coherence Tomography Guided Robotic Needle Insertion for Deep Anterior Lamellar Keratoplasty

      Optical Coherence Tomography Guided Robotic Needle Insertion for Deep Anterior Lamellar Keratoplasty

      Objective: Deep anterior lamellar keratoplasty (DALK) significantly reduces the post-transplantation morbidity in patients eligible for partial-thickness cornea grafts. The popular "big bubble" technique for DALK is so challenging, however, that a significant fraction of corneal pneumodissection attempts fail for surgeons without extensive DALK-specific experience, even with previous-generation cross-sectional optical coherence tomography (OCT) guidance. We seek to develop robotic, volumetric OCT-guided technology capable of facilitating or automating the difficult needle insertion step in DALK. Methods: Our system provides for real-time volumetric corneal imaging, segmentation, and tracking of the needle insertion to display feedback for surgeons and to generate needle insertion plans ...

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      Mentions: Duke University
    18. Optical coherence refraction tomography

      Optical coherence refraction tomography

      Optical coherence tomography (OCT) is a cross-sectional, micrometre-scale imaging modality with widespread clinical application. Typical OCT systems sacrifice lateral resolution to achieve long depths of focus for bulk tissue imaging, and therefore tend to have better axial than lateral resolution. Such anisotropic resolution can obscure fine ultrastructural features. Furthermore, conventional OCT suffers from refraction-induced image distortions. Here, we introduce optical coherence refraction tomography (OCRT), which extends the superior axial resolution to the lateral dimension, synthesizing undistorted cross-sectional image reconstructions from multiple conventional images acquired with angular diversity. In correcting refraction-induced distortions to register the OCT images, OCRT also achieves spatially ...

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      Mentions: Duke University
    19. Ocular anterior chamber blood cell population differentiation using spectroscopic optical coherence tomography

      Ocular anterior chamber blood cell population differentiation using spectroscopic optical coherence tomography

      There is potential clinical significance in identifying cellular responses in the anterior chamber (AC) of the eye, which can indicate hyphema (an accumulation of red blood cells [RBCs]) or aberrant intraocular inflammation (an accumulation of white blood cells [WBCs]). In this work, we developed a spectroscopic OCT analysis method to differentiate between populations of RBCs and subtypes of WBCs, including granulocytes, lymphocytes and monocytes, both in vitro and in ACs of porcine eyes. We developed an algorithm to track single cells within OCT data sets, and extracted the backscatter reflectance spectrum of each single cell from the detected interferograms using ...

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      Mentions: Duke University
    20. Advances in Whole-Eye Optical Coherence Tomography Imaging

      Advances in Whole-Eye Optical Coherence Tomography Imaging

      Contemporary anterior segment and retinal optical coherence tomography (OCT) systems only image their particular designated region of the eye and cannot image both areas of the eye at once. This separation is due to the differences in optical system design needed to properly image the front or back of the eye and also due to limitations in the imaging depth of current commercial OCT systems. More recently, research and commercial OCT systems capable of "whole-eye" imaging have been described. These whole-eye OCT systems enable applications such as ocular biometry for cataract surgery, ocular shape analysis for myopia, and others. Further ...

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      Mentions: Duke University
    21. Depth-Based, Motion-Stabilized Colorization of Microscope-Integrated Optical Coherence Tomography Volumes for Microscope-Independent Microsurgery

      Depth-Based, Motion-Stabilized Colorization of Microscope-Integrated Optical Coherence Tomography Volumes for Microscope-Independent Microsurgery

      Purpose : We develop and assess the impact of depth-based, motion-stabilized colorization (color) of microscope-integrated optical coherence tomography (MIOCT) volumes on microsurgical performance and ability to interpret surgical volumes. Methods : Color was applied in real-time as gradients indicating axial position and stabilized based on calculated center of mass. In a test comparing colorization versus grayscale visualizations of prerecorded intraoperative volumes from human surgery, ophthalmologists ( N = 7) were asked to identify retinal membranes, the presence of an instrument, its contact with tissue, and associated deformation of the retina. In a separate controlled trial, trainees ( N = 15) performed microsurgical skills without conventional optical ...

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      Mentions: Duke University
    1-24 of 203 1 2 3 4 5 6 7 8 9 »
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