1. Articles from Zhongdi Chu

    1-24 of 43 1 2 »
    1. Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Non-Glaucoma Eyes

      Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Non-Glaucoma Eyes

      Précis: Peripapillary vessel parameters from optical coherence tomography angiography (OCTA) 4.5×4.5 mm scans in nonglaucomatous and glaucomatous eyes showed high repeatability and reproducibility, with higher reliability for commercially developed OCTA parameters compared with custom OCTA parameters. Purpose: The purpose of this study was to assess intrasession repeatability versus intersession reproducibility of peripapillary vessel parameters from 4.5×4.5 mm OCTA scans in nonglaucomatous eyes and glaucomatous eyes. Materials and Methods: In a longitudinal study, peripapillary OCTA scans were quantified using research-oriented custom quantification software that calculated vessel area density (VAD) and flux and clinic-oriented commercially ...

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    2. A deep learning model for automated segmentation of geographic atrophy imaged with swept-source optical coherence tomography images

      A deep learning model for automated segmentation of geographic atrophy imaged with swept-source optical coherence tomography images

      Purpose: To present a deep-learning algorithm for the segmentation of geographic atrophy (GA) using en face swept-source optical coherence tomography (SS-OCT) images that is accurate and reproducible for the assessment of GA growth over time. Design: Retrospective review of images obtained as part of a prospective natural history study Subjects: Patients with GA (90), early/intermediate AMD (32), healthy controls (16) METHODS: An automated algorithm utilizing scan volume data to generate three image inputs characterizing the main OCT features of GA - hyper-transmission in sub RPE slab, regions of RPE loss, and loss of retinal thickness - was trained with 126 images ...

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    3. Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Nonglaucoma Eyes

      Repeatability and Reproducibility of 4.5 by 4.5 mm Peripapillary Optical Coherence Tomography Angiography Scans in Glaucoma and Nonglaucoma Eyes

      Prcis: Peripapillary vessel parameters from optical coherence tomography angiography (OCTA) 4.5×4.5 mm scans in nonglaucomatous and glaucomatous eyes showed high repeatability and reproducibility, with higher reliability for commercially developed OCTA parameters compared with custom OCTA parameters. Purpose: The purpose of this study was to assess intrasession repeatability versus intersession reproducibility of peripapillary vessel parameters from 4.5×4.5 mm OCTA scans in nonglaucomatous eyes and glaucomatous eyes. Materials and methods: In a longitudinal study, peripapillary OCTA scans were quantified using research-oriented custom quantification software that calculated vessel area density (VAD) and flux and clinic-oriented commercially developed ...

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    4. Swept-Source Optical Coherence Tomography Detection of Bruch’s Membrane and Choriocapillaris Abnormalities in Sorsby Macular Dystrophy

      Swept-Source Optical Coherence Tomography Detection of Bruch’s Membrane and Choriocapillaris Abnormalities in Sorsby Macular Dystrophy

      Purpose: Swept-source optical coherence tomography angiography (SS-OCTA) was used to analyze Bruch's membrane (BM) and choriocapillaris (CC) abnormalities in undiagnosed family members with Sorsby macular dystrophy (SMD). Methods: In a family with SMD (TIMP3 Tyr191Cys), SS-OCTA imaging was performed using the 6X6mm scan patter and previously validated algorithms to detect abnormalities in BM and the CC, as well as the presence of reticular pseudodrusen (RPD) and macular neovascularization (MNV). Genetic analyses were performed for TIMP3 mutations. Results: Of eight family members, two were previously diagnosed with SMD and six were asymptomatic. SS-OCTA imaging of the 33-year-old proband revealed type ...

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    5. Automatic geographic atrophy segmentation using optical attenuation in OCT scans with deep learning

      Automatic geographic atrophy segmentation using optical attenuation in OCT scans with deep learning

      A deep learning algorithm was developed to automatically identify, segment, and quantify geographic atrophy (GA) based on optical attenuation coefficients (OACs) calculated from optical coherence tomography (OCT) datasets. Normal eyes and eyes with GA secondary to age-related macular degeneration were imaged with swept-source OCT using 6 × 6 mm scanning patterns. OACs calculated from OCT scans were used to generate customized composite en face OAC images. GA lesions were identified and measured using customized en face sub-retinal pigment epithelium (subRPE) OCT images. Two deep learning models with the same U-Net architecture were trained using OAC images and subRPE OCT images. Model ...

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    6. Intrasession Repeatability and Intersession Reproducibility of Macular Vessel Parameters on Optical Coherence Tomography Angiography in Glaucomatous and Non-Glaucomatous Eyes

      Intrasession Repeatability and Intersession Reproducibility of Macular Vessel Parameters on Optical Coherence Tomography Angiography in Glaucomatous and Non-Glaucomatous Eyes

      Purpose: Using optical coherence tomography angiography (OCTA), this study compared intrasession repeatability versus intersession reproducibility of macular vessel parameters in glaucoma and non-glaucoma subjects. Methods: 6x6 mm 2 macular OCTA scans (Cirrus HD-OCT 5000) were acquired from glaucomatous and non-glaucomatous subjects as part of an observational, longitudinal study. Vessel area density (VAD) and vessel skeleton density (VSD) were calculated using research-based quantification software while perfusion density (PD Z ) and vessel density (VD Z ) were calculated using commercially developed software (Cirrus 11.0, Carl Zeiss Meditec). Intrasession repeatability and intersession reproducibility were determined using within-eye standard deviation (S W ), within-eye coefficient ...

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    7. Capillary density and caliber as assessed by optical coherence tomography angiography may be significant predictors of diabetic retinopathy severity

      Capillary density and caliber as assessed by optical coherence tomography angiography may be significant predictors of diabetic retinopathy severity

      Purpose To validate retinal capillary density and caliber associations with diabetic retinopathy (DR) severity in different clinical settings. Methods This cross-sectional study assessed retinal capillary density and caliber in the superficial retinal layer of 3-mm OCTA scans centered on the fovea. Images were collected from non-diabetic controls and subjects with mild or referable DR (defined DR worse than mild DR) between February 2016 and December 2019 at secondary and tertiary eye care centers. Vessel Skeleton Density (VSD), a measure of capillary density, and Vessel Diameter Index (VDI), a measure of vascular caliber, were calculated from these images. Discriminatory performance of ...

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    8. Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits

      Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits

      The purpose of this study is to quantitatively assess correlations between local geographic atrophy (GA) growth rates and local optical coherence tomography angiography (OCTA)-measured choriocapillaris (CC) flow deficits. Thirty-eight eyes from 27 patients with GA secondary to age-related macular degeneration (AMD) were imaged with a commercial 1050 nm swept-source OCTA instrument at 3 visits, each separated by ∼6 months. Pearson correlations were computed between local GA growth rates, estimated using a biophysical GA growth model, and local OCTA CC flow deficit percentages measured along the GA margins of the baseline visits. The p-values associated with the null hypothesis of ...

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    9. Optical Coherence Tomography Angiography-Derived Flux As a Measure of Physiological Changes in Retinal Capillary Blood Flow

      Optical Coherence Tomography Angiography-Derived Flux As a Measure of Physiological Changes in Retinal Capillary Blood Flow

      Purpose: To compare optical coherence tomography angiography (OCTA)-derived flux with conventional OCTA measures of retinal vascular density in assessment of physiological changes in retinal blood flow. Methods: Healthy subjects were recruited, and 3 × 3-mm2 fovea-centered scans were acquired using commercially available swept-source OCTA (SS-OCTA) while participants were breathing room air, 100% O2, or 5% CO2. Retinal perfusion was quantified using vessel area density (VAD) and vessel skeleton density (VSD), as well as novel measures of retinal perfusion, vessel area flux (VAF) and vessel skeleton flux (VSF). Flux is proportional to the number of red blood cells moving through a ...

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    10. Steps to Measurement Floor of an Optical Microangiography Device in Glaucoma

      Steps to Measurement Floor of an Optical Microangiography Device in Glaucoma

      Purpose To compare dynamic ranges and steps to measurement floors of peripapillary and macular metrics from a complex signal-based optical microangiography (OMAG C ) optical coherence tomography angiography (OCTA) device for glaucoma with those of OCT measurements. Design Cross-sectional study. Methods Imaging of 252 eyes from 173 glaucoma subjects and 123 eyes from 92 non-glaucoma subjects from a glaucoma clinic was quantified using custom and commercial software. Metrics from OCT (retinal nerve fiber layer [RNFL], ganglion cell-inner plexiform layer [GCIPL]) and OCTA (custom: peripapillary vessel area density [pVAD], macular vessel area density [mVAD], macular vessel skeleton density [mVSD]; commercial: peripapillary perfusion ...

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    11. Swept-Source OCT Angiographic Characteristics of Treatment-Naïve Nonexudative Macular Neovascularization in AMD Prior to Exudation

      Swept-Source OCT Angiographic Characteristics of Treatment-Naïve Nonexudative Macular Neovascularization in AMD Prior to Exudation

      Purpose: To investigate the characteristics of treatment-naïve nonexudative macular neovascularization (MNV) in age-related macular degeneration before the onset of exudation using swept-source optical coherence tomography angiography. Methods: MNV area, choriocapillaris (CC) flow deficits (FDs), vessel area density (VAD), vessel skeleton density (VSD), retinal pigment epithelial detachment (PED) volume, mean choroidal thickness (MCT), and choroid vascularity index (CVI) measurements were assessed at two visits prior to exudation. We compared measurements made at the second visit and the rate of change between visits in eyes with and without exudation. The differences in these parameters between eyes with and without subsequent exudation ...

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    12. Robust three-dimensional registration on optical coherence tomography angiography for speckle reduction and visualization

      Robust three-dimensional registration on optical coherence tomography angiography for speckle reduction and visualization

      Background: In the clinical applications of optical coherence tomography angiography (OCTA), the repeated scanning and averaging method can provide better contrast with reduced speckle noises in the final results, which are useful for visualizing and quantifying vascular components with high accuracy, reproducibility, and reliability. However, the inevitable patient motion presents a challenge to this method. The objective of this study is to meet this challenge by introducing a 3D registration method to register optical coherence tomography (OCT)/OCTA scans for precise volume averaging of multiple scans to improve the signal-to-noise ratio (SNR) and increase quantification accuracy. Methods: The proposed method ...

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    13. Swept source OCTA reveals a link between choriocapillaris blood flow and vision loss in a case of tubercular serpiginous-like choroiditis

      Swept source OCTA reveals a link between choriocapillaris blood flow and vision loss in a case of tubercular serpiginous-like choroiditis

      Optical coherence tomography angiography (OCTA) is a non-invasive technique that is useful in the diagnosis and management of patients with posterior uveitis. Here we report the use of swept source OCTA (SS-OCTA) in a patient with tuberculosis (TB) associated serpiginous like choroiditis (TB-SLC) that made a full visual recovery following treatment with ATT, local and systemic corticosteroids, and systemic immune modulation. By comparing en face images of choriocapillaris (CC) blood flow before and after treatment, we conclude that the patient's visual recovery was associated with resolution of extensive CC flow deficits. This case highlights the utility of SS-OCTA in ...

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    14. Correlations Between Choriocapillaris and Choroidal Measurements and the Growth of Geographic Atrophy using Swept Source OCT Imaging

      Correlations Between Choriocapillaris and Choroidal Measurements and the Growth of Geographic Atrophy using Swept Source OCT Imaging

      Purpose The correlations between enlargement rates (ERs) of geographic atrophy (GA) and choriocapillaris (CC) flow deficits (FDs), mean choroidal thickness (MCT), and choroidal vascularity index (CVI) were investigated using swept source optical coherence tomography (SS-OCT) in age-related macular degeneration (AMD). Design Retrospective review of prospective, observational case series. Methods Eyes with GA from AMD were imaged with SS-OCT (PLEX® Elite 9000; Carl Zeiss Meditec, Inc, Dublin, CA) using 6x6 mm scan pattern. GA lesions were identified and measured using custom en face structural images and annual square root ERs of GA were calculated. At baseline, CC FDs from different regions ...

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    15. Quantitative assessment of choriocapillaris flow deficits in diabetic retinopathy: A swept-source optical coherence tomography angiography study

      Quantitative assessment of choriocapillaris flow deficits in diabetic retinopathy: A swept-source optical coherence tomography angiography study

      Purpose To quantitatively assess choriocapillaris (CC) flow deficits in eyes with diabetic retinopathy (DR) using swept-source optical coherence tomography angiography (SS-OCTA). Methods Diabetic subjects with different stages of DR and age-matched healthy subjects were recruited and imaged with SS-OCTA. The en face CC blood flow images were generated using previously published and validated algorithms. The percentage of CC flow deficits (FD%) and the mean CC flow deficit size were calculated in a 5-mm-diameter circle centered on the fovea from the 6×6-mm scans. Results Forty-five diabetic subjects and 27 control subjects were included in the study. The CC FD% in ...

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    16. Macular microvascular parameters in the ganglion cell-inner plexiform layer derived by optical coherence tomography angiography: Vascular structure-central visual function analysis

      Macular microvascular parameters in the ganglion cell-inner plexiform layer derived by optical coherence tomography angiography: Vascular structure-central visual function analysis

      Purpose To investigate the relationships between global and sectoral macular vascular microcirculation parameters in the ganglion cell-inner plexiform layer (GCIPL) assessed by optical coherence tomography angiography (OCTA), and global and sectoral visual field (VF) central mean sensitivity (CMS) assessed by standard automated perimetry. Methods Fifty-four eyes with open angle glaucoma were scanned using a swept-source OCTA (Plex Elite 9000, Zeiss, Dublin, CA) and macular vascular microcirculation was measured by calculating the overall flux and vessel area density (VAD) over the entire 6mm x 6mm area, excluding large retinal vessels. Central 10-degree VF CMS was calculated based on 24–2 VF ...

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    17. Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain–Optical Coherence Tomography Angiography

      Quantifying Subclinical and Longitudinal Microvascular Changes Following Episcleral Plaque Brachytherapy Using Spectral Domain–Optical Coherence Tomography Angiography

      Purpose: This work assesses longitudinal microvascular changes in eyes treated with iodine-125 episcleral plaque brachytherapy (EPB). Methods: High-resolution optical coherence tomography angiograms (OCTAs) of the central 3 × 3-mm macula were obtained from iodine-125 EPB–treated and untreated fellow eyes of 61 patients. Previously validated semiautomated algorithms quantified capillary density (vessel skeleton density [VSD]) and caliber (vessel diameter index). Nonperfusion was also quantified as flow impairment region (FIR). Examinations from treated and fellow eyes obtained before treatment and at 6-month, 1-year, and 2-year intervals were compared using generalized estimating equation linear models. Dosimetry maps evaluated spatial correlation between radiation dose and ...

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    18. Impacts of Axial Length on Retinal and Choriocapillaris Blood Flow Quantification in Myopia with Swept-Source Optical Coherence Tomography Angiography

      Impacts of Axial Length on Retinal and Choriocapillaris Blood Flow Quantification in Myopia with Swept-Source Optical Coherence Tomography Angiography

      Purpose : To evaluate the impact of image magnification correction on retinal and choriocapillaris (CC) blood flow quantification using swept-source optical coherence tomography angiography (OCTA) in myopic eyes. Methods : Subjects with myopia were recruited for ocular biometry, refraction, and OCTA imaging with a 6 × 6-mm protocol. The retinal vascular area density (RVAD), retinal vascular skeleton density (RVSD), retinal flow impairment area (RFIA), percentage of CC flow deficits (FD%), and the mean size of CC flow deficits (FDs) were quantified within a 5-mm-diameter circle centered on the fovea before and after magnification correction using the Littman and the modified Bennett formulae. Results ...

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    19. Validation of a Compensation Strategy used to Detect Choriocapillaris Flow Deficits Under Drusen with Swept Source OCT Angiography

      Validation of a Compensation Strategy used to Detect Choriocapillaris Flow Deficits Under Drusen with Swept Source OCT Angiography

      Purpose A compensation strategy that was developed to measure the choriocapillaris (CC) flow deficits (FDs) under drusen was tested in eyes with large drusen from age-related macular degeneration (AMD) before and after the drusen spontaneously resolved without evidence of disease progression. Design Prospective, observational consecutive case series. Methods Patients with AMD were enrolled in a prospective SS-OCT imaging study (PLEX® Elite 9000, Carl Zeiss Meditec). Consecutive eyes with large drusen were followed, and eyes that underwent spontaneous collapse of drusen without evidence of disease progression were identified retrospectively. The drusen-resolved regions were manually outlined. CC FDs were measured using a ...

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    20. Clinical Utility of Triplicate En Face Image Averaging for Optical Coherence Tomography Angiography in Glaucoma and Glaucoma Suspects

      Clinical Utility of Triplicate En Face Image Averaging for Optical Coherence Tomography Angiography in Glaucoma and Glaucoma Suspects

      Précis: Averaging triplicate en face angiograms of the radial peripapillary capillary plexus with optical coherence tomography angiography (OCTA) improves vessel visualization, reduces vessel density parameters, and increases the diagnostic accuracy for glaucoma of one such parameter. Purpose: To test the hypothesis that triplicate averaging of the radial peripapillary capillary (RPC) layer improves visualization and diagnostic accuracy of optical coherence tomography angiography (OCTA) for glaucoma . Methods: This is a cross-sectional study involving 63 primary open angle glaucoma patients and 70 age-matched glaucoma suspects. Triplicate 6×6mm OCTA scans of the optic nerve head were acquired, and the RPC layer was ...

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    21. Quantitative Analysis of the Choriocapillaris in Uveitis Using en face Swept Source Optical Coherence Tomography Angiography

      Quantitative Analysis of the Choriocapillaris in Uveitis Using en face Swept Source Optical Coherence Tomography Angiography

      Purpose To perform a quantitative analysis of choriocapillaris (CC) flow deficits (FDs) in patients with uveitis. Design Retrospective cross-sectional study Methods Swept-source optical coherence tomography based angiography (SS-OCTA) macular volume scans (3x3 mm and 6x6 mm) were obtained using the PLEX® Elite 9000: En face CC images were generated and analyzed using an automated flow deficit identification algorithm. Three quantitative metrics were determined for each eye: FD number (FDN), mean FD size (MFDS), and FD density (FDD). Quantitative metrics were compared between uveitis and control eyes. The uveitis cohort was further subdivided by the presence or absence of choroidal involvement ...

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    22. Correlations between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes using Swept Source OCT Angiography

      Correlations between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes using Swept Source OCT Angiography

      Purpose Choriocapillaris (CC) imaging of normal eyes with swept-source optical coherence tomography SS-OCTA was performed, and the percentage of CC flow deficits (FD%) and the average area of CC flow deficits (FDa) were compared within given macular regions. Design A prospective, cross-sectional study. Methods Subjects with normal eyes ranging in age from their 20s through their 80s were imaged with SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec, Dublin, CA) using both 3x3 mm and 6x6 mm macular scan patterns. The CC images were generated using a previously published and validated algorithm. In both 3x3 mm and 6x6 mm scans, the ...

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    23. Quantification of choriocapillaris with OCTA: a comparison study

      Quantification of choriocapillaris with OCTA: a comparison study

      Purpose To demonstrate the variation in quantitative choriocapillaris (CC) metrics with various binarization approaches using optical coherence tomography angiography (OCTA). Design Retrospective, observational, cross-sectional case series. Methods 3x3 mm and 6x6 mm macular OCTA scans were obtained from normal eyes and from eyes with drusen secondary to AMD. The CC slab was extracted and the CC flow deficits (FDs) were segmented with two previously published algorithms: fuzzy C-means approach (FCM method) and Phansalkar’s local thresholding (Phansalkar method). Four different values for the radius were used in order to investigate the effect on the FD segmentation when using the Phansalkar ...

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    24. Systems and methods for quantitative assessment of microvasculature using optical coherence tomography angiography

      Systems and methods for quantitative assessment of microvasculature using optical coherence tomography angiography

      A five-index quantitative analysis of OCT angiograms is disclosed. One method of analyzing an anatomical region of interest of a subject includes acquiring vascular image data from the region of interest and generating a binary vasculature map from the vascular image data. A vessel skeleton map and vessel perimeter map are generated from the binary vasculature map. Based on the three generated maps, a vessel area density, vessel skeleton density, vessel perimeter index, vessel diameter index, and vessel complexity can be determined, in addition to detection of any flow impairment zones in the region of interest. These metrics can be ...

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    1-24 of 43 1 2 »
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