1. Articles from Christopher Bowd

    1-24 of 27 1 2 »
    1. Diagnostic accuracy of macular thickness map and texture en-face images for detecting glaucoma in eyes with axial high myopia

      Diagnostic accuracy of macular thickness map and texture en-face images for detecting glaucoma in eyes with axial high myopia

      To evaluate the diagnostic accuracy of a novel optical coherence tomography (OCT) texture-based en-face image analysis, called SALSA-Texture, that requires segmentation of only one retinal layer for glaucoma detection in eyes with axial high myopia, and to compare to standard macular ganglion cell-inner plexiform layer (GCIPL) thickness, macular retinal nerve fiber layer (mRNFL) thickness, and ganglion cell complex (GCC) thickness maps.

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      Mentions: UCSD
    2. OCT Angiography Face Mask-associated Artifacts During the COVID-19 Pandemic

      OCT Angiography Face Mask-associated Artifacts During the COVID-19 Pandemic

      Prcis: Face mask wearing has no significant effects on artifacts or vessel density measurements in optic nerve head and macular OCT-Angiography scans. Purpose: To assess the difference in area of artifacts observed in optical coherence tomography angiography (OCT-A) scans with and without face mask wear and to verify if mask wear interferes with OCT-A vessel density measurements. Subjects and controls: 64 eyes of 10 healthy subjects, 4 ocular hypertensive, 8 glaucoma suspects, and 17 glaucoma patients were included. Methods: High density optic nerve head (ONH) and macula OCT-A scans were obtained in patients with and without surgical masks. Seven different ...

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      Mentions: UCSD
    3. Deep learning image analysis of optical coherence tomography angiography measured vessel density improves classification of healthy and glaucoma eyes

      Deep learning image analysis of optical coherence tomography angiography measured vessel density improves classification of healthy and glaucoma eyes

      Purpose : To compare convolutional neural network (CNN) analysis of en face vessel density images to gradient boosting classifier (GBC) analysis of instrument provided, feature-based optical coherence tomography angiography (OCTA) vessel density measurements and OCT RNFL thickness measurements for classifying healthy and glaucomatous eyes. Design : Comparison of diagnostic approaches Methods : 130 eyes of 80 healthy individuals and 275 eyes of 185 glaucoma patients with optic nerve head (ONH) OCTA and OCT imaging were included. Classification performance of a VGG16 CNN trained and tested on entire en face 4.5 mm x 4.5 mm radial peripapillary capillary OCTA ONH images was ...

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      Mentions: UCSD
    4. Individualized Glaucoma Change Detection Using Deep Learning Auto Encoder-Based Regions of Interest

      Individualized Glaucoma Change Detection Using Deep Learning Auto Encoder-Based Regions of Interest

      Purpose : To compare change over time in eye-specific optical coherence tomography (OCT) retinal nerve fiber layer (RNFL)-based region-of-interest (ROI) maps developed using unsupervised deep-learning auto-encoders (DL-AE) to circumpapillary RNFL (cpRNFL) thickness for the detection of glaucomatous progression. Methods : Forty-four progressing glaucoma eyes (by stereophotograph assessment), 189 nonprogressing glaucoma eyes (by stereophotograph assessment), and 109 healthy eyes were followed for ≥3 years with ≥4 visits using OCT. The San Diego Automated Layer Segmentation Algorithm was used to automatically segment the RNFL layer from raw three-dimensional OCT images. For each longitudinal series, DL-AEs were used to generate individualized eye-based ROI maps ...

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      Mentions: UCSD
    5. Long-Term Reproducibility of Optical Coherence Tomography Angiography in Stable Glaucomatous Eyes

      Long-Term Reproducibility of Optical Coherence Tomography Angiography in Stable Glaucomatous Eyes

      Purpose : To assess and compare long-term reproducibility of optical coherence tomography angiography (OCTA) vascular parameters and spectral-domain optical coherence tomography (OCT) thickness parameters in stable glaucoma, glaucoma suspect, and healthy eyes. Methods : A total of 88 eyes (15 healthy, 38 glaucoma suspect, and 35 non-progressive POAG) of 68 subjects were enrolled who had at least 3 visits within 1 to 1.5 years and both OCT and OCTA (Optovue Inc, Fremont, California, USA) imaging on the same day. A series of vascular and thickness parameters were measured including macula whole image vessel density (wiVD), optic nerve head (ONH) circumpapillary capillary ...

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    6. Optical Coherence Tomography Angiography Artifacts in Glaucoma

      Optical Coherence Tomography Angiography Artifacts in Glaucoma

      Purpose: To determine the prevalence of different types of artifacts seen in optical coherence tomography angiography (OCTA) images of healthy and glaucoma eyes and to evaluate the characteristics associated with the increased likelihood of obtaining poor quality images. Design: Retrospective study. Participants: A total of 649 eyes of 368 healthy, glaucoma suspect, and glaucoma patients. Methods: Angiovue high density (HD) and non-HD optic nerve head and macula OCTA images of participants were evaluated by 4 expert reviewers for the presence of different artifacts including eye movement, defocus, shadow, decentration, segmentation error, blink and Z offset in the superficial vascular layer ...

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      Mentions: UCSD
    7. Impact of Pupil Dilation on Optical Coherence Tomography Angiography Retinal Microvasculature in Healthy Eyes

      Impact of Pupil Dilation on Optical Coherence Tomography Angiography Retinal Microvasculature in Healthy Eyes

      Précis: Small but significant decreases in OCTA-measured circumpapillary capillary density were observed in healthy eyes dilated with 2.5% phenylephrine/0.5% tropicamide. Though likely clinically insignificant, ophthalmologists should consider these changes when interpreting OCTA results from dilated eyes. Purpose: To investigate the effect of pupil dilation using 2.5% phenylephrine and 0.5% tropicamide on quantitative assessment of retinal microvasculature using OCTA. Methods: OptoVue AngioVue high density (HD) and non-HD OCTA macula and optic nerve head (ONH) images were obtained at 15-minute intervals pre- and post- dilation in 26 healthy participants (mean age: 40.0; 95% CI=33 ...

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      Mentions: Visionix UCSD
    8. Capillary Density Measured by OCT Angiography in Glaucomatous Optic Disc Phenotypes

      Capillary Density Measured by OCT Angiography in Glaucomatous Optic Disc Phenotypes

      Purpose To compare optical coherence tomography angiography (OCTA) measured capillary density of the optic disc among four glaucomatous optic disc phenotypes. Design Cross-sectional study. Methods Circumpapillary capillary density (cpCD) of four glaucomatous optic disc phenotypes in 193 eyes of 141 glaucoma patients and cpCD in 92 eyes of 55 healthy subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared. Areas under the receiver operating characteristic curves (AUROC) were used to evaluate diagnostic accuracy among groups after adjusting for confounders. Results Four glaucoma phenotypes were assessed including focal ischemic (n=45), generalized cup enlargement (n=60), myopic glaucoma (n ...

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      Mentions: UCSD
    9. Gradient Bosting Classifiers Combining Vessel Density and Tissue Thickness Measurements for Classifying Early to Moderate Glaucoma

      Gradient Bosting Classifiers Combining Vessel Density and Tissue Thickness Measurements for Classifying Early to Moderate Glaucoma

      Purpose To compare gradient boosting classifier (GBC) analysis of optical coherence tomography angiography (OCTA)-measured vessel density (VD) and OCT-measured tissue thickness to standard OCTA VD and OCT thickness parameters for classifying healthy eyes and eyes with early to moderate glaucoma. Design Comparison of diagnostic tools. Methods One-hundred-eight healthy eyes and 193 glaucomatous eyes with OCTA and OCT imaging of the macula and optic nerve head (ONH) were studied. Four GBCs were evaluated that combined 1) all macula VD and thickness measurements (Macula GBC), 2) all ONH VD and thickness measurements (ONH GBC), 3) all VD measurements from the macula ...

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      Mentions: UCSD
    10. Diagnostic Ability of Optical Coherence Tomography Angiography Macula Vessel Density for the Diagnosis of Glaucoma Using Difference Scan Sizes

      Diagnostic Ability of Optical Coherence Tomography Angiography Macula Vessel Density for the Diagnosis of Glaucoma Using Difference Scan Sizes

      Précis: There is diagnostic information in the outer region of OCTA macula scans not available in the inner region, and this information is especially useful in the early stages of glaucoma . Purpose: To evaluate the diagnostic accuracy of 3×3▒mm 2 and 6×6▒mm 2 macula OCT-A scans for classifying healthy, mild glaucoma , and moderate to severe glaucoma eyes. Methods: Participants enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) with good quality 3×3▒mm 2 and 6×6▒mm 2 OCT-A images of the macula (AngioVue; Optovue, Freemont, CA) acquired on the same day were ...

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    11. Deep Learning Approaches Predict Glaucomatous Visual Field Damage from Optical Coherence Tomography Optic Nerve Head Enface Images and Retinal Nerve Fiber Layer Thickness Maps

      Deep Learning Approaches Predict Glaucomatous Visual Field Damage from Optical Coherence Tomography Optic Nerve Head Enface Images and Retinal Nerve Fiber Layer Thickness Maps

      Purpose To develop and evaluate a deep learning system for differentiating between eyes with and without glaucomatous visual field damage (GVFD) and predicting the severity of GFVD from spectral domain optical coherence tomography (SDOCT) optic nerve head images. Design Evaluation of a diagnostic technology Participants 9,765 visual field (VF)–SDOCT pairs collected from 1,194 participants with and without GVFD (1909 eyes). Methods Deep learning models were trained to use SDOCT retinal nerve fiber layer (RNFL) thickness maps, RNFL enface images, and confocal scanning laser ophthalmoscopy (CSLO) images to identify eyes with GVFD and predict quantitative VF mean deviation ...

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    12. Association of Macular and Circumpapillary Microvasculature with Visual Field Sensitivity in Advanced Glaucoma

      Association of Macular and Circumpapillary Microvasculature with Visual Field Sensitivity in Advanced Glaucoma

      Purpose To evaluate the association between optical coherence tomography angiography (OCTA) macular and circumpapillary vessel density and visual field mean deviation (MD) in advanced primary open angle glaucoma (POAG). Design Cross-sectional study. Methods Macula (superficial layer) and optic nerve head [ONH, with (capillary density :CD) and without (vessel density: VD) automated removal of large vessels] OCTA of 34 eyes (34 patients, MD < -10 dB) were investigated as macula whole image VD (wiVD), parafoveal VD (pfVD), ONH wiVD, wiCD, circumpapillary VD (cpVD), and cpCD. Spectral domain OCT circumpapillary retinal nerve fiber layer (cpRNFL), macular ganglion cell complex (GCC) and ganglion cell ...

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      Mentions: UCSD
    13. Measurement floors and dynamic ranges of optical coherence tomography and angiography in glaucoma

      Measurement floors and dynamic ranges of optical coherence tomography and angiography in glaucoma

      Purpose To determine if optical coherence tomography angiography (OCTA)–derived vessel density measurements can extend the available dynamic range for detecting glaucoma compared to spectral-domain optical coherence tomography (SDOCT)–derived thickness measurements. Design Observational, cross-sectional study. Participants A total of 509 eyes from 38 healthy participants, 63 glaucoma suspects and 193 glaucoma patients enrolled in the Diagnostic Innovations in Glaucoma Study. Methods Relative vessel density and tissue thickness measurement floors of perifoveal superficial vessel density (pfVD), circumpapillary capillary density (cpCD), circumpapillary retinal nerve fiber (cpRNFL) thickness, ganglion cell complex (GCC) thickness and visual field mean deviation were investigated and compared ...

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      Mentions: UCSD
    14. Retinal Nerve Fiber Layer Features Identified by Unsupervised Machine Learning on Optical Coherence Tomography Scans Predict Glaucoma Progression

      Retinal Nerve Fiber Layer Features Identified by Unsupervised Machine Learning on Optical Coherence Tomography Scans Predict Glaucoma Progression

      Purpose : To apply computational techniques to wide-angle swept-source optical coherence tomography (SS-OCT) images to identify novel, glaucoma-related structural features and improve detection of glaucoma and prediction of future glaucomatous progression. Methods : Wide-angle SS-OCT, OCT circumpapillary retinal nerve fiber layer (cpRNFL) circle scans spectral-domain (SD)-OCT, standard automated perimetry (SAP), and frequency doubling technology (FDT) visual field tests were completed every 3 months for 2 years from a cohort of 28 healthy participants (56 eyes) and 93 glaucoma participants (179 eyes). RNFL thickness maps were extracted from segmented SS-OCT images and an unsupervised machine learning approach based on principal component analysis ...

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      Mentions: UCSD
    15. Comparing optical coherence tomography radial and cube scan patterns for measuring Bruch's membrane opening minimum rim width (BMO-MRW) in glaucoma and healthy eyes: cross-sectional and longitudinal analysis

      Comparing optical coherence tomography radial and cube scan patterns for measuring Bruch's membrane opening minimum rim width (BMO-MRW) in glaucoma and healthy eyes: cross-sectional and longitudinal analysis

      Aim To compare the cube and radial scan patterns of the spectral domain optical coherence tomography (SD-OCT) for quantifying the Bruch's membrane opening minimum rim width (BMO-MRW). Methods Sixty healthy eyes and 189 glaucomatous eyes were included. The optic nerve head cube and radial pattern scans were acquired using Spectralis SD-OCT. BMO-MRWs were automatically delineated using the San Diego Automated Layer Segmentation Algorithm. The BMO-MRW diagnostic accuracy for glaucoma detection and rates of change derived from the two scan patterns were compared. Results There was a significant difference between the baseline global BMO-MRW measurements of cube and radial scans ...

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      Mentions: UCSD
    16. Estimating OCT Structural Measurement Floors to Improve Detection of Progression In Advanced Glaucoma

      Estimating OCT Structural Measurement Floors to Improve Detection of Progression In Advanced Glaucoma

      Purpose “Floor effects” in retinal imaging are defined as the points at which no further structural loss can be detected. We estimated the measurement floors for spectral-domain optical coherence tomography (SD-OCT) measurements and compared global change over time in advanced glaucoma eyes. Design Validity study to investigate measurement floors. Methods A longitudinal “Variability Group” of 41 eyes with moderate to advanced glaucoma (SAP MD ≤ -8 dB) was used to estimate measurement floors. Minimum rim width (MRW), ganglion cell-inner plexiform layer thickness (GC-IPLT) and circumpapillary retinal nerve fiber layer thickness (cpRNFLT) were determined. Floors were defined as the average image area ...

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      Mentions: UCSD
    17. A hierarchical framework for estimating neuroretinal rim area using 3D spectral domain optical coherence tomography (SD-OCT) optic nerve head (ONH) images of healthy and glaucoma eyes

      A hierarchical framework for estimating neuroretinal rim area using 3D spectral domain optical coherence tomography (SD-OCT) optic nerve head (ONH) images of healthy and glaucoma eyes

      Glaucoma is a chronic neurodegenerative disease characterized by loss of retinal ganglion cells, resulting in distinctive changes in the optic nerve head (ONH) and retinal nerve fiber layer (RNFL). Important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, a crucial step in diagnosing and monitoring glaucoma. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy subjects. In this paper, we present a new approach for locating the Bruch’s membrane opening BMO and then estimating ...

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    18. A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

      A joint estimation detection of Glaucoma progression in 3D spectral domain optical coherence tomography optic nerve head images

      Glaucoma is an ocular disease characterized by distinctive changes in the optic nerve head (ONH) and visual field. Glaucoma can strike without symptoms and causes blindness if it remains without treatment. Therefore, early disease detection is important so that treatment can be initiated and blindness prevented. In this context, important advances in technology for non-invasive imaging of the eye have been made providing quantitative tools to measure structural changes in ONH topography, an essential element for glaucoma detection and monitoring. 3D spectral domain optical coherence tomography (SD-OCT), an optical imaging technique, has been commonly used to discriminate glaucomatous from healthy ...

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      Mentions: UCSD
    19. Agreement Among Spectral-Domain Optical Coherence Tomography Instruments for Assessing Retinal Nerve Fiber Layer Thickness

      Agreement Among Spectral-Domain Optical Coherence Tomography Instruments for Assessing Retinal Nerve Fiber Layer Thickness

      Purpose:: To assess the agreement of parapapillary retinal nerve fiber layer (RNFL) thickness measurements among 3 spectral-domain optical coherence tomography (SD-OCT) instruments.Design:: Observational, cross-sectional study.Methods:: Three hundred thirty eyes (88 with glaucoma, 206 glaucoma suspects, 36 healthy) from 208 individuals enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) were imaged using RTVue, Spectralis and Cirrus in a single visit. Agreement among RNFL thickness measurements was assessed using Bland-Altman plots. The influence of age, axial length, disc size, race, spherical equivalent, and disease severity on the pairwise agreements between different instruments was assessed by regression analysis.Results:: Although ...

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    20. Detection of Glaucoma Progression with Stratus OCT Retinal Nerve Fiber Layer, Optic Nerve Head, and Macular Thickness Measurements

      Purpose. To evaluate and compare the ability of optical coherence tomography (OCT) retinal nerve fiber layer (RNFL), optic nerve head, and macular thickness parameters to detect progressive structural damage in glaucoma. Methods. This observational cohort study included 253 eyes of 253 patients. Images were obtained annually with the Stratus OCT (Carl Zeiss Meditec, Inc., Dublin, CA) along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 4.01 years. Progression was determined by the Guided Progression Analysis software for SAP (Carl Zeiss Meditec, Inc.) and by masked assessment of optic disc stereophotographs performed ...
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    21. Detection of Glaucoma Progression using Stratus OCT Retinal Nerve Fiber Layer, Optic Nerve Head and Macular Thickness Measurements

      Purpose: To evaluate and compare the ability of optical coherence tomography (OCT) retinal nerve fiber layer (RNFL), optic nerve head and macular thickness parameters to detect progressive structural damage in glaucoma. Methods: This was an observational cohort study that included 253 eyes of 253 patients. Images were obtained annually with the Stratus OCT, along with optic disc stereophotographs and standard automated perimetry (SAP) visual fields. The median follow-up time was 4.01 years. Progression was determined by the Guided Progression Analysis software for SAP and by masked assessment of optic disc stereophotographs performed by expert graders. Random coefficient models and ...
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    22. Effect of Signal Strength and Improper Alignment on the Variability of Stratus Optical Coherence Tomography Retinal Nerve Fiber Layer Thickness Measurements

      Purpose To evaluate the effect of signal strength and improper scan alignment on retinal nerve fiber layer (RNFL) thickness measurement variability. Design Retrospective, longitudinal clinical study. Methods All eyes of healthy subjects with at least 2 fast RNFL scan sessions were selected from the Diagnostic Innovations in Glaucoma Study. The chronological first scan was considered to be the baseline. Absolute differences in signal strength and RNFL thickness measurements between baseline and subsequent scans were calculated. Regression analysis was conducted to assess whether signal strength and scan shifts along the horizontal (nasal–temporal) but not the vertical (superior–inferior) axis affect ...
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    23. Reproducibility of RTVue Retinal Nerve Fiber Layer Thickness and Optic Disc Measurements and Agreement with Stratus Optical Coherence Tomography Measurements

      Purpose: To evaluate RTVue spectral-domain optical coherence tomography (OCT) (Optovue Inc, Fremont, California, USA) reproducibility and to assess agreement with Stratus time-domain OCT (Carl Zeiss Meditec, Dublin, California, USA) measurements.Design: Observational clinical study.Methods: Scans were obtained from both eyes of all participants 3 times using the RTVue nerve head map 4-mm diameter protocol and once using Stratus OCT within the same session. RTVue reproducibility and agreement with Stratus OCT were evaluated for retinal nerve fiber layer (RNFL) and optic disc measurements.Results: Thirty healthy participants (60 eyes) and 38 glaucoma patients (76 eyes) were included in the study ...
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    24. Spectral domain-optical coherence tomography to detect localized retinal nerve fiber layer defects in glaucomatous eyes

      Spectral domain-optical coherence tomography to detect localized retinal nerve fiber layer defects in glaucomatous eyes
      This study examines the ability of RTVue, Cirrus and Spectralis OCT Spectral domain-optical coherence tomographs (SD-OCT) to detect localized retinal nerve fiber layer defects in glaucomatous eyes. In this observational case series, four glaucoma patients (8 eyes) were selected from the University ... [Opt. Express 17, 4004-4018 (2009)]
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