1. 1-24 of 321 1 2 3 4 ... 12 13 14 »
    1. Identifying characteristic features of the retinal and choroidal vasculature in choroideremia using optical coherence tomography angiography

      Identifying characteristic features of the retinal and choroidal vasculature in choroideremia using optical coherence tomography angiography

      Clinical Study Identifying characteristic features of the retinal and choroidal vasculature in choroideremia using optical coherence tomography angiography A Abbouda , A M Dubis , A R Webster & M Moosajee Abstract Purpose Using optical coherence tomography angiography (OCTA) to investigate the area with flow in the superficial retinal vessel network (SVRN) and choriocapillaris (CC) layer among male subjects with choroideremia (CHM), female carriers, and normal controls to identify vascular changes. Patients and methods Images of SRVN and CC layer were acquired in 9 affected males, 5 female carriers, and 14 age- and gender-matched controls using the Angiovue software of the RTVue XR ...

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    2. Precision of a new ocular biometer in eyes with cataract using swept source optical coherence tomography combined with Placido-disk corneal topography

      Precision of a new ocular biometer in eyes with cataract using swept source optical coherence tomography combined with Placido-disk corneal topography

      The present study was to assess the precision (repeatability and reproducibility) of a new optical biometer (OA-2000, Tomey, Japan) based on swept-source optical coherence tomography (SS-OCT) and Placido disk topography in eyes with cataracts. Seventy-eight eyes from seventy-eight patients with cataracts were evaluated. Axial length (AL), anterior chamber depth (ACD), keratometry (K) over a 2.5 mm and 3.0 mm diameter, lens thickness (LT), central corneal thickness (CCT) and white-to-white (WTW) distance were measured by 2 skilled operators. OA-2000 measurements were highly repeatable and reproducible for all parameters (intraclass correlation, 0.925 to 1.000). OA-2000 derived K-values with ...

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    3. Visualization and quantification of injury to the ciliated epithelium using quantitative flow imaging and speckle variance optical coherence tomography

      Visualization and quantification of injury to the ciliated epithelium using quantitative flow imaging and speckle variance optical coherence tomography

      Mucociliary flow is an important defense mechanism in the lung to remove inhaled pathogens and pollutants. Disruption of ciliary flow can lead to respiratory infections. Multiple factors, from drugs to disease can cause an alteration in ciliary flow. However, less attention has been given to injury of the ciliated epithelium. In this study, we show how optical coherence tomography (OCT) can be used to investigate injury to the ciliated epithelium in a multi-contrast setting. We used particle tracking velocimetry (PTV-OCT) to investigate the cilia-driven flow field and 3D speckle variance imaging to investigate size and extent of injury caused to ...

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    4. OCT Amplitude and Speckle Statistics of Discrete Random Media

      OCT Amplitude and Speckle Statistics of Discrete Random Media

      Speckle, amplitude fluctuations in optical coherence tomography (OCT) images, contains information on sub-resolution structural properties of the imaged sample. Speckle statistics could therefore be utilized in the characterization of biological tissues. However, a rigorous theoretical framework relating OCT speckle statistics to structural tissue properties has yet to be developed. As a first step, we present a theoretical description of OCT speckle, relating the OCT amplitude variance to size and organization for samples of discrete random media (DRM). Starting the calculations from the size and organization of the scattering particles, we analytically find expressions for the OCT amplitude mean, amplitude variance ...

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    5. Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser

      Intravascular Optical Coherence Tomography for Characterization of Atherosclerosis with a 1.7 Micron Swept-Source Laser

      The main cause of acute coronary events, such as thrombosis, is the rupture of atherosclerotic plaques. Typical intravascular optical coherence tomography (IVOCT) imaging systems that utilize a 1.3 μm swept source laser are often used for identifying fibrous cap thickness of plaques, yet cannot provide adequate depth penetration to resolve the size of the lipid pool. Here, we present a novel IVOCT system with a 1.7 μm center wavelength swept light source that can readily penetrate deeper into the tissue because of the longer wavelength and allows for better identification of plaques due to the lipid absorption spectrum ...

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    6. A novel and faster method of manual grading to measure choroidal thickness using optical coherence tomography

      A novel and faster method of manual grading to measure choroidal thickness using optical coherence tomography

      Purpose Choroidal thickness (CT) measurements are typically obtained from manual segmentation of optical coherence tomography (OCT) B-scans. This method is time-consuming. We aimed to describe a novel and faster technique to obtain CT measurements. Patients and methods In a prospective cohort study of 200 healthy eyes, Spectral-Domain OCT with enhanced depth imaging were performed with the Spectralis OCT using standardised imaging protocols. The OCT scans were independently graded by reading centre-certified graders. The standard method of manual adjustment of segmentation boundaries was performed. The new method consisted of adjusting the lower segmentation line to the choroid-scleral boundary to generate the ...

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    7. Visualizing Micro-anatomical Structures of the Posterior Cornea with Micro-optical Coherence Tomography

      Visualizing Micro-anatomical Structures of the Posterior Cornea with Micro-optical Coherence Tomography

      Diagnosis of corneal disease and challenges in corneal transplantation require comprehensive understanding of corneal anatomy, particularly that of the posterior cornea. Micro-optical coherence tomography (µOCT) is a potentially suitable tool to meet this need, owing to its ultrahigh isotropic spatial resolution, high image acquisition rate and depth priority scanning mode. In this study, we explored the ability of µOCT to visualize micro-anatomical structures of the posterior cornea ex vivo and in vivo using small and large animals. µOCT clearly delineated cornea layers and revealed micro-anatomical structures, including not only polygonal endothelial cells, stellate keratocytes, collagen fibres and corneal nerve fibres ...

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    8. Combination of optical coherence tomography and near infrared spectroscopy enhances determination of articular cartilage composition and structure

      Combination of optical coherence tomography and near infrared spectroscopy enhances determination of articular cartilage composition and structure

      Conventional arthroscopic evaluation of articular cartilage is subjective and poorly reproducible. Therefore, implementation of quantitative diagnostic techniques, such as near infrared spectroscopy (NIRS) and optical coherence tomography (OCT), is essential. Locations ( n  = 44) with various cartilage conditions were selected from mature equine fetlock joints ( n  = 5). These locations and their surroundings were measured with NIRS and OCT ( n  = 530). As a reference, cartilage proteoglycan (PG) and collagen contents, and collagen network organization were determined using quantitative microscopy. Additionally, lesion severity visualized in OCT images was graded with an automatic algorithm according to International Cartilage Research Society (ICRS) scoring system. Artificial ...

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    9. An overview of the clinical applications of optical coherence tomography angiography

      An overview of the clinical applications of optical coherence tomography angiography

      Optical coherence tomography angiography (OCTA) has emerged as a novel, non-invasive imaging modality that allows the detailed study of flow within the vascular structures of the eye. Compared to conventional dye angiography, OCTA can produce more detailed, higher resolution images of the vasculature without the added risk of dye injection. In our review, we discuss the advantages and disadvantages of this new technology in comparison to conventional dye angiography. We provide an overview of the current OCTA technology available, compare the various commercial OCTA machines technical specifications and discuss some future software improvements. An approach to the interpretation of OCTA ...

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    10. Visualization and Detection of Ciliary Beating Pattern and Frequency in the Upper Airway using Phase Resolved Doppler Optical Coherence Tomography

      Visualization and Detection of Ciliary Beating Pattern and Frequency in the Upper Airway using Phase Resolved Doppler Optical Coherence Tomography

      Ciliary motion plays a critical role in the overall respiratory health of the upper airway. These cilia beat at a native frequency and in a synchronized pattern to continuously transport foreign particulate trapped in a layer of mucous out of the upper airway. Disruption of ciliary motion can lead to severe respiratory diseases and compromised respiratory function. Currently, the study of cilia requires expensive high speed cameras and high powered microscopes which is unsuitable for in vivo imaging and diagnosis. Doppler based optical coherence tomography has the potential to visualize the microscopic motion of cilia during their beating cycle. We ...

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    11. In vivo assessment of macula in eyes of healthy children 8 to 16 years old using optical coherence tomography angiography

      In vivo assessment of macula in eyes of healthy children 8 to 16 years old using optical coherence tomography angiography

      The purpose of the present study was to investigate the vascular flow density (VD) of macular superficial (SCP), deep capillary plexus (DCP), and choriocapillaris and the size of the foveal avascular zone (FAZ) area in healthy children using optical coherence tomography angiography (OCTA). The potential associations of age, sex, intraocular pressure, body mass index, spherical equivalent, and axial length with OCTA parameters were also investigated. A total of 75 eyes from 75 healthy children were included for analysis, with the mean age 11.51 ± 1.91 years (range, 8–16 years). At the level of the SCP, mean VD and ...

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    12. Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Oblique scanning laser microscopy for simultaneously volumetric structural and molecular imaging using only one raster scan

      Multi-modal three dimensional (3D) optical imaging combining both structural sensitivity and molecular specificity is highly desirable in biomedical research. In this paper, we present a method termed oblique scanning laser microscopy (OSLM) to combine optical coherence tomography (OCT), for simultaneously volumetric structural and molecular imaging with cellular resolution in all three dimensions. Conventional 3D laser scanning fluorescence microscopy requires repeated optical sectioning to create z-stacks in depth. Here, the use of an obliquely scanning laser eliminates the z-stacking process, then allows highly efficient 3D OCT and fluorescence imaging by using only one raster scan. The current setup provides ~3.6 ...

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    13. In vivo photothermal optical coherence tomography of endogenous and exogenous contrast agents in the eye

      In vivo photothermal optical coherence tomography of endogenous and exogenous contrast agents in the eye

      Optical coherence tomography (OCT) has become a standard-of-care in retinal imaging. OCT allows non-invasive imaging of the tissue structure but lacks specificity to contrast agents that could be used for in vivo molecular imaging. Photothermal OCT (PT-OCT) is a functional OCT-based technique that has been developed to detect absorbers in a sample. We demonstrate in vivo PT-OCT in the eye for the first time on both endogenous (melanin) and exogenous (gold nanorods) absorbers. Pigmented mice and albino mice (n = 6 eyes) were used to isolate the photothermal signal from the melanin in the retina. Pigmented mice with laser-induced choroidal neovascularization ...

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    14. The linear artifact in enhanced depth imaging spectral domain optical coherence tomography

      The linear artifact in enhanced depth imaging spectral domain optical coherence tomography

      Optical coherence tomography (OCT) is a valuable ancillary test in the diagnosis and management of chorioretinal disease. The evaluation of choroid thickness using OCT has become the focus of clinical applications. We report a linear artifact that acts as a confounding factor in choroidal thickness measurements by enhanced depth imaging OCT. We found that the linear artifact is located stably at a depth of 485  μ m beneath the retinal pigment epithelium in 81.88% of subjects. The study suggested that the linear artifact was a confounding factor in assessing choroidal thickness and that caution should be used in the interpretation ...

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    15. Speckle-free OCT

      Speckle-free OCT

      Optical coherence tomography (OCT) is a well-established method for in vivo imaging and is widely used in the field of opthamology. Like all coherent imaging techniques, OCT image quality can be reduced by the presence of speckle noise that arises from light scattering within turbid specimens. To reduce speckle noise in OCT, Liba et al . developed an approach called speckle-modulating OCT (SM-OCT). SM-OCT overcomes speckle noise by creating and averaging a large number of scans. Because the speckle patterns in the scans are uncorrelated, they are effectively removed during averaging without compromising resolution. Using their approach, the researchers showed that ...

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    16. Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Murine chronic lymph node window for longitudinal intravital lymph node imaging

      Chronic imaging windows in mice have been developed to allow intravital microscopy of many different organs and have proven to be of paramount importance in advancing our knowledge of normal and disease processes. A model system that allows long-term intravital imaging of lymph nodes would facilitate the study of cell behavior in lymph nodes during the generation of immune responses in a variety of disease settings and during the formation of metastatic lesions in cancer-bearing mice. We describe a chronic lymph node window (CLNW) surgical preparation that allows intravital imaging of the inguinal lymph node in mice. The CLNW is ...

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    17. Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Miniature probe for mapping mechanical properties of vascular lesions using acoustic radiation force optical coherence elastography

      Cardiovascular diseases are the leading cause of fatalities in the United States. Atherosclerotic plaques are one of the primary complications that can lead to strokes and heart attacks if left untreated. It is essential to diagnose the disease early and distinguish vulnerable plaques from harmless ones. Many methods focus on the structural or molecular properties of plaques. Mechanical properties have been shown to change drastically when abnormalities develop in arterial tissue. We report the development of an acoustic radiation force optical coherence elastography (ARF-OCE) system that uses an integrated miniature ultrasound and optical coherence tomography (OCT) probe to map the ...

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    18. Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Optical coherence microscopy as a novel, non-invasive method for the 4D live imaging of early mammalian embryos

      Imaging of living cells based on traditional fluorescence and confocal laser scanning microscopy has delivered an enormous amount of information critical for understanding biological processes in single cells. However, the requirement for a high numerical aperture and fluorescent markers still limits researchers’ ability to visualize the cellular architecture without causing short- and long-term photodamage. Optical coherence microscopy (OCM) is a promising alternative that circumvents the technical limitations of fluorescence imaging techniques and provides unique access to fundamental aspects of early embryonic development, without the requirement for sample pre-processing or labeling. In the present paper, we utilized the internal motion of ...

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    19. Postoperative change in lateral rectus muscle insertion measured by anterior segment optical coherence tomography

      Postoperative change in lateral rectus muscle insertion measured by anterior segment optical coherence tomography

      Aims The aims of this study were to investigate the longitudinal change in lateral rectus (LR) muscle insertion after recession surgery, and to evaluate a relationship between insertion distance and postoperative amount of deviation. Methods We recruited 31 patients who underwent primary LR recession surgery with normal anterior segment structures. An AS-OCT scan of the LR muscle was performed at every visit. Data on sex, age, degree of deviation (prism diopter), and spur-LR insertion distance using AS-OCT were collected at preoperatively and postoperative months 1, 3, and 6. Spur-LR insertion was defined as the shortest distance between the insertion of ...

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    20. Optical coherence tomography analysis of evolution of Bruch’s membrane features in angioid streaks

      Optical coherence tomography analysis of evolution of Bruch’s membrane features in angioid streaks

      Purpose To describe optical coherence tomography (OCT) features in the Bruch’s membrane (BM) of eyes with angioid streaks (AS) and evaluate their evolution over the follow-up. Patients and methods Patients with AS presenting between March 2016 and September 2016 at two tertiary referral centers were consecutively recruited in this study. Eligibility criteria included prior spectral domain (SD)-OCT images, taken at least 3 months before at the same referral center, with automated eye tracking and image alignment modules. Alterations of BM were described and compared to previous scans over the follow-up. Multimodal imaging was used to identify alteration of ...

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    21. Speckle-modulating optical coherence tomography in living mice and humans

      Speckle-modulating optical coherence tomography in living mice and humans

      Optical coherence tomography (OCT) is a powerful biomedical imaging technology that relies on the coherent detection of backscattered light to image tissue morphology in vivo . As a consequence, OCT is susceptible to coherent noise (speckle noise), which imposes significant limitations on its diagnostic capabilities. Here we show speckle-modulating OCT (SM-OCT), a method based purely on light manipulation that virtually eliminates speckle noise originating from a sample. SM-OCT accomplishes this by creating and averaging an unlimited number of scans with uncorrelated speckle patterns without compromising spatial resolution. Using SM-OCT, we reveal small structures in the tissues of living animals, such as ...

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    22. Atrophy of retinal inner layers is associated with poor vision after endophthalmitis: a spectral domain optical coherence tomography study

      Atrophy of retinal inner layers is associated with poor vision after endophthalmitis: a spectral domain optical coherence tomography study

      urpose To investigate the retinal structural changes in endophthalmitis and their association with visual outcome. Patients and methods Forty-five eyes of 45 patients diagnosed with endophthalmitis were included. Spectral domain optical coherence tomography (SD-OCT) was performed after inflammation was controlled. The relationship between SD-OCT features and best-corrected visual acuity (BCVA) at the last follow-up was analyzed. Results The structural changes included inner segment ellipsoid (ISe) disruption (49 % ), atrophy of retinal inner layers (24 % ), epimacular membrane (24 % ), and macular edema (24 % ). BCVA was worse in patients with ISe disruption (P = 0.005) and retinal inner layers' atrophy (P = 0.004) compared ...

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    23. 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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    24. When pressure meets light: detecting the photoacoustic effect at the origin

      When pressure meets light: detecting the photoacoustic effect at the origin

      Modern optical microscopy1, including confocal microscopy, two-photon microscopy and optical coherence tomography (OCT), has revolutionized life sciences by providing detailed information of biological samples with cellular and subcellular resolutions, and has become an essential tool for biomedical research labs. However, optical microscopy typically has a limited penetration depth of ~1mm in biological tissue due to strong optical scattering23. Moreover, with respective contrast mechanisms, confocal and two-photon microscopy usually rely on fluorescent labeling of the samples and OCT still lacks sensitivity to many biological functions. In contrast, optical-resolution photoacoustic microscopy (OR-PAM) has emerged over the last decade ...

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      Mentions: Duke University
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