1. Articles from David Huang

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    1. Measuring Glaucomatous Focal Perfusion Loss in the Peripapillary Retina using Optical Coherence Tomographic Angiography

      Measuring Glaucomatous Focal Perfusion Loss in the Peripapillary Retina using Optical Coherence Tomographic Angiography

      Purpose To measure low perfusion areas (LPA) and focal perfusion loss (FPL) in the peripapillary retina using optical coherence tomographic angiography (OCTA) in glaucoma. Design Prospective observation study. Participants Forty-seven primary open angle glaucoma (POAG) patients and 36 normal subjects were analyzed. Methods One eye of each subject was scanned using AngioVue 4.5-mm OCTA scan centered on the disc. En face nerve fiber layer plexus angiogram was generated. Using custom software, capillary density map was obtained by computing the fraction of area occupied by flow pixels within each superpixel containing 21×21-pixels. The low-perfusion map is defined by local ...

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    2. The Bruno Lumbroso Lecture at the 7th International Congress on OCT Angiography

      The Bruno Lumbroso Lecture at the 7th International Congress on OCT Angiography

      Dear Colleagues: As you know, the International Congress on OCT Angiography, En Face OCT and Advances in OCT that Professor Bruno Lumbroso initiated few years ago will be in its 7th Year this December 2019 in Rome. Certainly, this global Congress has become one of the most successful, most-attended, and most educational meetings in the field of retinal imaging. Every December during the past six years, more than 1,000 of us have enjoyed spending few days in Rome learning the latest advances in retinal imaging, from OCT to OCTA to adaptive optics to microperimetry, among others, and meeting new ...

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    3. Automated quantification of nonperfusion in the retina using optical coherence tomography angiography

      Automated quantification of nonperfusion in the retina using optical coherence tomography angiography

      Disclosed are methods and systems for measuring areas of nonperfusion in the retina using OCT imaging. The disclosed methods and systems allow for the automated segmentation and quantification of avascular areas of the retina utilizing information obtained from both structural OCT and OCT angiography (OCTA) data. The disclosed methods include filtering approaches which enhance vessel structure while suppressing noise, dynamic thresholding approaches to mitigate the detrimental effects of within-scan variability and low scan quality, and distance transform-based approaches to improve detection of ischemic regions. When combined with methods such as projection-resolved OCTA, the sensitivity to detect nonperfusion within different plexuses ...

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    4. Detecting and measuring areas of choriocapillaris low perfusion in intermediate, non-neovascular age-related macular degeneration

      Detecting and measuring areas of choriocapillaris low perfusion in intermediate, non-neovascular age-related macular degeneration

      Age-related macular degeneration (AMD) is a vision-threatening disease that affects the outer retina and choroid of elderly adults. Because photoreceptors are found in the outer retina and rely primarily on the trophic support of the underlying choriocapillaris, imaging of flow or lack thereof in choriocapillaris by optical coherence tomography angiography (OCTA) has great clinical potential in AMD assessment. We introduce a metric using OCTA, named “focal perfusion loss” (FPL) to describe the effects of age and non-neovascular AMD on choriocapillaris flow. Because OCTA imaging of choriocapillaris is vulnerable to artifacts—namely motion, projections, segmentation errors, and shadows—they are removed ...

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    5. Detection of reduced retinal vessel density in eyes with geographic atrophy secondary to age-related macular degeneration using projection-resolved optical coherence tomography angiography

      Detection of reduced retinal vessel density in eyes with geographic atrophy secondary to age-related macular degeneration using projection-resolved optical coherence tomography angiography

      Purpose To compare retinal vessel density in eyes with geographic atrophy (GA) secondary to age-related macular degeneration (AMD) to age-matched healthy eyes using projection-resolved optical coherence tomography angiography (PR-OCTA). Design Prospective cross-sectional study. Methods Study participants underwent macular 3×3-mm OCTA scans with spectral domain OCTA. Reflectance-compensated retinal vessel densities were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP). Quantitative analysis using normalized deviation compared the retinal vessel density in GA regions, 500 μm GA rim regions, and non-GA regions to similar macular locations in control eyes. Results Ten eyes with GA ...

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    6. Automated segmentation of peripapillary retinal boundaries in OCT combining a convolutional neural network and a multi-weights graph search

      Automated segmentation of peripapillary retinal boundaries in OCT combining a convolutional neural network and a multi-weights graph search

      Quantitative analysis of the peripapillary retinal layers and capillary plexuses from optical coherence tomography (OCT) and OCT angiography images depend on two segmentation tasks – delineating the boundary of the optic disc and delineating the boundaries between retinal layers. Here, we present a method combining a neural network and graph search to perform these two tasks. A comparison of this novel method’s segmentation of the disc boundary showed good agreement with the ground truth, achieving an overall Dice similarity coefficient of 0.91 ± 0.04 in healthy and glaucomatous eyes. The absolute error of retinal layer boundaries segmentation in the ...

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    7. Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography

      Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography

      Elevated intraocular pressure (IOP) is an important risk factor for glaucoma. However, the role of IOP in glaucoma progression, as well as retinal physiology in general, remains incompletely understood. We demonstrate the use of visible light optical coherence tomography to measure retinal responses to acute IOP elevation in Brown Norway rats. We monitored retinal responses in reflectivity, angiography, blood flow, oxygen saturation (sO2 ), and oxygen metabolism over a range of IOP from 10 to 100 mmHg. As IOP was elevated, nerve fiber layer reflectivity was found to decrease. Vascular perfusion in the three retinal capillary plexuses remained steady until IOP ...

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    8. International Ocular Circulation Society Inaugural Meeting, August 10, 2019 Portland Oregon

      International Ocular Circulation Society Inaugural Meeting, August 10, 2019 Portland Oregon

      The International Ocular Circulation Society (IOCS) was co-founded by a group of leading researchers in America, Asia, and Europe in 2018. The inaugural meeting of the new Society will be hosted by David Huang, M.D. and Yali Jia, Ph.D. of the Casey Eye Institute in Portland Oregon on August 10, 2019. The meeting will present 28 papers and 35 posters on technologies on the topics of imaging and measurement of ocular blood flow and oxygen metabolism, vascular anatomy and physiology, and the roles of ocular circulation in retina, optic nerve, neurological, and systemic diseases. The Oregon Health & Science ...

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    9. Correlation of Outer Retinal Degeneration and Choriocapillaris Loss in Stargardt Disease Using En Face Optical Coherence Tomography and Optical Coherence Tomography Angiography

      Correlation of Outer Retinal Degeneration and Choriocapillaris Loss in Stargardt Disease Using En Face Optical Coherence Tomography and Optical Coherence Tomography Angiography

      Purpose This study measured and correlated degeneration of the junction between the inner and outer segments (IS/OS), the retinal pigment epithelium (RPE), and the choriocapillaris (CC) in Stargardt disease (STGD). Design Prospective cross-sectional study. Methods This study was conducted at the Casey Eye Institute. A total of 23 patients with STGD were enrolled and underwent optical coherence tomography angiography (OCTA). Scans were centered on the fovea. OCT slab projections and en face boundary maps were used to create masks to measure total IS/OS loss or RPE atrophy as well as regions of isolated IS/OS loss, isolated RPE ...

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    10. Signal strength reduction effects in optical coherence tomographic angiography

      Signal strength reduction effects in optical coherence tomographic angiography

      Objective To elucidate the relationship between vessel density (VD) measurements and signal strength in optical coherence tomography angiography (OCTA). Design Cross-sectional study. Subjects: Healthy volunteers. Methods OCTA images obtained from healthy volunteers were analyzed to demonstrate the relationship between signal strength index (SSI) and VD. Experiments were performed to determine the effects of signal strength reduction on VD measurements on the Optovue/AngioVue and Cirrus/AngioPlex OCTA systems. Signal strength reduction was generated by either neutral density filters (NDF) or defocus. Main Outcome Measures Regression analysis of signal strength effects on VD. Results VD decreased linearly with signal strength with ...

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    11. Maximum value projection produces better en face OCT angiograms than mean value projection

      Maximum value projection produces better en face OCT angiograms than mean value projection

      Optical coherence tomography angiography (OCTA) images rely on en face data projections for both qualitative and quantitative interpretation. Both maximum value and mean value projections are commonly used, and many researchers consider them essentially interchangeable approaches. On the contrary, we find that maximum value projection achieves a consistently higher signal-to-noise ratio and higher image contrast across multiple vascular layers, in both healthy eyes and for each disease examined.

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    12. Detection of Non-exudative Choroidal Neovascularization and Progression to Exudative Choroidal Neovascularization Using Optical Coherence Tomography Angiography

      Detection of Non-exudative Choroidal Neovascularization and Progression to Exudative Choroidal Neovascularization Using Optical Coherence Tomography Angiography

      Objective To detect non-exudative choroidal neovascularization (CNV) in age-related macular degeneration with optical coherence tomography angiography (OCTA) and determine risk of developing exudative CNV compared to eyes without non-exudative CNV. Design Prospective longitudinal observational study Participants Consecutive patients with drusen and pigmentary changes in the study eye and exudative neovascular AMD in the fellow eye. Methods Study participants underwent spectral domain OCTA (AngioVue, Optovue, Inc), clinical exam, and structural OCT at baseline and six-month intervals for two years. OCTA images were exported for custom processing to remove projection artifact and calculate CNV vessel area. Main Outcome Rate of developing exudation ...

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    13. Real-time cross-sectional and en face OCT angiography guiding high-quality scan acquisition

      Real-time cross-sectional and en face OCT angiography guiding high-quality scan acquisition

      Defocusing, vignetting, and bulk motion degrade the image quality of optical coherence tomography angiography (OCTA) more significantly than structural OCT. The assessment of focus, alignment conditions, and stability of imaging subjects in commercially available OCTA systems are currently based on OCT signal quality alone, without knowledge of OCTA signal quality. This results in low yield rates for further quantification. In this Letter, we developed a novel OCTA platform based on a graphics processing unit (GPU) for a real-time, high refresh rate, B-san-by-B-scan split-spectrum amplitude-decorrelation angiography. The GPU provides a real-time display of both cross-sectional and en face images to assist ...

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    14. Visual Optics Postdoctoral/Research Fellow Opening at Oregon Health & Science University

      Visual Optics Postdoctoral/Research Fellow Opening at Oregon Health & Science University

      A postdoctoral research fellow position is available in the Center for Ophthalmic Optics & Lasers Lab ( www.coollab.net ), Casey Eye Institute, Oregon Health & Science University. This is an outstanding opportunity for a candidate to use optical coherence tomography to conduct visual optics research in an academic ophthalmology setting. The researcher on this position will work with a team of scientists, engineers and physicians to develop ultrahigh-performance OCT systems for comprehensive optical characterization of the anterior eye and wide-field ocular surface topography, to improve post-refractive surgery intraocular lens power calculation, therapeutic scleral lens design, diagnosis and classification of corneal shape irregularities ...

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    15. DETECTION OF CLINICALLY UNSUSPECTED RETINAL NEOVASCULARIZATION WITH WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      DETECTION OF CLINICALLY UNSUSPECTED RETINAL NEOVASCULARIZATION WITH WIDE-FIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To evaluate wide-field optical coherence tomography angiography (OCTA) for detection of clinically unsuspected neovascularization (NV) in diabetic retinopathy (DR). Methods: This prospective observational single-center study included adult patients with a clinical diagnosis of nonproliferative DR. Participants underwent a clinical examination, standard 7-field color photography, and OCTA with commercial and prototype swept-source devices. The wide-field OCTA was achieved by montaging five 6 × 10-mm scans from a prototype device into a 25 × 10-mm image and three 6 × 6-mm scans from a commercial device into a 15 × 6-mm image. A masked grader determined the retinopathy severity from color photographs. Two trained readers ...

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    16. Automated detection of shadow artifacts in optical coherence tomography angiography

      Automated detection of shadow artifacts in optical coherence tomography angiography

      Frequently, when imaging retinal vasculature with optical coherence tomography angiography (OCTA) in diseased eyes, there are unavoidable obstacles to the propagation of light such as vitreous floaters or the pupil boundary. These obstacles can block the optical coherence tomography (OCT) beam and impede the visualization of the underlying retinal microcirculation. Detecting these shadow artifacts is especially important in the quantification of metrics that assess retinal disease progression because they might masquerade as regional perfusion loss. In this work, we present an algorithm to identify shadowed areas in OCTA of healthy subjects as well as patients with diabetic retinopathy, uveitis and ...

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    17. Systems and methods for retinal layer segmentation in OCT imaging and OCT angiography

      Systems and methods for retinal layer segmentation in OCT imaging and OCT angiography

      Disclosed herein are methods and systems for segmenting, visualizing, and quantifying the layered structure of retina in optical coherence tomography datasets. The disclosed methods have particular application to OCT angiography data, where specific retina layers have distinct vascular structures and characteristics that can be altered in various pathological conditions of the eye.

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    18. Rodent retinal circulation organization and oxygen metabolism revealed by visible-light optical coherence tomography

      Rodent retinal circulation organization and oxygen metabolism revealed by visible-light optical coherence tomography

      Visible light optical coherence tomography (vis-OCT) is an emerging label-free and high-resolution 3-dimensional imaging technique that can provide retinal oximetry, angiography, and flowmetry in one modality. In this paper, we studied the organization of the arterial and venous retinal circulation in rats using vis-OCT. Arterioles were found predominantly in the superficial vascular plexus whereas veins tended to drain capillaries from the deep capillary plexus. After that, we determined the oxygen metabolic rate supported by retinal microcirculation by combining retinal vessel oxygen saturation and blood flow measurements. The ability to visualize and monitor retinal circulation organization and oxygen metabolism by vis-OCT ...

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    19. Quantitative evaluation of retinal artery occlusion using optical coherence tomography angiography: A case report

      Quantitative evaluation of retinal artery occlusion using optical coherence tomography angiography: A case report

      Rationale: Retinal artery occlusion (RAO) results in painless, catastrophic vision loss in a period of seconds. Optical coherence tomography angiography (OCTA) can image retinal microcirculation, which is helpful to evaluate treatment response during the follow-up period. Using a single case with central RAO, we report its retinal perfusion changes before and after treatment using OCTA. Patient concerns: A 36-year-old Chinese man came to our clinic with a sudden, painless loss of vision (hand motion) in his left eye. A vasodilator (nicotinic acid) was used as the primary treatment. OCTA imaging and a visual field examination were performed to assess the ...

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    20. Postdoctoral Fellowship/Research Associate Position at the Casey Eye Institute, Oregon Health & Science University

      Postdoctoral Fellowship/Research Associate Position at the Casey Eye Institute, Oregon Health & Science University

      A postdoctoral research fellowship/research associate position is immediately available in the Center for Ophthalmic Optics and Lasers www.COOLLab.net , Casey Eye Institute, Oregon Health & Science University. The fellowship will focus on interdisciplinary projects in the field of optical imaging and real-time image processing. Ph.D. in Optics, Biomedical Engineering, Electrical Engineering, Computer Science or a related field is required. Demonstrated excellence in one or more of the following areas is required: expertise in optical coherence Tomography, scanning laser ophthalmoscope and adaptive optics, optical/electrical system design, prototyping and simulation, data acquisition and system control/synchronization, and C++/GPU ...

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    21. Automated segmentation of retinal layer boundaries and capillary plexuses in wide-field optical coherence tomographic angiography

      Automated segmentation of retinal layer boundaries and capillary plexuses in wide-field optical coherence tomographic angiography

      Advances in the retinal layer segmentation of structural optical coherence tomography (OCT) images have allowed the separation of capillary plexuses in OCT angiography (OCTA). With the increased scanning speeds of OCT devices and wider field images (≥10 mm on fast-axis), greater retinal curvature and anatomic variations have introduced new challenges. In this study, we developed a novel automated method to segment seven retinal layer boundaries and two retinal plexuses in wide-field OCTA images. The algorithm was initialized by a series of points forming a guidance point array that estimates the location of retinal layer boundaries. A guided bidirectional graph search ...

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    22. Classification of Choroidal Neovascularization Using Projection-Resolved Optical Coherence Tomographic Angiography

      Classification of Choroidal Neovascularization Using Projection-Resolved Optical Coherence Tomographic Angiography

      Purpose : To evaluate if projection-resolved optical coherence tomographic angiography (PR-OCTA) reduces projection artifact with less attenuation of choroidal neovascularization (CNV) flow signal compared to conventional OCTA with slab subtraction. Methods : In this retrospective cross-sectional study, participants with subfoveal treatment-naïve CNV secondary to age-related macular degeneration underwent OCTA. Scans were exported for custom processing including manual segmentation as necessary, application of slab subtraction and PR-OCTA algorithm, and calculation of CNV vascular area and connectivity. CNV was classified as type 1, minimally type 2, or predominantly type 2 based on fluorescein angiography (FA) and OCT. Two masked retina specialists independently classified ...

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    23. Deep learning for the segmentation of preserved photoreceptors on en face optical coherence tomography in two inherited retinal diseases

      Deep learning for the segmentation of preserved photoreceptors on en face optical coherence tomography in two inherited retinal diseases

      The objective quantification of photoreceptor loss in inherited retinal degenerations (IRD) is essential for measuring disease progression, and is now especially important with the growing number of clinical trials. Optical coherence tomography (OCT) is a non-invasive imaging technology widely used to recognize and quantify such anomalies. Here, we implement a versatile method based on a convolutional neural network to segment the regions of preserved photoreceptors in two different IRDs (choroideremia and retinitis pigmentosa) from OCT images. An excellent segmentation accuracy (~90%) was achieved for both IRDs. Due to the flexibility of this technique, it has potential to be extended to ...

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    1-24 of 231 1 2 3 4 5 6 7 8 9 10 »
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    1. (231 articles) David Huang
    2. (214 articles) Center for Ophthalmic Optics and Lasers
    3. (183 articles) Oregon Health & Science University
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    5. (64 articles) University of Southern California
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    7. (40 articles) Optovue
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