All Articles from David Huang -Optical Coherence Tomography News

Articles from David Huang

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1. Cognitive decline in older adults: What can we learn from optical coherence tomography (OCT)-based retinal vascular imaging?
  
  Explore American Geriatrics Society May 20 2021 Neurology , Ophthalmology
  
  Introduction: Accumulated vascular damage contributes to the onset and progression of vascular dementia and possibly to Alzheimer's disease. Here we evaluate the feasibility and utility of using retinal imaging of microvascular markers to identify older adults at risk of cognitive disease. Methods: The "Eye Determinants of Cognition" (EyeDOC) study recruited a biracial, population-based sample of participants from two sites: Jackson, MS, and Washington Co, MD. Optical coherence tomographic angiography (OCTA) was used to capture vessel density (VD) from a 6 × 6 mm scan of the macula in several vascular layers from 2017 to 2019. The foveal avascular zone (FAZ ...
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  Mentions: Johns Hopkins University Oregon Health & Science University
2. High-speed and widefield handheld swept-source OCT angiography with a VCSEL light source
  
  Explore OSA | OSA Publishing May 20 2021 Ophthalmology , Probes
  
  Optical coherence tomography (OCT) and OCT angiography (OCTA) enable noninvasive structural and angiographic imaging of the eye. Portable handheld OCT/OCTA systems are required for imaging patients in the supine position. Examples include infants in the neonatal intensive care unit (NICU) and operating room (OR). The speed of image acquisition plays a pivotal role in acquiring high-quality OCT/OCTA images, particularly with the handheld system, since both the operator hand tremor and subject motion can cause significant motion artifacts. In addition, having a large field of view and the ability of real-time data visualization are critical elements in rapid disease ...
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  Mentions: National Institutes of Health Oregon Health & Science University Center for Ophthalmic Optics and Lasers
3. Comparison of Central Macular Fluid Volume With Central Subfield Thickness in Patients With Diabetic Macular Edema Using Optical Coherence Tomography Angiography
  
  Explore The JAMA Network May 15 2021 Ophthalmology
  
  Importance: Diabetic macular edema (DME) is the predominant cause of visual impairment in patients with type 1 or 2 diabetes. Automated fluid volume measurements using optical coherence tomography (OCT) may improve the diagnostic accuracy of DME screening. Objective: To assess the diagnostic accuracy of an automated central macular fluid volume (CMFV) quantification using OCT for DME. Design, setting, and participants: A cross-sectional observational study was conducted at a tertiary academic center among 215 patients with diabetes (1 eye each) enrolled from January 26, 2015, to December 23, 2019. All participants underwent comprehensive examinations, 6 × 6-mm macular structural OCT horizontal raster ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
4. Optical coherence tomography angiography methods
  
  Explore uspto.gov Feb 23 2021 Ophthalmology , Patents
  
  Methods of applying OCT angiography are disclosed. In particular, methods of detecting, visualizing and measuring the extent of retinal neovascularization are disclosed. Further disclosed are methods measuring retinal nonperfusion area and choriocapillaris defect area.
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
5. Plexus-specific retinal vascular anatomy and pathologies as seen by projection-resolved optical coherence tomographic angiography
  
  Explore ScienceDirect Jan 22 2021 Ophthalmology
  
  Optical coherence tomographic angiography (OCTA) is a novel technology capable of imaging retinal vasculature three-dimensionally at capillary scale without the need to inject any extrinsic dye contrast. However, projection artifacts cause superficial retinal vascular patterns to be duplicated in deeper layers, thus interfering with the clean visualization of some retinal plexuses and vascular pathologies. Projection-resolved OCTA (PR-OCTA) uses post-processing algorithms to reduce projection artifacts. With PR-OCTA, it is now possible to resolve up to 4 distinct retinal vascular plexuses in the living human eye. The technology also allows us to detect and distinguish between various retinal and optic nerve diseases ...
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  Mentions: Center for Ophthalmic Optics and Lasers
6. Plexus-specific retinal capillary avascular area in exudative age-related macular degeneration with projection-resolved OCT angiography
  
  Explore BJO Online Dec 26 2020 Ophthalmology
  
  Objective To detect the plexus-specific retinal capillary avascular area in exudative age-related macular degeneration (EAMD) with projection-resolved optical coherence tomography angiography (PR-OCTA). Methods and analysis In this prospective cross-sectional single centre study, eyes with treatment-naïve EAMD underwent macular 3×3 mm OCTA with AngioVue system. OCTA scans were analysed and processed including three-dimensional projection artefact removal, retinal layer semi-automated segmentation and en face angiogram generation. Automated quantification of extrafoveal (excluding the central 1 mm circle) avascular area (EAA) were calculated on projection-resolved superficial vascular complex (SVC), intermediate capillary plexus (ICP) and deep capillary plexus (DCP), respectively. Results Nineteen eyes ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
7. Optical Instrumentation Position Opening at Oregon Health & Science University
  
  Explore Optical Coherence Tomography News Dec 21 2020 Jobs & Studentships
  
  Two postdoctoral research fellowship/research associate positions are 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 project in the field of optical imaging and image processing. Ph.D. in Optics, Biomedical Engineering, Electrical Engineering, Computing Science or a related field is required. Demonstrated excellence in one or more of the following areas is preferred: 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 programming ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
8. Keratoconus Detection using OCT Corneal and Epithelial Thickness Map Parameters and Patterns
  
  Explore LWW Online Nov 13 2020 Ophthalmology
  
  Purpose: To detect keratoconus using optical coherence tomography (OCT) corneal map parameters and patterns. Setting: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA DESIGN:: Cross-sectional observational study. Methods: A spectral-domain OCT was used to acquire corneal and epithelial thickness maps in normal, manifest keratoconic, subclinical keratoconic, and forme fruste keratoconic (FFK) eyes. A two-step decision tree was designed. An eye will be classified as keratoconus if both decision tree conditions are met: First, at least one of the four quantitative corneal thickness (minimum, minimum-maximum, superonasal-inferotemporal) and epithelial thickness (standard deviation) map parameters exceed cutoff values. Second, presence of ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
9. A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps
  
  Explore Healio.com Nov 12 2020 Ophthalmology
  
  PURPOSE: To develop a coincident thinning (CTN) index to differentiate between keratoconic and healthy corneas using optical coherence tomography (OCT) measurements of pachymetry and epithelial thickness. METHODS: Pattern deviation maps of pachymetry and epithelial thickness were generated using Fourier-domain OCT images of the cornea. The co-localized thinning of the two maps was quantified using a novel CTN index, which was calculated from Gaussian fits of the regions of maximum relative thinning. The CTN index was validated using k-fold cross-validation, and its classification performance was compared to minimum pachymetry and maximum keratometry. RESULTS: A total of 82 normal eyes and 133 ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
10. Split-spectrum amplitude-decorrelation angiography with optical coherence tomography
  
  Explore OSA | OSA Publishing Aug 4 2020
  
  Amplitude decorrelation measurement is sensitive to transverse flow and immune to phase noise in comparison to Doppler and other phase-based approaches. However, the high axial resolution of OCT makes it very sensitive to the pulsatile bulk motion noise in the axial direction. To overcome this limitation, we developed split-spectrum amplitude-decorrelation angiography (SSADA) to improve the signal-to-noise ratio (SNR) of flow detection. The full OCT spectrum was split into several narrower bands. Inter-B-scan decorrelation was computed using the spectral bands separately and then averaged. The SSADA algorithm was tested on in vivo images of the human macula and optic nerve head ...
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  Mentions: Massachusetts Institute of Technology Thorlabs Oregon Health & Science University
11. Sensorless adaptive-optics optical coherence tomographic angiography
  
  Explore OSA | OSA Publishing Jul 1 2020
  
  Optical coherence tomographic angiography (OCTA) can image the retinal blood flow but visualization of the capillary caliber is limited by the low lateral resolution. Adaptive optics (AO) can be used to compensate ocular aberrations when using high numerical aperture (NA), and thus improve image resolution. However, previously reported AO-OCTA instruments were large and complex, and have a small sub-millimeter field of view (FOV) that hinders the extraction of biomarkers with clinical relevance. In this manuscript, we developed a sensorless AO-OCTA prototype with an intermediate numerical aperture to produce depth-resolved angiograms with high resolution and signal-to-noise ratio over a 2 × 2 ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers Simon Fraser University
12. Depth-resolved optimization of a real-time sensorless adaptive optics optical coherence tomography
  
  Explore OSA | OSA Publishing May 2 2020
  
  Sensorless adaptive optics optical coherence tomography (AO-OCT) is a technology to image retinal tissue with high resolution by compensating ocular aberrations without wavefront sensors. In this Letter, a fast and robust hill-climbing algorithm is developed to optimize five Zernike modes in AO-OCT with a numerical aperture between that of conventional AO and commercial OCT systems. The merit function is generated in real time using graphics processing unit while axially tracking the retinal layer of interest. A new method is proposed to estimate the largest achievable field of view for which aberrations are corrected uniformly in sensorless AO-OCT.
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
13. Optical coherence tomography angiography avascular area association with one-year treatment requirement and disease progression in diabetic retinopathy
  
  Explore American Journal of Ophthalmology Apr 29 2020 Ophthalmology
  
  Purpose To assess the association between optical coherence tomography angiography (OCTA) quantified avascular areas (AA) and diabetic retinopathy (DR) severity, progression and treatment requirement in the following year. Design Prospective cohort study. Methods We recruited diabetic patients from tertiary academic retina practice and obtained 3x3-mm macular OCTA scans with AngioVue system and standard 7-field color photographs at baseline and 1-year visit. A masked grader determined the DR severity from the color photographs using the Early Treatment of Diabetic Retinopathy (ETDRS) scale. A custom algorithm detected extrafoveal AA (EAA) excluding the central 1mm circle in projection-resolved superficial vascular complex (SVC), intermediate ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
14. Bulk motion subtraction in optical coherence tomography angiography
  
  Explore uspto.gov Mar 17 2020 Ophthalmology , Patents
  
  Described herein is an algorithm to remove decorrelation noise due to bulk motion in optical coherence tomography angiography (OCTA). OCTA B-frames are divided into segments within which the bulk motion velocity could be assumed constant. This velocity is recovered using linear regression of decorrelation versus the logarithm of reflectance in axial lines (A-lines) identified as bulk tissue by percentile analysis. The fitting parameters are used to calculate a reflectance-adjusted threshold for bulk motion decorrelation. Below this threshold, voxels are identified as non-flow tissue, and their flow values are set to zeros. Above this threshold, the voxels are identified as flow ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
15. Application of Corneal Optical Coherence Tomography Angiography for Assessment of Vessel Depth in Corneal Neovascularization
  
  Explore LWW Online Dec 28 2019 Ophthalmology
  
  Purpose: To map and measure the depths of corneal neovascularization (NV) using 3-dimensional optical coherence tomography angiography (OCTA) at 2 different wavelengths. Methods: Corneal NV of varying severity, distribution, and underlying etiology was examined. Average NV depth and vessel density were measured using 840-nm spectral-domain OCTA and 1050-nm swept-source OCTA. The OCTA results were compared with clinical slit-lamp estimation of NV depth. Results: Twelve eyes with corneal NV from 12 patients were imaged with OCTA. Clinically “superficial,” “midstromal,” and “deep” cases had an average vessel depth of 23%, 39%, and 66% on 1050-nm OCTA, respectively. Average vessel depth on OCTA ...
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  Mentions: Massachusetts Institute of Technology Oregon Health & Science University Center for Ophthalmic Optics and Lasers
16. Estimating Visual Field Mean Deviation using Optical Coherence Tomographic Nerve Fiber Layer Measurements in Glaucoma Patients
  
  Explore Nature Publishing Group Dec 10 2019 Ophthalmology
  
  To construct an optical coherence tomography (OCT) nerve fiber layer (NFL) parameter that has maximal correlation and agreement with visual field (VF) mean deviation (MD). The NFL_MD parameter in dB scale was calculated from the peripapillary NFL thickness profile nonlinear transformation and VF area-weighted averaging. From the Advanced Imaging for Glaucoma study, 245 normal, 420 pre-perimetric glaucoma (PPG), and 289 perimetric glaucoma (PG) eyes were selected. NFL_MD had significantly higher correlation (Pearson R: 0.68 vs 0.55, p < 0.001) with VF_MD than the overall NFL thickness. NFL_MD also had significantly higher sensitivity in detecting PPG (0.14 vs ...
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  Mentions: Oregon Health & Science University University of Miami Center for Ophthalmic Optics and Lasers
17. Sectorwise Visual Field Simulation Using Optical Coherence Tomographic Angiography Nerve Fiber Layer Plexus Measurements in Glaucoma
  
  Explore ScienceDirect Nov 29 2019 Ophthalmology
  
  Purpose To simulate 24-2 visual field (VF) using optical coherence tomographic angiography (OCTA) for glaucoma evaluation. Design Cross-sectional study. Methods One eye each of 39 glaucoma and 31 age-matched normal participants was scanned using 4.5-mm OCTA scans centered on the disc. The peripapillary retinal nerve fiber layer plexus capillary density (NFLP_CD, %area) was measured. The NFLP_CD and 24-2 VF maps were divided into 8 corresponding sectors using an extension of Garway-Heath scheme. Results Sector NFLP_CD was transformed to a logarithmic dB scale and converted to sector simulated VF deviation maps. Comparing simulated and actual 24-2 VF maps, the worst ...
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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
18. Measuring Glaucomatous Focal Perfusion Loss in the Peripapillary Retina using Optical Coherence Tomographic Angiography
  
  Explore Ophthalmology Nov 12 2019 Ophthalmology
  
  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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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
19. The Bruno Lumbroso Lecture at the 7th International Congress on OCT Angiography
  
  Explore Optical Coherence Tomography News Oct 18 2019 Ophthalmology
  
  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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  Mentions: Oregon Health & Science University University of Miami Srinivas R. Sadda
20. Automated quantification of nonperfusion in the retina using optical coherence tomography angiography
  
  Explore uspto.gov Oct 1 2019 Ophthalmology , Patents
  
  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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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
21. Detecting and measuring areas of choriocapillaris low perfusion in intermediate, non-neovascular age-related macular degeneration
  
  Explore SPIE Digital Library Sep 17 2019 Ophthalmology
  
  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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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
22. Detection of reduced retinal vessel density in eyes with geographic atrophy secondary to age-related macular degeneration using projection-resolved optical coherence tomography angiography
  
  Explore American Journal of Ophthalmology Sep 14 2019 Ophthalmology
  
  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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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
23. Automated segmentation of peripapillary retinal boundaries in OCT combining a convolutional neural network and a multi-weights graph search
  
  Explore OSA | OSA Publishing Aug 29 2019
  
  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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  Mentions: Oregon Health & Science University
24. Monitoring retinal responses to acute intraocular pressure elevation in rats with visible light optical coherence tomography
  
  Explore SPIE Digital Library Jul 18 2019 Ophthalmology
  
  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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  Mentions: Oregon Health & Science University Center for Ophthalmic Optics and Lasers
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