1. Articles from Oscar M. CARRASCO-ZEVALLOS

    1-20 of 20
    1. Controlling for Artifacts in Widefield Optical Coherence Tomography Angiography Measurements of Non-Perfusion Area

      Controlling for Artifacts in Widefield Optical Coherence Tomography Angiography Measurements of Non-Perfusion Area

      The recent clinical adoption of optical coherence tomography (OCT) angiography (OCTA) has enabled non-invasive, volumetric visualization of ocular vasculature at micron-scale resolutions. Initially limited to 3 mm × 3 mm and 6 mm × 6 mm fields-of-view (FOV), commercial OCTA systems now offer 12 mm × 12 mm, or larger, imaging fields. While larger FOVs promise a more complete visualization of retinal disease, they also introduce new challenges to the accurate and reliable interpretation of OCTA data. In particular, because of vignetting, wide-field imaging increases occurrence of low-OCT-signal artifacts, which leads to thresholding and/or segmentation artifacts, complicating OCTA analysis. This study presents ...

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    2. Feature of the Week 06/24/2018: Duke University Researchers Show Exciting Advances in Live OCT Volumes in Immersive Virtual Reality

      Feature of the Week 06/24/2018: Duke University Researchers Show Exciting Advances in Live OCT Volumes in Immersive Virtual Reality

      Virtual reality (VR) head-mounted displays are an attractive technology for viewing intrasurgical optical coherence tomography (OCT) volumes because they liberate surgeons from microscope oculars. We demonstrate real-time, interactive viewing of OCT volumes in a commercial HTC Vive immersive VR system using previously reported ray casting techniques. Furthermore, we show interactive manipulation and sectioning of volumes using handheld controllers and guidance of mock surgical procedures in porcine eyes exclusively within VR. To the best of our knowledge, we report the first immersive VR-OCT viewer with stereo ray casting volumetric renders, arbitrary sectioning planes, and live acquisition support. We believe VR-OCT volume ...

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    3. Real-time visualization and interaction with static and live optical coherence tomography volumes in immersive virtual reality

      Real-time visualization and interaction with static and live optical coherence tomography volumes in immersive virtual reality

      Virtual reality (VR) head-mounted displays are an attractive technology for viewing intrasurgical optical coherence tomography (OCT) volumes because they liberate surgeons from microscope oculars. We demonstrate real-time, interactive viewing of OCT volumes in a commercial HTC Vive immersive VR system using previously reported ray casting techniques. Furthermore, we show interactive manipulation and sectioning of volumes using handheld controllers and guidance of mock surgical procedures in porcine eyes exclusively within VR. To the best of our knowledge, we report the first immersive VR-OCT viewer with stereo ray casting volumetric renders, arbitrary sectioning planes, and live acquisition support. We believe VR-OCT volume ...

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    4. Volumetric Measurement of Subretinal Blebs Using Microscope-Integrated Optical Coherence Tomography

      Volumetric Measurement of Subretinal Blebs Using Microscope-Integrated Optical Coherence Tomography

      Purpose : We advance studies of subretinal treatments by developing a microscope-integrated optical coherence tomography (MIOCT) image-based method for measuring the volume of therapeutics delivered into the subretinal space. Methods : A MIOCT image-based volume measurement method was developed and assessed for accuracy and reproducibility by imaging an object of known size in model eyes. This method then was applied to subretinal blebs created by injection of diluted triamcinolone. Bleb volumes obtained from MIOCT were compared to the intended injection volume and the surgeon's estimation of leakage. Results : Validation of the image-based volume measurement method showed accuracy to ±1.0 μL ...

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    5. Development of Optical Coherence Tomography Systems for Ophthalmic Imaging and Intrasurgical Guidance

      Development of Optical Coherence Tomography Systems for Ophthalmic Imaging and Intrasurgical Guidance

      Ophthalmic microsurgery is one of the most commonly performed surgical procedures in the world and it necessitates precise three-dimensional manipulation of tissue at submillimeter spatial scales. As a result, ophthalmic surgeons require an operating microscope to perform surgery and to asses alterations to the tissue. Unfortunately, modern operating microscopes provide a limited en face perspective of the three-dimensional surgical field, and surgeons must infer depth information using stereoscopy and cannot directly visualize subsurface anatomy. These limitations may compromise the surgeon’s ability to maneuver instruments axially and to comprehensively evaluate the three-dimensional tissue structure. Optical coherence tomography (OCT) is a ...

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    6. Characterization of Long Working Distance Optical Coherence Tomography for Imaging of Pediatric Retinal Pathology

      Characterization of Long Working Distance Optical Coherence Tomography for Imaging of Pediatric Retinal Pathology

      Purpose : We determined the feasibility of fovea and optic nerve head imaging with a long working distance (LWD) swept source optical coherence tomography (OCT) prototype in adults, teenagers, and young children. Methods : A prototype swept source OCT system with a LWD (defined as distance from the last optical element of the imaging system to the eye) of 350 mm with custom fixation targets was developed to facilitate imaging of children. Imaging was performed in 49 participants from three age groups: 26 adults, 16 children 13 to 18 years old (teenagers), and seven children under 6 years old (young children) under ...

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    7. Microscope-Integrated Optical Coherence Tomography Angiography in the Operating Room in Young Children With Retinal Vascular Disease

      Microscope-Integrated Optical Coherence Tomography Angiography in the Operating Room in Young Children With Retinal Vascular Disease

      Importance Intraoperative optical coherence tomography (OCT) has gained traction as an important adjunct for clinical decision making during vitreoretinal surgery, and OCT angiography (OCTA) has provided novel insights in clinical evaluation of retinal diseases. To date, these two technologies have not been applied in combination to evaluate retinal vascular disease in the operating suite. Objective To conduct microscope-integrated, swept-source OCTA (MIOCTA) in children with retinal vascular disease. Design, Setting, and Participants In this case report analysis, OCT imaging in pediatric patients, MIOCTA images were obtained during examination under anesthesia from a young boy with a history of idiopathic vitreous hemorrhage ...

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    8. Review of intraoperative optical coherence tomography: technology and applications [Invited]

      Review of intraoperative optical coherence tomography: technology and applications [Invited]

      During microsurgery, en face imaging of the surgical field through the operating microscope limits the surgeon’s depth perception and visualization of instruments and sub-surface anatomy. Surgical procedures outside microsurgery, such as breast tumor resections, may also benefit from visualization of the sub-surface tissue structures. The widespread clinical adoption of optical coherence tomography (OCT) in ophthalmology and its growing prominence in other fields, such as cancer imaging, has motivated the development of intraoperative OCT for real-time tomographic visualization of surgical interventions. This article reviews key technological developments in intraoperative OCT and their applications in human surgery. We focus on handheld ...

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    9. Four-dimensional Microscope-Integrated Optical Coherence Tomography to Visualize Suture Depth in Strabismus Surgery

      Four-dimensional Microscope-Integrated Optical Coherence Tomography to Visualize Suture Depth in Strabismus Surgery

      The authors report the use of swept-source microscope-integrated optical coherence tomography (SS-MIOCT), capable of live four-dimensional (three-dimensional across time) intraoperative imaging, to directly visualize suture depth during lateral rectus resection. Key surgical steps visualized in this report included needle depth during partial and full-thickness muscle passes along with scleral passes.

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    10. Wide-field retinal optical coherence tomography with wavefront sensorless adaptive optics for enhanced imaging of targeted regions

      Wide-field retinal optical coherence tomography with wavefront sensorless adaptive optics for enhanced imaging of targeted regions

      The peripheral retina of the human eye offers a unique opportunity for assessment and monitoring of ocular diseases. We have developed a novel wide-field (>70°) optical coherence tomography system (WF-OCT) equipped with wavefront sensorless adaptive optics (WSAO) for enhancing the visualization of smaller (<25°) targeted regions in the peripheral retina. We iterated the WSAO algorithm at the speed of individual OCT B-scans (~20 ms) by using raw spectral interferograms to calculate the optimization metric. Our WSAO approach with a 3 mm beam diameter permitted primarily low- but also high- order peripheral wavefront correction in less than 10 seconds. In preliminary ...

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    11. Long working distance OCT with a compact 2f retinal scanning configuration for pediatric imaging

      Long working distance OCT with a compact 2f retinal scanning configuration for pediatric imaging

      Young and/or autistic children cannot be imaged with tabletop or handheld optical coherence tomography (OCT) because of their lack of attention and fear of large objects close to their face. We demonstrate a prototype retinal swept-source OCT system with a long working distance (from the last optical element to the subject’s eye) to facilitate pediatric imaging. To reduce the number of optical elements and axial length compared to the traditional 4

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    12. Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study

      Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study

      Purpose: To examine big-bubble (BB) formation success rates in deep anterior lamellar keratoplasty (DALK) at various corneal depths using real-time guidance from swept-source, microscope-integrated optical coherence tomography (SS-MIOCT). Methods: The DALK procedure was performed ex vivo with 34 human donor corneoscleral buttons on pressurized artificial anterior chambers using the BB technique employed by Anwar and Teichmann. We inserted a needle under controlled ex vivo conditions to corneal depths ranging from 40% to ≥90% using real-time guidance from SS-MIOCT and injected air. BB success was then determined for each injection. Results: The average needle depth for successful full BB formation was ...

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    13. Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography

      Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography

      Volumetric acquisition with anterior segment optical coherence tomography (ASOCT) is necessary to obtain accurate representations of the tissue structure and to account for asymmetries of the anterior eye anatomy. Additionally, recent interest in imaging of anterior segment vasculature and aqueous humor flow resulted in application of OCT angiography techniques to generate en face and 3D micro-vasculature maps of the anterior segment. Unfortunately, ASOCT structural and vasculature imaging systems do not capture volumes instantaneously and are subject to motion artifacts due to involuntary eye motion that may hinder their accuracy and repeatability. Several groups have demonstrated real-time tracking for motion-compensated in ...

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    14. Impact of Microscope-Integrated OCT on Ophthalmology Resident Performance of Anterior Segment Surgical Maneuvers in Model Eyes

      Impact of Microscope-Integrated OCT on Ophthalmology Resident Performance of Anterior Segment Surgical Maneuvers in Model Eyes

      Purpose : The integration of swept-source optical coherence tomography (SS-OCT) into the operating microscope enables real-time, tissue-level three-dimensional (3D) imaging to aid in ophthalmic microsurgery. In this prospective randomized controlled study, we evaluated the impact of SS microscope-integrated OCT (MI-OCT) on ophthalmology residents' performance of ophthalmic microsurgical maneuvers. Methods : Fourteen ophthalmology residents from a single institution were stratified by year of training and randomized to perform four anterior segment surgical maneuvers on porcine eyes with (MI-OCT+) or without (MI-OCT−) direct intraoperative OCT guidance. Subsequently, both groups repeated the same maneuvers without MI-OCT feedback to test whether initial MI-OCT experience affected subsequent ...

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    15. Optical Coherence Tomography for Retinal Surgery: Perioperative Analysis to Real-Time Four-Dimensional Image-Guided Surgery

      Optical Coherence Tomography for Retinal Surgery: Perioperative Analysis to Real-Time Four-Dimensional Image-Guided Surgery

      Magnification of the surgical field using the operating microscope facilitated profound innovations in retinal surgery in the 1970s, such as pars plana vitrectomy. Although surgical instrumentation and illumination techniques are continually developing, the operating microscope for vitreoretinal procedures has remained essentially unchanged and currently limits the surgeon's depth perception and assessment of subtle microanatomy. Optical coherence tomography (OCT) has revolutionized clinical management of retinal pathology, and its introduction into the operating suite may have a similar impact on surgical visualization and treatment. In this article, we review the evolution of OCT for retinal surgery, from perioperative analysis to live ...

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    16. Real-Time Microscope-Integrated OCT to Improve Visualization in DSAEK for Advanced Bullous Keratopathy

      Real-Time Microscope-Integrated OCT to Improve Visualization in DSAEK for Advanced Bullous Keratopathy

      Purpose: To report the intraoperative use of microscope-integrated optical coherence tomography (MIOCT) to enable visualization for Descemet's stripping automated endothelial keratoplasty (DSAEK) in 2 patients with advanced bullous keratopathy. Methods: Patient 1 was an 83-year-old female and patient 2 was a 28-year-old male both with limited vision and significant pain from bullous keratopathy who underwent palliative DSAEK. Because of the severity and chronicity of the corneal decompensation in both patients, the view past the anterior cornea was negligible using standard microscope illumination techniques. We used spectral-domain (Patient 1) and swept-source (Patient 2) MIOCT, both of which rely on infrared ...

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    17. Systems And Methods For Eye Tracking For Motion Corrected Ophthalmic Optical Coherenece Tomography

      Systems And Methods For Eye Tracking For Motion Corrected Ophthalmic Optical Coherenece 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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    1-20 of 20
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  2. Topics in the News

    1. (19 articles) Duke University
    2. (19 articles) Oscar Carrasco-Zevallos
    3. (18 articles) Joseph A. Izatt
    4. (13 articles) Cynthia A. Toth
    5. (9 articles) Anthony N. Kuo
    6. (4 articles) Sina Farsiu
    7. (3 articles) Mark Draelos
    8. (1 articles) Massachusetts Institute of Technology
    9. (1 articles) James G. Fujimoto
    10. (1 articles) Andre J. Witkin
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    Systems And Methods For Eye Tracking For Motion Corrected Ophthalmic Optical Coherenece Tomography Real-Time Microscope-Integrated OCT to Improve Visualization in DSAEK for Advanced Bullous Keratopathy Impact of Microscope-Integrated OCT on Ophthalmology Resident Performance of Anterior Segment Surgical Maneuvers in Model Eyes Pupil Tracking for Real-Time Motion Corrected Anterior Segment Optical Coherence Tomography Intraoperative 4-Dimensional Microscope-Integrated Optical Coherence Tomography-Guided 27-Gauge Transvitreal Choroidal Biopsy for Choroidal Melanoma Needle Depth and Big-Bubble Success in Deep Anterior Lamellar Keratoplasty: An Ex Vivo Microscope-Integrated OCT Study Long working distance OCT with a compact 2f retinal scanning configuration for pediatric imaging Microscope-Integrated Optical Coherence Tomography Angiography in the Operating Room in Young Children With Retinal Vascular Disease Real-time visualization and interaction with static and live optical coherence tomography volumes in immersive virtual reality Feature of the Week 06/24/2018: Duke University Researchers Show Exciting Advances in Live OCT Volumes in Immersive Virtual Reality AI-Assisted In Situ Detection of Human Glioma Infiltration Using a Novel Computational Method for Optical Coherence Tomography Motorized capsule for shadow-free OCT imaging and synchronous beam control