1. Articles from Joong Won Shin

    1-21 of 21
    1. Development of a β-Variational Autoencoder for Disentangled Latent Space Representation of Anterior Segment Optical Coherence Tomography Images

      Development of a β-Variational Autoencoder for Disentangled Latent Space Representation of Anterior Segment Optical Coherence Tomography Images

      Purpose: To investigate the feasibility of extracting a low-dimensional latent structure of anterior segment optical coherence tomography (AS-OCT) images by use of a β-variational autoencoder (β-VAE). Methods: We retrospectively collected 2111 AS-OCT images from 2111 eyes of 1261 participants from the ongoing Asan Glaucoma Progression Study. After hyperparameter optimization, the images were analyzed with β-VAE. Results: The mean participant age was 64.4 years, with mean values of visual field index and mean deviation of 86.4% and -5.33 dB, respectively. After experiments, a latent space size of 6 and β value of 53 were selected for latent space analysis ...

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    2. Clinical characteristics of choroidal microvasculature dropout in normal-tension glaucoma versus nonarteritic anterior ischemic optic neuropathy: an optical coherence tomography angiography study

      Clinical characteristics of choroidal microvasculature dropout in normal-tension glaucoma versus nonarteritic anterior ischemic optic neuropathy: an optical coherence tomography angiography study

      The present study investigated the characteristics of choroidal microvasculature dropout (CMvD) in eyes with nonarteritic anterior ischemic optic neuropathy (NAION) versus those in eyes with normal-tension glaucoma (NTG). This study included 27 NAION, 27 NTG, and 27 healthy control subjects. CMvD was observed in 15 eyes (55.6%) of the NAION group and 20 (74.1%) of the NTG group. The area and angular width of CMvD were significantly greater in eyes with NAION (0.278 ± 0.172 mm 2 and 86.5 ± 42.3°) than in those with NTG (0.138 ± 0.068 mm 2 and 35.1 ± 16 ...

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    3. Glaucoma diagnostic capabilities of macular vessel density on optical coherence tomography angiography: superficial versus deep layers

      Glaucoma diagnostic capabilities of macular vessel density on optical coherence tomography angiography: superficial versus deep layers

      Background/aims: To compare glaucoma diagnostic capabilities of superficial and deep macular vessel density (mVD) parameters in a series of healthy and open-angle glaucoma (OAG) eyes with central visual field (CVF) loss. Methods: We consecutively enrolled 113 eyes of 113 patients with OAG and 47 eyes of 47 healthy participants in a retrospective manner. Superficial and deep mVDs were measured at foveal, parafoveal and perifoveal locations on optical coherence tomography (OCT) angiography. The macular ganglion cell-inner plexiform layer thickness (mGCIPLT) was measured on OCT as a reference standard. Glaucoma diagnostic capabilities of superficial and deep mVD parameters were assessed according ...

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    4. Optical Coherence Tomography Angiography Characteristics and Predictors of Visual Outcomes in Patients with Acute and Chronic Nonarteritic Anterior Ischemic Optic Neuropathy

      Optical Coherence Tomography Angiography Characteristics and Predictors of Visual Outcomes in Patients with Acute and Chronic Nonarteritic Anterior Ischemic Optic Neuropathy

      Background/Aims: To investigate the correlation between optical coherence tomography angiography (OCTA) characteristics and visual outcomes in patients with acute and chronic nonarteritic anterior ischemic optic neuropathy (NAION). Methods: We retrospectively reviewed clinical data and OCTA images of 26 eyes of 26 patients who had been diagnosed with unilateral NAION. OCTA images were acquired from 17 eyes at the acute stage and from 21 eyes at the chronic stage of NAION. We analyzed the peripapillary vessel density (VD) and macular VD in various layers of the retina and choroid for all images. Possible correlations between the OCTA parameters and visual ...

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    5. Peripapillary and Macular Vessel Density Measurement by Optical Coherence Tomography Angiography in Pseudoexfoliation and Primary Open Angle Glaucoma

      Peripapillary and Macular Vessel Density Measurement by Optical Coherence Tomography Angiography in Pseudoexfoliation and Primary Open Angle Glaucoma

      Precis: Pseudoexfoliation glaucoma eyes had a similar level of peripapillary and superficial macular vessel densities compared with primary open-angle glaucoma eyes matched for age and glaucoma severity when assessed by optical coherence tomography angiography. Purpose: To compare vessel density (VD) measured by optical coherence tomography angiography (OCT-A) between primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) in the peripapillary and macular areas. Methods: The circumpapillary (cpVD), parafoveal (pfVD), and perifoveal vessel densities (perifVD) were obtained using OCT-A (AngioVue/RTVue-XR) in 98 eyes from 98 subjects (age, visual acuity (VA), visual field (VF) mean deviation (MD) matched 49 POAG and 49 ...

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    6. Effects of Age on Peripapillary and Macular Vessel Density Determined Using Optical Coherence Tomography Angiography in Healthy Eyes

      Effects of Age on Peripapillary and Macular Vessel Density Determined Using Optical Coherence Tomography Angiography in Healthy Eyes

      Purpose : To evaluate the effect of age on global and sectoral vascular parameters of the peripapillary area and macula in healthy eyes by using optical coherence tomography angiography (OCT-A). Methods : This retrospective cross-sectional study included 239 eyes of 172 healthy subjects. Subjects were scanned using the high-definition disc angio scan (4.5 × 4.5 mm), retina angio scan (6 × 6 mm), and optic nerve head/ganglion cell complex (GCC) modes of OCT-A. Global and sectoral circumpapillary vessel density (VD), parafoveal VD, retinal nerve fiber layer (RNFL), and GCC thickness parameters were modeled in terms of age by using linear mixed-effect ...

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    7. Relationship Between Optical Coherence Tomography Angiography Peripapillary Vessel Density and Lamina Cribrosa Depth

      Relationship Between Optical Coherence Tomography Angiography Peripapillary Vessel Density and Lamina Cribrosa Depth

      Précis: Peripapillary vessel density assessed by optical coherence tomography angiography has poor global and regional correlations with lamina cribrosa depth , except for the inferotemporal area. Purpose: To investigate the global and regional relationship between the peripapillary vessel density (pVD) assessed by optical coherence tomography angiography (OCT-A) and lamina cribrosa depth (LCD) assessed by enhanced depth imaging spectral-domain optical coherence tomography (SD-OCT). Methods: A total of 38 eyes of 38 healthy subjects and 38 eyes of 38 glaucoma patients were included. Peripapillary microvasculature and lamina cribrosa were imaged by OCT-A and enhanced depth imaging SD-OCT, respectively. The pVD and LCD ...

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    8. An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

      An Optical Coherence Tomography Angiography Study of the Relationship Between Foveal Avascular Zone Size and Retinal Vessel Density

      Purpose : To assess the relationship between the size of the foveal avascular zone (FAZ; area and perimeter) and vessel density (VD) at various retinal regions using optical coherence tomography angiography (OCTA) in patients with open-angle glaucoma (OAG). Methods : In this retrospective cross-sectional study, OAG eyes were grouped according to the presence/absence of central visual field (CVF) defects. A control group of normal eyes was also included. OCTA images were obtained from the optic nerve (4.5 × 4.5 mm 2 ) and macular (3 × 3 mm 2 ) area, in which VDs were measured in the circumpapilla, parafovea, and fovea regions ...

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    9. Glaucoma Diagnostic Capabilities of Foveal Avascular Zone Parameters Using Optical Coherence Tomography Angiography According to Visual Field Defect Location

      Glaucoma Diagnostic Capabilities of Foveal Avascular Zone Parameters Using Optical Coherence Tomography Angiography According to Visual Field Defect Location

      Purpose: To assess the diagnostic ability of foveal avascular zone (FAZ) parameters to discriminate glaucomatous eyes with visual field defects (VFDs) in different locations (central vs. peripheral) from normal eyes. Patients and Methods: Totally, 125 participants were separated into three groups: normal (n=45), glaucoma with peripheral VFD (PVFD, n=45), and glaucoma with central VFD (CVFD, n=35). The FAZ area, perimeter, and circularity and parafoveal vessel density were calculated from optical coherence tomography angiography images. The diagnostic ability of the FAZ parameters and other structural parameters was determined according to glaucomatous VFD location. Associations between the FAZ parameters ...

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    10. Quantitative optical coherence tomography angiography of macular vascular structure and foveal avascular zone in glaucoma

      Quantitative optical coherence tomography angiography of macular vascular structure and foveal avascular zone in glaucoma

      Objective The study aimed to evaluate the quantitative characteristics of the macular vessel density (VD) and foveal avascular zone (FAZ) in glaucoma using optical coherence tomography angiography (OCT-A). Design Cross-sectional, age- and sex-matched case–control study. Methods Fifty-two eyes of 52 patients with primary open angle glaucoma and 52 eyes from 52 healthy participants were recruited retrospectively. OCT-A was performed on a 3 x 3-mm macular region centered on the fovea. OCT-A scans were manually graded to define the FAZ. Parafoveal VD in superficial and deep retina were analyzed in the circular- and quadrant-segmented zone. The FAZ parameters included size ...

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    11. Ganglion Cell–Inner Plexiform Layer Change Detected by Optical Coherence Tomography Indicates Progression in Advanced Glaucoma

      Ganglion Cell–Inner Plexiform Layer Change Detected by Optical Coherence Tomography Indicates Progression in Advanced Glaucoma

      Purpose To examine the performance of Guided Progression Analysis (GPA; Carl Zeiss Meditec, Dublin, CA) in spectral-domain optical coherence tomography (OCT) in detecting progressive thinning of ganglion cell–inner plexiform layer (GCIPL) and retinal nerve fiber layer (RNFL) in glaucoma. Design Longitudinal, observational study. Participants A total of 196 eyes of 123 primary open-angle glaucoma patients (mean follow-up, 5.0 years). Methods Macular GCIPL and peripapillary RNFL thicknesses were measured by Cirrus HD-OCT (Zeiss, Dublin, CA), and progressive GCIPL and RNFL thinning were assessed by GPA. The reference standard of glaucoma progression was determined by visual field (VF) progression. Glaucomatous ...

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    12. Optical coherence tomography angiography vessel density mapping at various retinal layers in healthy and normal tension glaucoma eyes

      Optical coherence tomography angiography vessel density mapping at various retinal layers in healthy and normal tension glaucoma eyes

      Purpose To investigate peripapillary vessel density at various spatial locations and layers in healthy and normal tension glaucoma eyes using optical coherence tomography angiography (OCTA). Methods A commercial OCTA device (AngioPlex; Carl Zeiss Meditec) was used to image microvasculature in a 6 × 6-mm optic disc region. Vessel densities of superficial and deep retinal layers were calculated using an automatic thresholding algorithm. Vessel density maps were plotted by averaging individual angiogram images. The spatial characteristics of vessel densities were analyzed at clock-hour sectors and in five 0.7-mm-thick concentric circles from a diameter of 2.0 to 5.5 mm. Areas ...

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    13. Subclassification of Primary Angle Closure Using Anterior Segment Optical Coherence Tomography and Ultrasound Biomicroscopic Parameters

      Subclassification of Primary Angle Closure Using Anterior Segment Optical Coherence Tomography and Ultrasound Biomicroscopic Parameters

      Purpose To classify eyes with primary angle closure (PAC) in terms of the features visualized using anterior segment optical coherence tomography (AS-OCT) and ultrasound biomicroscopy (UBM). Design Retrospective, observational study. Participants A total of 73 eyes of 73 patients with PAC. Methods Participants' eyes that had undergone laser peripheral iridotomy (LPI) were imaged using AS-OCT and UBM under the same lighting conditions. Anterior chamber depth, anterior chamber width, iris cross-sectional area, peripheral iris thickness, iris curvature, lens vault (LV), and angle opening distance 500 μm from the scleral spur (SS) were determined using the AS-OCT image; trabecular-ciliary process angle (TCA ...

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    14. Alterations of the Foveal Avascular Zone Measured by Optical Coherence Tomography Angiography in Glaucoma Patients With Central Visual Field Defects

      Alterations of the Foveal Avascular Zone Measured by Optical Coherence Tomography Angiography in Glaucoma Patients With Central Visual Field Defects

      Purpose : To investigate whether the area and shape of the foveal avascular zone (FAZ) as assessed by optical coherence tomography angiography (OCTA) are altered in glaucomatous eyes with central visual field defects (CVFDs). Methods : A total of 78 patients with open-angle glaucoma with central or peripheral visual field defects (PVFDs) confined to a single hemifield were studied retrospectively. Foveal avascular zone area and circularity were measured using OCTA images from the superficial retinal layer. Central retinal visual field (VF) sensitivity using Swedish Interactive Threshold Algorithm 24-2 VF and macular ganglion cell–inner plexiform layer (mGCIPL) thickness were measured. The FAZ ...

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    15. The Effect of Optic Disc Center Displacement on Retinal Nerve Fiber Layer Measurement Determined by Spectral Domain Optical Coherence Tomography

      The Effect of Optic Disc Center Displacement on Retinal Nerve Fiber Layer Measurement Determined by Spectral Domain Optical Coherence Tomography

      Purpose To investigate the effect of optic disc center displacement on retinal nerve fiber layer (RNFL) measurement determined by spectral domain optical coherence tomography (SD-OCT). Methods The optic disc center was manipulated at 1-pixel intervals in horizontal, vertical, and diagonal directions. According to the manipulated optic disc center location, the RNFL thickness data were resampled: (1) at a 3.46-mm diameter circle; and (2) between a 2.5-mm diameter circle and 5.4-mm square. Error was calculated between the original and resampled RNFL measurements. The tolerable error threshold of the optic disc center displacement was determined by considering test-retest variability ...

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    16. Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomography

      Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomography

      Purpose: To compare the topographic features of localized retinal nerve fiber layer (RNFL) defects presented in red-free RNFL photography and spectral domain optical coherence tomography (SD-OCT), and to evaluate the correlation with structural and functional parameters. Methods: Sixty eyes with localized RNFL defects in red-free RNFL photographs were included. RNFL thickness map and significance map were obtained by SD-OCT. The angular location, angular width, and area of localized RNFL defects were measured and compared among RNFL thickness map, significance map (red, <1% level; yellow, <5% level), and RNFL photograph. The RNFL defect areas were analyzed by their correlations with structural ...

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    17. Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral Domain Optical Coherence Tomography

      Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral Domain Optical Coherence Tomography

      Purpose: To report the retinal nerve fiber layer (RNFL) defect volume deviation according to structural RNFL loss in RNFL thickness maps Methods: RNFL defect is defined in RNFL thickness maps by the degree of RNFL loss. A 20% to 70% degree of RNFL loss was set with a 1% interval as the reference level for determining the boundary of RNFL defects. Each individual RNFL thickness map was compared to a normative database map and the region below the reference level was identified as an RNFL defect. The RNFL defect volume was calculated by summing the volumes of each pixel inside ...

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    18. Retinal Nerve Fiber Layer Volume Measurements in Healthy Subjects Using Spectral Domain Optical Coherence Tomography

      Retinal Nerve Fiber Layer Volume Measurements in Healthy Subjects Using Spectral Domain Optical Coherence Tomography

      Purpose: To report retinal nerve fiber layer (RNFL) volume measurement using spectral domain optical coherence tomography (SD-OCT). We determined the characteristics and effecting factors of the RNFL volume in healthy eyes. Methods: Eighty-six eyes from 86 healthy volunteers were included. All participants underwent 3D-disc scanning using SD-OCT. We developed a computer program using Matlab software to extract RNFL thickness values from colored topographic RNFL thickness map. Total average, quadrant, and clock-hour RNFL volume were automatically calculated between 2.5 and 5 mm diameter circles using the length, width, and height of each pixel derived from the RNFL thickness map. Results ...

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    19. Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomograph

      Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomograph

      Purpose: To compare the topographic features of localized retinal nerve fiber layer (RNFL) defects presented in red-free RNFL photography and spectral domain optical coherence tomography (SD-OCT), and to evaluate the correlation with structural and functional parameters. Methods: Sixty eyes with localized RNFL defects in red-free RNFL photographs were included. RNFL thickness map and significance map were obtained by SD-OCT. The angular location, angular width, and area of localized RNFL defects were measured and compared among RNFL thickness map, significance map (red, <1% level; yellow, <5% level), and RNFL photograph. The RNFL defect areas were analyzed by their correlations with structural ...

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    20. Measurement of Choroidal Thickness in Normal Eyes Using 3D OCT-1000 Spectral Domain Optical Coherence Tomography

      Measurement of Choroidal Thickness in Normal Eyes Using 3D OCT-1000 Spectral Domain Optical Coherence Tomography

      Purpose To study choroidal thickness and its topographic profile in normal eyes using 3D OCT-1000 spectral domain optical coherence tomography and the correlation with age and refractive error. Methods Fifty-seven eyes (45 individuals) with no visual complaints or ocular disease underwent horizontal and vertical line scanning using 3D OCT-1000. The definition of choroidal thickness was the vertical distance between the posterior edge of the hyper-reflective retinal pigment epithelium and the choroid/sclera junction. Choroidal thickness was measured in the subfoveal area at 500 µm intervals from the fovea to 2,500 µm in the nasal, temporal, superior, and inferior regions ...

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    21. Choroidal Thickness and Volume Mapping by a Six Radial Scan Protocol on Spectral-Domain Optical Coherence Tomography

      Choroidal Thickness and Volume Mapping by a Six Radial Scan Protocol on Spectral-Domain Optical Coherence Tomography

      Purpose To report a 6 radial scan protocol, which simply generates a topographic map of choroidal thickness and volume on a commercial spectral-domain optical coherence tomography (SD-OCT) device. We analyzed the features of the resulting choroidal maps in healthy eyes. Design Prospective, noncomparative case series. Participants Eighty eyes from 40 healthy volunteers who visited the healthcare clinic of Hanyang University Hospital from December 2010 to February 2011. Methods All participants underwent a 6 radial scanning protocol using an SD-OCT device. In a single session, the device produces 6 high-resolution averaging B-scan images. For segmentation of the choroid layer, the reference ...

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    1-21 of 21
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    Choroidal Thickness and Volume Mapping by a Six Radial Scan Protocol on Spectral-Domain Optical Coherence Tomography Measurement of Choroidal Thickness in Normal Eyes Using 3D OCT-1000 Spectral Domain Optical Coherence Tomography Quantitative Analysis of Localized Retinal Nerve Fiber Layer Defects Using Spectral Domain Optical Coherence Tomograph Retinal Nerve Fiber Layer Volume Measurements in Healthy Subjects Using Spectral Domain Optical Coherence Tomography Retinal Nerve Fiber Layer Defect Volume Deviation Analysis Using Spectral Domain Optical Coherence Tomography The Effect of Optic Disc Center Displacement on Retinal Nerve Fiber Layer Measurement Determined by Spectral Domain Optical Coherence Tomography Optical coherence tomography angiography vessel density mapping at various retinal layers in healthy and normal tension glaucoma eyes Ganglion Cell–Inner Plexiform Layer Change Detected by Optical Coherence Tomography Indicates Progression in Advanced Glaucoma Quantitative optical coherence tomography angiography of macular vascular structure and foveal avascular zone in glaucoma Glaucoma Diagnostic Capabilities of Foveal Avascular Zone Parameters Using Optical Coherence Tomography Angiography According to Visual Field Defect Location New insights from non-invasive imaging: from prospection of skin photodamages to training with mobile application Short-sighted woman assumes debilitating headaches mean she needs new glasses but discovers she has multiple sclerosis