1. Articles from Carol Y. Cheung

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    1. Reliability of foveal avascular zone metrics automatically measured by Cirrus optical coherence tomography angiography in healthy subjects

      Reliability of foveal avascular zone metrics automatically measured by Cirrus optical coherence tomography angiography in healthy subjects

      Purpose To investigate the reliability of the foveal avascular zone (FAZ) metrics automatically measured using Cirrus optical coherence tomography angiography (OCTA) embedded algorithm compared to human manual measurement. Methods Thirty-five eyes of 35 healthy subjects were enrolled and scanned four times continuously on Zeiss Cirrus HD-OCT 5000. The FAZ metrics (area, circularity and perimeter) of the superficial capillary plexus were measured automatically using the embedded tool and manually measured by the two independent observers using ImageJ. The repeatability of the four scans within all methods of measurements was calculated. The agreement of the manual vs automated measurement was also analyzed ...

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    2. Detection of glaucomatous optic neuropathy with spectral-domain optical coherence tomography: a retrospective training and validation deep-learning analysis

      Detection of glaucomatous optic neuropathy with spectral-domain optical coherence tomography: a retrospective training and validation deep-learning analysis

      Background Spectral-domain optical coherence tomography (SDOCT) can be used to detect glaucomatous optic neuropathy, but human expertise in interpretation of SDOCT is limited. We aimed to develop and validate a three-dimensional (3D) deep-learning system using SDOCT volumes to detect glaucomatous optic neuropathy. Methods We retrospectively collected a dataset including 4877 SDOCT volumes of optic disc cube for training (60%), testing (20%), and primary validation (20%) from electronic medical and research records at the Chinese University of Hong Kong Eye Centre (Hong Kong, China) and the Hong Kong Eye Hospital (Hong Kong, China). Residual network was used to build the 3D ...

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    3. Unifying Structure Analysis and Surrogate-driven Function Regression for Glaucoma OCT Image Screening

      Unifying Structure Analysis and Surrogate-driven Function Regression for Glaucoma OCT Image Screening

      Optical Coherence Tomography (OCT) imaging plays an important role in glaucoma diagnosis in clinical practice. Early detection and timely treatment can prevent glaucoma patients from permanent vision loss. However, only a dearth of automated methods has been developed based on OCT images for glaucoma study. In this paper, we present a novel framework to effectively classify glaucoma OCT images from normal ones. A semi-supervised learning strategy with smoothness assumption is applied for surrogate assignment of missing function regression labels. Besides, the proposed multi-task learning network is capable of exploring the structure and function relationship from the OCT image and visual ...

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    4. Optical Coherence Tomography Angiography Metrics Predict Progression of Diabetic Retinopathy and Development of Diabetic Macular Edema: A Prospective Study

      Optical Coherence Tomography Angiography Metrics Predict Progression of Diabetic Retinopathy and Development of Diabetic Macular Edema: A Prospective Study

      Purpose To prospectively determine the relationship of optical coherence tomography angiography (OCTA) metrics to diabetic retinopathy (DR) progression and development of diabetic macular edema (DME). Design: Prospective, observational study. Participants Two hundred and five eyes from 129 patients with diabetes mellitus followed up for at least 2 years. Methods All subjects underwent OCTA with a swept-source OCT (DRI-OCT Triton, Topcon, Inc, Tokyo, Japan). Individual OCTA images of superficial capillary plexus (SCP) and deep capillary plexus (DCP) were generated by IMAGEnet6. After quality check, automated measurements of foveal avascular zone (FAZ) area, FAZ circularity, vessel density (VD) and fractal dimension (FD ...

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    5. Artificial Intelligence in Diabetic Eye Disease Screening

      Artificial Intelligence in Diabetic Eye Disease Screening

      Systematic or national screening programs for diabetic retinopathy (DR) and diabetic macular edema (DME), using digital fundus photography and optical coherence tomography (OCT), are currently implemented at primary care level, aiming to provide timely referral for vision-threatening DR and DME to ophthalmologists for timely treatment and vision loss prevention. However, interpretation of retinal images requires specialized knowledge and expertise in diabetic eye disease. Furthermore, current DR screening programs are capital- and labor-intensive, which makes it difficult to rapidly scale up and expand diabetic eye screening to meet the needs of this growing global epidemic. Deep learning (DL), a new branch ...

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    6. Spectral Domain-Optical Coherence Tomography Measurements in Alzheimer’s Disease: A Systematic Review and Meta-analysis

      Spectral Domain-Optical Coherence Tomography Measurements in Alzheimer’s Disease: A Systematic Review and Meta-analysis

      Topic Optical coherence tomography (OCT) is a non-invasive tool to measure specific retinal layers in the eye. The relationship of retinal spectral domain-OCT (SD-OCT) measurements with Alzheimer’s Disease (AD) and mild cognitive impairment (MCI) remains unclear. Hence, we conducted a systematic review and meta-analysis to examine the SD-OCT measurements in AD and MCI. Clinical Relevance Current methods of diagnosing early AD are expensive and invasive. Retinal measurements of SD-OCT, which are non-invasive, technically simple and inexpensive, are potential biomarkers of AD. Methods We conducted a literature search in PubMed and EMBASE to identify studies published before 31 December 2017 ...

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    7. Quantitative retinal microvasculature in children using swept-source optical coherence tomography: the Hong Kong Children Eye Study

      Quantitative retinal microvasculature in children using swept-source optical coherence tomography: the Hong Kong Children Eye Study

      Aims To evaluate the distributions of quantitative optical coherence tomography angiography (OCT-A) metrics and its associated factors in children. Methods 1059 children aged 6–8 years were recruited from the Hong Kong Children Eye Study. All the participants underwent OCT-A with a swept-source OCT. Retinal microvasculature on superficial capillary plexus was assessed and quantified by a customised automated image analysis programme. Univariable and multiple linear regression analyses were performed to determine systemic (body mass index (BMI), waist circumference, head circumference and blood pressure), demographic and ocular (axial length (AL), macular thickness and volume, retinal nerve fibre layer (RNFL) thickness and ...

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    8. Relationship of intercapillary area with visual acuity in diabetes mellitus: an optical coherence tomography angiography study

      Relationship of intercapillary area with visual acuity in diabetes mellitus: an optical coherence tomography angiography study

      Aim To examine the correlation of best-corrected visual acuity (BCVA) with intercapillary area (ICA) measured from optical coherence tomography angiography (OCT-A) in patients with diabetes, and to compare the strength of associations between BCVA with ICA and other OCT-A metrics. Methods A cross-sectional study involved 447 eyes from 299 patients with diabetes. All participants underwent OCT-A with a swept-source OCT (Triton DRI-OCT, Topcon, Tokyo, Japan). An automated customised MATLAB programme was used to quantify ICA (the mean of the 10 largest areas including foveal avascular zone (FAZ) area (ICA10_FAZ) and excluding FAZ area (ICA10_excFAZ)) and other OCT-A metrics (FAZ area ...

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    9. Repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography macular metrics in healthy subjects

      Repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography macular metrics in healthy subjects

      Purpose To investigate the repeatability, interocular correlation and agreement of quantitative swept-source optical coherence tomography angiography (SS-OCTA) metrics in healthy subjects. Methods Thirty-three healthy normal subjects were enrolled. The macula was scanned four times by an SS-OCTA system using the 3 mm×3 mm mode. The superficial capillary map images were analysed using a MATLAB program. A series of parameters were measured: foveal avascular zone (FAZ) area, FAZ perimeter, FAZ circularity, parafoveal vessel density, fractal dimension and vessel diameter index (VDI). The repeatability of four scans was determined by intraclass correlation coefficient (ICC). Then the averaged results were analysed for ...

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    10. Repeatability and Reproducibility of Retinal Neuronal and Axonal Measures on Spectral-domain Optical Coherence Tomography in Patients with Cognitive Impairment

      Repeatability and Reproducibility of Retinal Neuronal and Axonal Measures on Spectral-domain Optical Coherence Tomography in Patients with Cognitive Impairment

      Background: With increasing interest in determining if measurement of retinal neuronal structure with spectral-domain optical coherence tomography (SD-OCT) is useful in accessing neurodegenerative process in cognitive decline and development of dementia, it is important to evaluate whether the SD-OCT measurements are repeatable and reproducible in patients with Alzheimer’s disease (AD) or mild cognitive impairment (MCI). Methods: This is a retrospective cohort study. Patients with AD or MCI with no change in global clinical dementia rating (CDR) score at 1-year follow-up were eligible to be included. (GC-IPL) Macular ganglion-cell inner plexiform layer (GC-IPL) and peripapillary retinal nerve fiver layer (RNFL ...

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    11. Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

      Determinants of Quantitative Optical Coherence Tomography Angiography Metrics in Patients with Diabetes

      Early microvascular damage in diabetes (e.g. capillary nonperfusion and ischemia) can now be assessed and quantified with optical coherence tomography-angiography (OCT-A). The morphology of vascular tissue is indeed affected by different factors; however, there is a paucity of data examining whether OCT-A metrics are influenced by ocular, systemic and demographic variables in subjects with diabetes. We conducted an observational cross-sectional study and included 434 eyes from 286 patients with diabetes. Foveal avascular zone (FAZ) area, FAZ circularity, total and parafoveal vessel density (VD), fractal dimension (FD), and vessel diameter index (VDI) from the superficial capillary plexus OCT-angiogram were measured ...

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    12. Factors affecting signal strength in spectral-domain optical coherence tomography

      Factors affecting signal strength in spectral-domain optical coherence tomography

      Purpose To identify ocular factors that affect signal strength in spectral-domain optical coherence tomography (SD-OCT). Methods Data from 1312 participants of the population-based Singapore Malay Eye Study-2 (SiMES-2) were included in the analysis. All participants underwent standardized ophthalmic examination, including measurements of best-corrected visual acuity (BCVA), refractive error, axial length, corneal curvature and presence of cataracts. Optic disc and macular cube scans were acquired using the Cirrus HD-OCT (software version 6.0, Carl Zeiss Meditec, Dublin, CA, USA). Signal strength of the optical coherence tomography (OCT) scan was recorded for each study eye. Multivariable linear regression analyses were performed to ...

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    13. Optical coherence tomography angiography in acute non-arteritic anterior ischaemic optic neuropathy

      Optical coherence tomography angiography in acute non-arteritic anterior ischaemic optic neuropathy

      Purpose To characterise vascular changes in eyes with acute non-arteritic anterior ischaemic optic neuropathy (NAION), using optical coherence tomography angiography (OCT-A) imaging. Methods This hospital-based observational case-control study included included five patients with acute NAION (6 eyes), within 7 days after onset of symptoms and 19 age-matched healthy controls (19 eyes). OCT-A (RTVue XR 100; Optovue, Fremont, California, USA), covering a 4.5×4.5 mm scan area, was used to evaluate peripapillary blood flow in cases and controls. The flow densities at the retinal and choroidal level were measured using the split-spectrum amplitude-decorrelation angiography algorithm. Results The mean age ...

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    14. Associated factors for visibility and width of retrobulbar subarachnoid space on swept-source optical coherence tomography in high myopia

      Associated factors for visibility and width of retrobulbar subarachnoid space on swept-source optical coherence tomography in high myopia

      Subarachnoid space (SAS) around optic nerve can be visible with swept-source optical coherence tomography (SS-OCT). However, the relevant factors for its visibility and width have not been reported. In this prospective study, 193 eyes with high myopia were evaluated by SS-OCT. The relationship between age, gender, axial length, optic disc area, parapapillary atrophy (PPA) area, peripapillary choroidal thickness with the visibility and width of SAS were assessed. The results showed that SAS was observed in 125 (64.8%) and not observed in 68 (35.2%) eyes. Visibility of SAS is associated with long axial length, high myopia, thin choroid, large ...

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    15. Posterior Eye Shape Measurement With Retinal OCT Compared to MRI

      Posterior Eye Shape Measurement With Retinal OCT Compared to MRI

      Purpose : Posterior eye shape assessment by magnetic resonance imaging (MRI) is used to study myopia. We tested the hypothesis that optical coherence tomography (OCT), as an alternative, could measure posterior eye shape similarly to MRI. Methods : Macular spectral-domain OCT and brain MRI images previously acquired as part of the Singapore Epidemiology of Eye Diseases study were analyzed. The right eye in the MRI and OCT images was automatically segmented. Optical coherence tomography segmentations were corrected for optical and display distortions requiring biometry data. The segmentations were fitted to spheres and ellipsoids to obtain the posterior eye radius of curvature ( R ...

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    16. Retinal Imaging Techniques for Diabetic Retinopathy Screening

      Retinal Imaging Techniques for Diabetic Retinopathy Screening

      Due to the increasing prevalence of diabetes mellitus, demand for diabetic retinopathy (DR) screening platforms is steeply increasing. Early detection and treatment of DR are key public health interventions that can greatly reduce the likelihood of vision loss. Current DR screening programs typically employ retinal fundus photography, which relies on skilled readers for manual DR assessment. However, this is labor-intensive and suffers from inconsistency across sites. Hence, there has been a recent proliferation of automated retinal image analysis software that may potentially alleviate this burden cost-effectively. Furthermore, current screening programs based on 2-dimensional fundus photography do not effectively screen for ...

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    17. Repeatability of Perimacular Ganglion Cell Complex Analysis with Spectral-Domain Optical Coherence Tomography

      Repeatability of Perimacular Ganglion Cell Complex Analysis with Spectral-Domain Optical Coherence Tomography

      Purpose. To assess the repeatability of spectral-domain optical coherence tomography to measure macular and perimacular ganglion cell complex thicknesses and compare retinal ganglion cell parameters between algorithms. Methods. Ninety-two nonglaucomatous eyes from 92 participants underwent macular and perimacular ganglion cell complex thickness measurement using OCT-HS100 Glaucoma 3D algorithm and these measurements were repeated for 34 subjects. All subjects also had macular ganglion cellinner plexiform layer thickness measured by Cirrus HD-OCT Ganglion Cell Analysis algorithm. Intraclass correlation coefficient and Pearson’s correlation analyses were performed. Results. Subfields of both macular and perimacular ganglion cell complex thicknesses had high intraclass correlation coefficient ...

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    18. Relationship of ocular and systemic factors to the visibility of choroidal–scleral interface using spectral domain optical coherence tomography

      Relationship of ocular and systemic factors to the visibility of choroidal–scleral interface using spectral domain optical coherence tomography

      Purpose To assess the visibility of the choroidal–scleral interface (CSI) from spectral domain optical coherence tomography (SD-OCT) and evaluate the ocular and systemic factors influencing the visibility of CSI in healthy eyes from population-based Malay sample. Methods Participants were consecutively recruited from the population-based Singapore Malay Eye Study-2 (SiMES-2). SD-OCT images were obtained by Spectralis OCT with enhanced depth imaging (EDI) mode. Visibility of CSI was assessed by a grading system ranging from 0 to 2 scores. The reliability of choroidal thickness measurement in different grades of CSI visibility was assessed using intraclass correlation coefficient. Ordinal regression analyses were ...

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    19. Retinal neurodegeneration on optical coherence tomography and cerebral atrophy

      Retinal neurodegeneration on optical coherence tomography and cerebral atrophy

      Neurodegeneration in dementia is mainly evaluated by assessing cerebral atrophy, while retinal neurodegeneration can be quantified in vivo using optical coherence tomography (OCT). We examined the association of retinal nerve fibre layer (RNFL) and ganglion cell-inner plexiform layer (GC–IPL) thinning with global and regional cerebral atrophy on magnetic resonance imaging (MRI). Malay participants aged 60–80 years from the Epidemiology of Dementia in Singapore Study underwent comprehensive examinations, including 3-Tesla cranial MRI. RNFL and GC-IPL thicknesses were obtained from spectral domain-OCT; and cerebral grey and white matter volumes were obtained from MRI scans using a validated segmentation tool. Linear ...

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    20. Sectoral variations of iridocorneal angle width and iris volume in Chinese Singaporeans: a swept-source optical coherence tomography study

      Sectoral variations of iridocorneal angle width and iris volume in Chinese Singaporeans: a swept-source optical coherence tomography study

      Purpose To assess variations in the iridocorneal angle width and iris volume in Chinese subjects using swept-source optical coherence tomography (SS-OCT). Methods Consecutive subjects, aged 40–80 years, with no previous ophthalmic problems were recruited from a population-based study of Chinese Singaporeans. All subjects underwent 360° SS-OCT (SS-1000 CASIA, Tomey Corporation, Nagoya, Japan) angle imaging and gonioscopy in one randomly selected eye in the dark. For each eye, 16 frames (11.25° apart) were selected for analysis from 128 cross-sectional images, and measurements of the trabecular iris space area 750 μm from the scleral spur (TISA750) and iris volume were ...

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    21. Assessment of trabecular meshwork width using swept source optical coherence tomography

      Assessment of trabecular meshwork width using swept source optical coherence tomography

      Purpose Measurements of the angle width by ultrasound biomicroscopy or anterior segment optical coherence tomography are usually performed 500 μm from the scleral spur, as the anterior part of trabecular meshwork (TM) is assumed to lie within this distance. The aim of this study was to measure TM width using swept source optical coherence tomography (SS-OCT, CASIA SS-1000, Tomey Corporation, Nagoya, Japan), and to investigate factors influencing this measurement. Methods Participants underwent gonioscopy and SS-OCT imaging in the dark. High-definition SS-OCT images were corrected for refractive distortion; and customized software (ImageJ; National Institutes of Health, Bethesda, MD, USA) was utilized ...

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    22. Analysis of Anterior Segment Dynamics Using Anterior Segment Optical Coherence Tomography Before and After Laser Peripheral Iridotomy

      Analysis of Anterior Segment Dynamics Using Anterior Segment Optical Coherence Tomography Before and After Laser Peripheral Iridotomy

      Objective To evaluate changes in the speed of pupil constriction and in anterior segment parameters after laser peripheral iridotomy (LPI) in patients with angle closure using anterior segment optical coherence tomography. Methods In this prospective observational study, videos of pupil and anterior segment changes in response to illumination were captured with real-time video recording using anterior segment optical coherence tomography and were analyzed frame by frame before and after LPI. Customized software was used to measure the speed of pupil constriction and changes in anterior chamber depth and anterior chamber area, as well as iris thickness at 750 μm from ...

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    23. Determinants of Ganglion Cell–Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Determinants of Ganglion Cell–Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Purpose. To determine the distribution, variation, and determinants of ganglion cell–inner plexiform layer (GC-IPL) thickness in nonglaucomatous eyes measured by high-definition optical coherence tomography (HD-OCT). Methods. Six hundred twenty-three Chinese adults aged 40 to 80 years were consecutively recruited from a population-based study. All subjects underwent a standardized interview, ophthalmic examination, and automated perimetry. HD-OCT with macular cube protocol was used to measure the GC-IPL thickness. Univariate and multiple linear regression analyses were performed to examine the relationship between GC-IPL thickness with ocular and systemic factors. Results. The mean (±SD) age of study subjects was 52.84 ± 6.14 ...

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    24. Determinants of Ganglion Cell-Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Determinants of Ganglion Cell-Inner Plexiform Layer Thickness Measured by High-Definition Optical Coherence Tomography

      Purpose. To determine the distribution, variation and determinants of ganglion cell-inner plexiform layer (GC-IPL) thickness in non-glaucomatous eyes measured by high-definition optical coherence tomography (HD-OCT). Methods. 623 Chinese adults aged 40-80 years were consecutively recruited from a population-based study. All subjects underwent a standardized interview, ophthalmic examination and automated perimetry. HD-OCT (Cirrus, software version 6.0, Carl Zeiss Meditec, Dublin, CA) with macular cube protocol was used to measure the GC-IPL thickness. Univariate and multiple linear regression analyses were performed to examine the relationship between GC-IPL thickness with ocular and systemic factors. Results. The mean (± SD) age of study subjects ...

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