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    1. Numerical method for axial motion artifact correction in retinal spectral-domain optical coherence tomography

      Numerical method for axial motion artifact correction in retinal spectral-domain optical coherence tomography

      A numerical method that compensates image distortions caused by random fluctuations of the distance to an object in spectral-domain optical coherence tomography (SD OCT) has been proposed and verified experimentally. The proposed method is based on the analysis of the phase shifts between adjacent scans that are caused by micrometer-scale displacements and the subsequent compensation for the displacements through phase-frequency correction in the spectral space. The efficiency of the method is demonstrated in model experiments with harmonic and random movements of a scattering object as well as during in vivo imaging of the retina of the human eye.

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    2. Characteristics of diffuse retinal nerve fiber layer defects in red-free photographs as observed in optical coherence tomography en face images

      Characteristics of diffuse retinal nerve fiber layer defects in red-free photographs as observed in optical coherence tomography en face images

      Backgroud To determine whether diffuse retinal nerve fiber layer (RNFL) defects, identified on red-free fundus photographs, could be identified on optical coherence tomography (OCT) en face structural images and to evaluate which factors are related to the different recognition patterns on en face images. Methods This retrospective, cross-sectional study included open-angle glaucoma eyes with diffuse RNFL defects in the inferior hemifield, identified in red-free photographs. The corresponding OCT en face structural images were divided into 3 groups: (1) no defect, (2) localized defect, and (3) diffuse defect. We compared the demographic and clinical ocular characteristics among the groups. Results A ...

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      Mentions: Korea University
    3. Frequency-domain optical coherence tomography system in the terahertz region

      Frequency-domain optical coherence tomography system in the terahertz region

      In this study, a frequency-domain optical coherence tomography (FD-OCT) system in the terahertz frequency range was developed. To generate tunable continuous-wave terahertz radiation, the outputs of two near-infrared external cavity diode lasers were mixed in an antenna-coupled photo-mixer. Using the FD-OCT system, tomographic profiling of the front and back surfaces of a high-resistivity silicon plate was realized.

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      Mentions: Osaka University
    4. Novel biomarker of sphericity and cylindricity indices in volume-rendering optical coherence tomography angiography in normal and diabetic eyes: a preliminary study

      Novel biomarker of sphericity and cylindricity indices in volume-rendering optical coherence tomography angiography in normal and diabetic eyes: a preliminary study

      Purpose Preliminary to evaluate geometric indices (vessel sphericity and cylindricity) for volume-rendered optical coherence tomography angiography (OCTA) in healthy and diabetic eyes. Methods Twenty-six eyes of 13 healthy subjects and 12 eyes of patients with central ischemic, non-proliferative diabetic retinopathy were included. OCTA volume and surface area of the foveal vessels were measured and compared to determine OCTA sphericity and cylindricity indices and surface efficiency (SE). Results The overall average OCTA volume in healthy was 0.49 ± 0.09 mm 3 (standard deviation [SD]), compared to 0.44 ± 0.07 mm 3 (SD) in the diabetic eyes (difference in means ...

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    5. Efficacy of optical frequency-domain imaging in detecting peripheral artery disease: a single-center open-label, single-arm study protocol

      Efficacy of optical frequency-domain imaging in detecting peripheral artery disease: a single-center open-label, single-arm study protocol

      Intravascular optical coherence tomography is a high-resolution intracoronary imaging modality, providing a microscopic image of intravascular features. However, it has lower penetration depth than intravascular ultrasound. Recently, a second-generation optical frequency-domain imaging (OFDI) technique has been developed to provide greater penetration depth and faster pullback speed. However, there is little evidence supporting the efficacy of OFDI in patients with peripheral artery disease (PAD) undergoing endovascular treatment (EVT). We aimed to evaluate the ability of OFDI to visualize vessel walls from the superficial femoral artery (SFA) to the below-knee (BK) arteries, as well as the coronary arteries. This clinical trial is ...

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    6. Microvascular retinal changes in pre-clinical diabetic retinopathy as detected by optical coherence tomographic angiography

      Microvascular retinal changes in pre-clinical diabetic retinopathy as detected by optical coherence tomographic angiography

      Purpose To investigate microvascular abnormalities in diabetic patients without conventional clinical signs of diabetic retinopathy (DR). Methods In this cross-sectional observational cohort study, the study group included randomly chosen participants of a community-based cohort with diabetes type 2 without DR, and the control group consisted of non-diabetic individuals from a population-based study. All participants underwent optical coherence tomographic angiography (OCTA). Results Upon OCTA, 118 (40.4%) eyes of the study group ( n  = 292 eyes) showed microvascular abnormalities including foveal avascular zone erosion (95 (32.5%) eyes), non-perfusion areas in the superficial and deep retinal layers (39 (13.4%) eyes and ...

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    7. OCT and Imaging in Central Nervous System Diseases: The Eye as a Window to the Brain (Textbook)

      OCT and Imaging in Central Nervous System Diseases: The Eye as a Window to the Brain (Textbook)

      The second edition of OCT and Imaging in Central Nervous System Diseases offers updated state-of-the-art advances using optical coherence tomography (OCT) regrading neuronal loss within the retina. Detailed information on the OCT imaging and interpretation is provided for the evaluation of disease progression in numerous neurodegenerative disorders and as a biological marker of neuroaxonal injury. Covering disorders like multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, intracranial hypertension, Friedreich’s ataxia, schizophrenia, hereditary optic neuropathies, glaucoma, and amblyopia, readers will given insights into effects on the retina and the and optic nerve. Individual chapters are also devoted to OCT technique ...

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    8. Topographic correlation between multifocal electroretinography, microperimetry, and spectral-domain optical coherence tomography of the macula in patients with birdshot chorioretinopathy

      Topographic correlation between multifocal electroretinography, microperimetry, and spectral-domain optical coherence tomography of the macula in patients with birdshot chorioretinopathy

      Purpose To correlate the findings of retinal function with multifocal electroretinogram (mfERG), microperimetry (MP), and structural assessments with spectral-domain optical coherence tomography (SD-OCT) in topographically corresponding areas of the macula of patients with birdshot chorioretinopathy (BSCR). Methods Patients diagnosed with BSCR by clinical and imaging findings were included in the study. The mfERG was performed using 61 hexagon stimulus patterns grouped into 5 rings (Diagnosys Inc., USA). Individual responses [N1-P1 amplitudes in nanovolt (NV)/degree 2 and P1 implicit time in milliseconds (msec)] for each hexagon in the central 3 rings (R1, 0°–2.3°; R2,2.3°–7.7 ...

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    9. Noninvasive Diagnosis of Regional Alteration of Retinal Morphology and Structure with Optical Coherence Tomography in Rodents

      Noninvasive Diagnosis of Regional Alteration of Retinal Morphology and Structure with Optical Coherence Tomography in Rodents

      Spectral-domain optical coherence tomography (SD-OCT) produces high-resolution images of retinal cross sections and is becoming a method of choice for in vivo analyses of retinal morphology in rodents. We have adopted this technology to identify and analyze alterations of retinal structure, particularly those with regional and subtle changes. In this technical brief, we will demonstrate the use of SD-OCT in identifying subtle changes in retinal structure and morphology due to the effect of mosaic gene deletion in conditional knockout mice and of uneven distribution of intravitreally delivered compounds, review the application of SD-OCT in measuring pathological lesion volumes, and discuss ...

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    10. Feasibility evaluation of micro-optical coherence tomography (μOCT) for rapid brain tumor type and grade discriminations: μOCT images versus pathology

      Feasibility evaluation of micro-optical coherence tomography (μOCT) for rapid brain tumor type and grade discriminations: μOCT images versus pathology

      Background Precise identification, discrimination and assessment of central nervous system (CNS) tumors is of critical importance to brain neoplasm treatment. Due to the complexity and limited resolutions of the existing diagnostic tools, however, it is difficult to identify the tumors and their boundaries precisely in clinical practice, and thus, the conventional way of brain neoplasm treatment relies mainly on the experiences of neurosurgeons to make resection decisions in the surgery process. The purpose of this study is to explore the potential of Micro-optical coherence tomography (μOCT) as an intraoperative diagnostic imaging tool for identifying and discriminating glioma and meningioma with ...

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    11. Linear and planar reflection artifacts on swept-source and spectral-domain optical coherence tomography due to hyperreflective crystalline deposits

      Linear and planar reflection artifacts on swept-source and spectral-domain optical coherence tomography due to hyperreflective crystalline deposits

      Purpose To describe novel spectral-domain (SD) and swept-source (SS) optical coherence tomography (OCT) linear and planar reflection artifacts produced by hyperreflective crystalline deposits (HCD). Methods Imaging from 10 eyes with HCD producing linear and planar artifacts on OCT was retrospectively analyzed. All eyes had SD-OCT (Spectralis HRA + OCT, Heidelberg Engineering, Germany) and SS-OCT angiography (PLEX Elite 9000, Carl Zeiss Meditec, Inc., Dublin, CA) acquired on the same day. The horizontal extent of planar artifacts and the corresponding HCD on B-scans was measured using a digital caliper. Artifact features from HCD in eyes with non-neovascular age-related macular degeneration (AMD) were analyzed ...

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    12. Optical coherence tomography angiography in uveitis

      Optical coherence tomography angiography in uveitis

      Before the introduction of optical coherence tomography angiography (OCTA) in the early 2000s, dye-based angiography was considered the “gold standard” for the diagnosis and monitoring of ocular inflammation. OCTA is a novel technique, which demonstrates capillary networks based on the amount of light returned from moving blood cells, providing further information on pathophysiological changes in uveitis. The aim of this review is to describe the basic principles of OCTA and its application to ocular inflammatory disorders. It particularly emphasizes on its contribution not only in the diagnosis and management of the disease but also in the identification of possible complications ...

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    13. Intra and inter-rater agreement of inflammatory choroidal neovascular membrane measurements using optical coherence tomography angiography

      Intra and inter-rater agreement of inflammatory choroidal neovascular membrane measurements using optical coherence tomography angiography

      Purpose Automated measurement algorithm software is not routinely available in optical coherence tomography angiography (OCTA) devices and manual measurement of choroidal neovascular membrane (CNVM) size is necessary. Our aim was to determine intra- and inter-rater agreement of inflammatory CNVM manual measurements obtained with OCTA. Methods OCTA (Triton® Topcon Corporation) images in patients with inflammatory CNVM were imported into ImageJ software v1.50 (NIH image). Two experienced observers performed manual area and perimeter measurements independently, and one of the observers performed the same measurements twice. Agreement was evaluated with intraclass correlation coefficients (ICC) and concordance correlation coefficients (CCC). Bland-Altman plots were ...

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    14. Frailty and coronary plaque characteristics on optical coherence tomography

      Frailty and coronary plaque characteristics on optical coherence tomography

      The relationship between frailty and plaque characteristics is unclear and was investigated by optical coherence tomography (OCT) in this study. One hundred and four patients undergoing OCT before percutaneous coronary intervention were evaluated. Frailty was defined as a clinical frailty scale score of ≧6. Frailty was found in 16% of the patients (17/104). Compared with the nonfrail patients, frail patients showed significantly lower body mass index (BMI; 20.8 ± 4.0 kg/m 2 vs. 25.0 ± 3.9 kg/m 2 , P  < 0.001), less dyslipidemia [47% (8/17) vs. 75% (65/87), P  = 0.023], lower triglycerides ...

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    15. Intracranial pressure patterns in children with craniosynostosis utilizing optical coherence tomography

      Intracranial pressure patterns in children with craniosynostosis utilizing optical coherence tomography

      Background Better understanding the incidence and patterns of elevated intracranial pressure (ICP) in patients with craniosynostosis may facilitate more timely intervention to alter neurocognitive outcomes. Spectral-domain optical coherence tomography (OCT) of the retina can non-invasively diagnose elevated ICP, and has demonstrated high sensitivity and specificity among patients with craniosynostosis. This study sought to characterize patterns of elevated ICP among patients with craniosynostosis. Methods Quantitative retinal parameters were prospectively assessed in both eyes of patients with craniosynostosis using spectral-domain OCT. Based on retinal OCT thresholds associated with elevated ICP (> 15 mmHg), subjects were assigned an OCT diagnosis of elevated or non-elevated ...

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    16. Demineralization detection in orthodontics using an ophthalmic optical coherence tomography device equipped with a multicolor fluorescence module

      Demineralization detection in orthodontics using an ophthalmic optical coherence tomography device equipped with a multicolor fluorescence module

      Objectives Demineralizations such as white spot lesions are among the most prevalent side effects during orthodontic treatment. Fluorescence devices, including quantitative light-induced fluorescence (QLF), exploiting the intrinsic fluorescence of enamel and teeth and most recently optical coherence tomography (OCT) were introduced for early demineralization detection. In addition to near-infrared OCT scanning, multicolor modules allow for imaging with different laser wavelengths and the detection of reflective- and fluorescent light. The aim of this study was to evaluate a modified multicolor ophthalmic OCT device for the detection of early carious lesions in vitro and in vivo. Materials and methods Twenty-seven extracted lesion ...

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    17. Reflections on the Utility of the Retina as a Biomarker for Alzheimer’s Disease: A Literature Review

      Reflections on the Utility of the Retina as a Biomarker for Alzheimer’s Disease: A Literature Review

      As a part of the central nervous system, the retina may reflect both physiologic processes and abnormalities related to diseases of the brain. Indeed, a concerted effort has been put forth to understand how Alzheimer’s disease (AD) pathology may manifest in the retina as a means to assess the state of the AD brain. The development and refinement of ophthalmologic techniques for studying the retina in vivo have produced evidence of retinal degeneration in AD diagnosed patients. In this review, we will discuss retinal imaging techniques implemented to study the changes in AD retina as well as highlight the ...

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      Mentions: UCSD UCSF
    18. Quantitative analysis of retinal and choroidal microvascular parameters using optical coherence tomography angiography in children with nephrotic syndrome: a pilot study

      Quantitative analysis of retinal and choroidal microvascular parameters using optical coherence tomography angiography in children with nephrotic syndrome: a pilot study

      Purpose To study the retinal and choroidal microvascular parameters in children with nephrotic syndrome (NS). Methods This is a cross-sectional study. Optical coherence tomography angiography was used to evaluate the changes of retinal and choroidal microvessels in patients with NS. Thirty NS children and 20 normal controls were included in this study. The macular vessel density (VD) of the superficial capillary plexus (SCP), deep capillary plexus (DCP), choroid capillary plexus (CCP), and foveal avascular zone (FAZ) area of the SCP and DCP was quantitatively calculated. Clinical data including serum protein, blood lipid, uric acid, urea, serum creatinine, urinary protein concentration ...

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    19. Optical coherence tomography angiography findings of type 1 diabetic patients with diabetic retinopathy, in comparison with type 2 patients

      Optical coherence tomography angiography findings of type 1 diabetic patients with diabetic retinopathy, in comparison with type 2 patients

      Purpose To compare optical coherence tomography angiography (OCT-A) parameters between type 1 and type 2 diabetic patients with diabetic retinopathy (DR). Methods A total of 70 patients with type 1 diabetes and 70 with type 2 diabetes were retrospectively analyzed. DR was graded as no DR, mild nonproliferative DR (NPDR), moderate NPDR, severe NPDR, and proliferative DR (PDR). Using OCT-A, the foveal avascular zone (FAZ) area (mm 2 ) and vascular density (VD) (%) were calculated in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). Results In both type 1 and 2 diabetes patients, the FAZ area (mm 2 ) in ...

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    20. Optical coherence tomography angiography-derived flow density: a review of the influencing factors

      Optical coherence tomography angiography-derived flow density: a review of the influencing factors

      Research interest in the possibility of quantifying macular and optic nerve head perfusion through optical coherence tomography angiography (OCTA) is rapidly advancing. Numerous scientific trials have furthered our understanding of the capabilities and the limitations of this novel technology, while applying OCTA to various ocular pathologies. In recent years, different parameters such as age, gender, intraocular pressure, spherical equivalent, physical activity, systemic diseases, and medication have been shown to have a significant impact on quantitative OCTA metrics. Since OCTA is likely to remain a “hot topic” in the near future, it is crucial to be aware of influencing factors in ...

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    21. Changes in retinal and choriocapillaris density in diabetic patients receiving anti-vascular endothelial growth factor treatment using optical coherence tomography angiography

      Changes in retinal and choriocapillaris density in diabetic patients receiving anti-vascular endothelial growth factor treatment using optical coherence tomography angiography

      Background Optical coherence tomography angiography (OCTA) enables detailed, non-invasive assessment of ocular vasculature. This study uses OCTA imaging to evaluate choriocapillaris and retinal capillary perfusion density (CPD) changes in diabetic retinopathy following anti-vascular endothelial growth factor (VEGF) treatment. Methods Records of 38 eyes at a single institution were reviewed, grouped as non-diabetic controls (19 eyes), diabetes mellitus patients with diabetic retinopathy (DR, 19 eyes) and macular edema (DME). DR eyes were imaged at baseline, 6-months and 12-months after anti-VEGF treatment. Quantitative analyses assessed CPD of the choriocapillaris and retinal plexus. Results DR eyes showed decreased choriocapillaris whole-image CPD (62.6 ...

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    22. Automatic quantification of superficial foveal avascular zone in optical coherence tomography angiography implemented with deep learning

      Automatic quantification of superficial foveal avascular zone in optical coherence tomography angiography implemented with deep learning

      An accurate segmentation and quantification of the superficial foveal avascular zone (sFAZ) is important to facilitate the diagnosis and treatment of many retinal diseases, such as diabetic retinopathy and retinal vein occlusion. We proposed a method based on deep learning for the automatic segmentation and quantification of the sFAZ in optical coherence tomography angiography (OCTA) images with robustness to brightness and contrast (B/C) variations. A dataset of 405 OCTA images from 45 participants was acquired with Zeiss Cirrus HD-OCT 5000 and the ground truth (GT) was manually segmented subsequently. A deep learning network with an encoder–decoder architecture was ...

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    23. Detecting glaucoma based on spectral domain optical coherence tomography imaging of peripapillary retinal nerve fiber layer: a comparison study between hand-crafted features and deep learning model

      Detecting glaucoma based on spectral domain optical coherence tomography imaging of peripapillary retinal nerve fiber layer: a comparison study between hand-crafted features and deep learning model

      Purpose To develop a deep learning (DL) model for automated detection of glaucoma and to compare diagnostic capability against hand-craft features (HCFs) based on spectral domain optical coherence tomography (SD-OCT) peripapillary retinal nerve fiber layer (pRNFL) images. Methods A DL model with pre-trained convolutional neural network (CNN) based was trained using a retrospective training set of 1501 pRNFL OCT images, which included 690 images from 153 glaucoma patients and 811 images from 394 normal subjects. The DL model was further tested in an independent test set of 50 images from 50 glaucoma patients and 52 images from 52 normal subjects ...

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    24. 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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