1. Articles from Yali Jia

    1-24 of 99 1 2 3 4 5 »
    1. Sectorwise Visual Field Simulation Using Optical Coherence Tomographic Angiography Nerve Fiber Layer Plexus Measurements in Glaucoma

      Sectorwise Visual Field Simulation Using Optical Coherence Tomographic Angiography Nerve Fiber Layer Plexus Measurements in Glaucoma

      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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    2. Quantification of local circulation with OCT angiography

      Quantification of local circulation with OCT angiography

      Impaired intraocular blood flow within vascular beds in the human eye is associated with certain ocular diseases including, for example, glaucoma, diabetic retinopathy and age-related macular degeneration. A reliable method to quantify blood flow in the various intraocular vascular beds could provide insight into the vascular component of ocular disease pathophysiology. Using ultrahigh-speed optical coherence tomography (OCT), a new 3D angiography algorithm called split-spectrum amplitude-decorrelation angiography (SSADA) was developed for imaging microcirculation within different intraocular regions. A method to quantify SSADA results was developed and used to detect perfusion changes in early stage ocular disease. Associated embodiments relating to methods ...

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    3. 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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    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. High dynamic range optical coherence tomography angiography (HDR-OCTA)

      High dynamic range optical coherence tomography angiography (HDR-OCTA)

      The dynamic range of current optical coherence tomography (OCT) angiography (OCTA) images is limited by the fixed scanning intervals. High speed OCT devices introduce the possibility of extending the flow signal dynamic range. In this study, we created a novel scanning pattern for achieving high dynamic range (HDR)-OCTA with a superior scanning efficiency. We implemented a bidirectional, interleaved scanning pattern that is sensitive to different flow speeds by adjustable adjacent inter-scan time intervals. We found that an improved flow dynamic range can be achieved by generating 3 different B-scan time intervals using 3 repetitions.

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    9. Systems and methods to compensate for reflectance variation in OCT angiography

      Systems and methods to compensate for reflectance variation in OCT angiography

      Methods and systems for improving quantification of OCT angiography data are disclosed. The disclosure specifically relates to methods for compensating for the effect of tissue reflectance to improve the accuracy and repeatability of OCT angiography measurements. These improvements are effected by deriving and then utilizing a dynamic thresholding approach to process decorrelation data to properly classify flow versus non-flow data in OCT angiograms. The disclosed methods overcome quantification errors associated with within-scan variations in reflectance as well as repeatability problems associated with differences in scan quality over successive imaging sessions.

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    10. 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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    11. 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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    12. 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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    13. Systems and methods for automated segmentation of retinal fluid in optical coherence tomography

      Systems and methods for automated segmentation of retinal fluid in optical coherence tomography

      Disclosed herein are methods and systems for the identification and characterization of fluid accumulation in the retina using OCT imaging. The disclosed methods and systems are directed to the automated segmentation of retinal fluid using 2D or 3D structural OCT scan images. Approaches for visualization and quantification of both intraretinal and subretinal fluid are presented. Methods are also disclosed for using OCT angiography data to improve the quality of retinal fluid segmentation, and to provide combined visualization of fluid accumulation and retinal vasculature to inform clinical interpretation of results.

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    14. 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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    15. 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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    16. 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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    17. 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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    18. Automated phase unwrapping in Doppler optical coherence tomography

      Automated phase unwrapping in Doppler optical coherence tomography

      Phase wrapping is a crucial issue in Doppler optical coherence tomography (OCT) and restricts its automatic implementation for clinical applications that quantify total retinal blood flow. We propose an automated phase-unwrapping technique that takes advantage of the parabolic profile of blood flow velocity in vessels. Instead of inspecting the phase shift manually, the algorithm calculates the gradient magnitude of the phase shift on the cross-sectional image and automatically detects the presence of phase wrapping. The voxels affected by phase wrapping are corrected according to the determined flow direction adjacent to the vessel walls. We validated this technique in the rodent ...

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    19. 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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    20. 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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    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. Systems And Methods For REFLECTANCE-BASED PROJECTION-RESOLVED Optical Coherence Tomography Angiography

      Systems And Methods For REFLECTANCE-BASED PROJECTION-RESOLVED Optical Coherence Tomography Angiography

      Embodiments provide systems and methods associated with a reflectance-based projection-resolved (rbPR) optical coherence tomography angiography (OCTA) algorithm which uses optical coherence tomography (OCT) reflectance to enhance the flow signal and suppress the projection artifacts in 3-dimensional OCTA. rbPR improves the vascular connectivity and improved the discrimination of the deeper plexus angiograms in healthy eyes, compared to prior PR-OCTA method. Additionally, rbPR removes flow projection artifacts more completely from the outer retinal slab in the eyes with age-related macular degeneration, and preserves vascular integrity of the intermediate and deep capillary plexuses in the eyes with diabetic retinopathy. Additionally, the rbPR method ...

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