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    1. Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Aim To evaluate visual dysfunction and its correlation with structural changes in the retina in patients with Alzheimer's disease (AD). Methods Patients with AD (n = 24) and controls (n = 24) underwent evaluation of visual acuity (VA), color vision (using the Farnsworth and L’Anthony desaturated (D) 15 color tests), and contrast sensitivity vision (CSV; using the Pelli-Robson chart and CSV-1000E test) to measure visual dysfunction. Structural measurements of the retinal nerve fiber layer (RNFL) and macular thickness were obtained using spectral domain-optical coherence tomography (SD-OCT). Results CSV at three of the four spatial frequencies was significantly worse in AD ...

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    2. Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Purpose To report OCT appearance and surgical outcomes of full-thickness macular holes (MHs) accidentally caused by laser devices. Patients and methods This retrospective case series included 11 eyes of 11 patients with laser-induced MHs treated by pars plana vitrectomy, internal limiting membrane (ILM) peeling, and gas or silicone oil tamponade. Evaluations included a full ophthalmic examination, macular spectral-domain optical coherence tomography (SD-OCT), and fundus photography. Main outcome measures is MH closure and final visual acuity; the secondary outcome was the changes of retinal pigment epithelium and photoreceptor layer evaluated by sequential post-operative SD-OCT images. Results Five patients were accidentally injured ...

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    3. Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Accuracy and safety verification of ovarian reserve assessment technique for ovarian tissue transplantation using optical coherence tomography in mice ovary

      Except for histological study, there are currently no suitable techniques available for the detection and identification of primordial follicles in ovary of primary ovarian insufficiency patients who have undetectable AMH levels. Also, the ability to locate and quantify follicles on ovarian cortex strips, without fixation, is valuable for patients who could undergo subsequent successful ovarian tissue transplantation. Although optical coherence tomography (OCT) is a well-established high resolution imaging technique without fixation commonly applied in biomedicine, few reports are available on ovarian tissue imaging. In present study, we established standard OCT follicle images at each developmental stage, including the primordial follicle ...

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    4. Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Design of a k-space spectrometer for ultra-broad waveband spectral domain optical coherence tomography

      Nonlinear sampling of the interferograms in wavenumber ( k ) space degrades the depth-dependent signal sensitivity in conventional spectral domain optical coherence tomography (SD-OCT). Here we report a linear-in-wavenumber ( k -space) spectrometer for an ultra-broad bandwidth (760 nm–920 nm) SD-OCT, whereby a combination of a grating and a prism serves as the dispersion group. Quantitative ray tracing is applied to optimize the linearity and minimize the optical path differences for the dispersed wavenumbers. Zemax simulation is used to fit the point spread functions to the rectangular shape of the pixels of the line-scan camera and to improve the pixel sampling rates ...

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    5. Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Optical coherence tomography evaluation of pulmonary arterial vasculopathy in Systemic Sclerosis

      Our current understanding of the pathophysiology of pulmonary vascular disease is incomplete, since information about alterations of the pulmonary vasculature in pulmonary arterial hypertension (PAH) is primarily provided by autopsy or tissue specimens. The aim of this study was to compare the distal pulmonary vasculature of <2 mm in diameter in Systemic Sclerosis (SSc) patients with (n = 17) and without (n = 5) associated PAH using Optical Coherence Tomography during Right Heart catheterization. SSc-PAH patients showed significant thickening of Intima Media Thickening Area compared to patients without PAH (27 +/− 5.8% vs. 21 +/− 1.4%, p = 0.024). A good haemodynamic ...

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    6. Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Evaluation of choroidal tumors with optical coherence tomography: enhanced depth imaging and OCT-angiography features

      Aim To describe the vascular features of choroidal tumors using enhanced depth imaging (EDI), optical coherence tomography (OCT), and OCT-angiography. Methods In this prospective study, we evaluated 116 Caucasian patients with choroidal tumors (60 eyes with choroidal nevi, 40 with choroidal melanoma, 6 with choroidal hemangioma, 2 with optic disc melanocytoma, 6 with choroidal osteoma, and 2 with retinal metastases). Patients underwent a complete ophthalmic examination including bulbar echography, EDI-OCT, OCT-angiography, and multicolor imaging. Sixteen patients also underwent fluorescein and indocyanine angiography. Results The left eye was more involved than the right eye. The mean tumor thickness was 1.23 ...

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    7. Research Engineer Opening - Probe-based Imaging Diagnostic Tool for In vivo Atherosclerotic Biomarker Detection

      Research Engineer Opening - Probe-based Imaging Diagnostic Tool for In vivo Atherosclerotic Biomarker Detection

      The International Iberian Nanotechnology Laboratory – INL ( http://www.inl.int ), was founded under an international legal framework to perform interdisciplinary research and to deploy and articulate nanotechnology for the benefit of society. INL aims to become the world-wide hub for nanotechnology addressing society's grand challenges with specific emphasis on Aging & Wellbeing, Mobility & Urban Living and a Safe & Secure Society. The work undertaken by our research centre has a significant impact on people's lives and societal benefit. The objective is to ensure that staff is employed on the basis of skills and requirements for the job and that there ...

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    8. Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

      Detailed Vascular Anatomy of the Human Retina by Projection-Resolved Optical Coherence Tomography Angiography

      Optical coherence tomography angiography (OCTA) is a noninvasive method of 3D imaging of the retinal and choroidal circulations. However, vascular depth discrimination is limited by superficial vessels projecting flow signal artifact onto deeper layers. The projection-resolved (PR) OCTA algorithm improves depth resolution by removing projection artifact while retaining in-situ flow signal from real blood vessels in deeper layers. This novel technology allowed us to study the normal retinal vasculature in vivo with better depth resolution than previously possible. Our investigation in normal human volunteers revealed the presence of 2 to 4 distinct vascular plexuses in the retina, depending on location ...

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    9. Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography : Scientific Reports

      Analysis of Craniocardiac Malformations in Xenopus using Optical Coherence Tomography : Scientific Reports

      Birth defects affect 3% of children in the United States. Among the birth defects, congenital heart disease and craniofacial malformations are major causes of mortality and morbidity. Unfortunately, the genetic mechanisms underlying craniocardiac malformations remain largely uncharacterized. To address this, human genomic studies are identifying sequence variations in patients, resulting in numerous candidate genes. However, the molecular mechanisms of pathogenesis for most candidate genes are unknown. Therefore, there is a need for functional analyses in rapid and efficient animal models of human disease. Here, we coupled the frog Xenopus tropicalis with Optical Coherence Tomography (OCT) to create a fast and ...

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    10. Visualizing dynamics of angiogenic sprouting from a three-dimensional microvasculature model using stage-top optical coherence tomography

      Visualizing dynamics of angiogenic sprouting from a three-dimensional microvasculature model using stage-top optical coherence tomography

      Three-dimensional (3D) in vitro microvasculature in a polydimethylsiloxane-based microdevice was developed as a physiologically relevant model of angiogenesis. The angiogenic process is monitored using stage-top optical coherence tomography (OCT). OCT allows non-invasive monitoring of the 3D structures of the prepared host microvasculature and sprouted neovasculature without fluorescence staining. OCT monitoring takes only a few minutes to scan through the several-millimetre scale range, which provides the advantage of rapid observation of living samples. The obtained OCT cross-sectional images capture 3D features of the angiogenic sprouting process and provide information on the dynamics of luminal formation. The stage-top system used in this ...

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    11. Open-source algorithm for automatic choroid segmentation of OCT volume reconstructions

      Open-source algorithm for automatic choroid segmentation of OCT volume reconstructions

      The use of optical coherence tomography (OCT) to study ocular diseases associated with choroidal physiology is sharply limited by the lack of available automated segmentation tools. Current research largely relies on hand-traced, single B-Scan segmentations because commercially available programs require high quality images, and the existing implementations are closed, scarce and not freely available. We developed and implemented a robust algorithm for segmenting and quantifying the choroidal layer from 3-dimensional OCT reconstructions. Here, we describe the algorithm, validate and benchmark the results, and provide an open-source implementation under the General Public License for any researcher to use ( https://www.mathworks ...

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    12. Optical coherence tomography angiography microvascular findings in macular edema due to central and branch retinal vein occlusions

      Optical coherence tomography angiography microvascular findings in macular edema due to central and branch retinal vein occlusions

      The aim of this study was to evaluate retinal and choriocapillaris vessel density using optical coherence tomography angiography (OCTA) in eyes with central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) complicated by macular edema (ME). Sixty eyes of 60 patients with CRVO or BRVO and ME and 40 healthy subjects underwent measurements of superficial and deep foveal and parafoveal vessel density (FVD, PFVD) and choricapillary density using OCTA at baseline and 60 days after intravitreal dexamethasone implant (IVDEX). FVD and PFVD of the superficial plexus were not significantly lower in CRVO group compared to the controls while ...

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    13. Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

      Acoustic micro-tapping for non-contact 4D imaging of tissue elasticity

      Elastography plays a key role in characterizing soft media such as biological tissue. Although this technology has found widespread use in both clinical diagnostics and basic science research, nearly all methods require direct physical contact with the object of interest and can even be invasive. For a number of applications, such as diagnostic measurements on the anterior segment of the eye, physical contact is not desired and may even be prohibited. Here we present a fundamentally new approach to dynamic elastography using non-contact mechanical stimulation of soft media with precise spatial and temporal shaping. We call it acoustic micro-tapping (A ...

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    14. Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

      Anatomically correct visualization of the human upper airway using a high-speed long range optical coherence tomography system with an integrated positioning sensor

      The upper airway is a complex tissue structure that is prone to collapse. Current methods for studying airway obstruction are inadequate in safety, cost, or availability, such as CT or MRI, or only provide localized qualitative information such as flexible endoscopy. Long range optical coherence tomography (OCT) has been used to visualize the human airway in vivo , however the limited imaging range has prevented full delineation of the various shapes and sizes of the lumen. We present a new long range OCT system that integrates high speed imaging with a real-time position tracker to allow for the acquisition of an ...

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    15. High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      High-speed swept source optical coherence Doppler tomography for deep brain microvascular imaging

      Noninvasive microvascular imaging using optical coherence Doppler tomography (ODT) has shown great promise in brain studies; however, high-speed microcirculatory imaging in deep brain remains an open quest. A high-speed 1.3 μm swept-source ODT (SS-ODT) system is reported which was based on a 200 kHz vertical-cavity-surface-emitting laser. Phase errors induced by sweep-trigger desynchronization were effectively reduced by spectral phase encoding and instantaneous correlation among the A-scans. Phantom studies have revealed a significant reduction in phase noise, thus an enhancement of minimally detectable flow down to 268.2 μm/s. Further in vivo validation was performed, in which 3D cerebral-blood-flow (CBF ...

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    16. Comparative study between a spectral domain and a high-speed single-beam swept source OCTA system for identifying choroidal neovascularization in AMD

      Comparative study between a spectral domain and a high-speed single-beam swept source OCTA system for identifying choroidal neovascularization in AMD

      This comparative study between a SD- and SS-OCTA system for visualizing neovascular patterns in AMD, also assessed the influence of cataract on OCTA imaging. 25 eyes with active CNV (AMD) were documented by FA, ICGA and SD-OCT. Two OCTA devices were used: A custom built SS-OCTA (1050 nm, 400,000 A-scans/s, 5 × 5 mm, no image segmentation); AngioVue (OptoVue, CA, USA) SD-OCTA (840 nm, 70.000 A-scans/s, 3 × 3 mm, SSADA technology). Two retina experts graded CNV types and vascular patterns. Cataract influence on OCTA image quality was reported for the superficial retinal plexus (6 eyes). The SS-OCTA ...

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    17. Impact of optical coherence tomography scanning density on quantitative analyses in neovascular age-related macular degeneration

      Impact of optical coherence tomography scanning density on quantitative analyses in neovascular age-related macular degeneration

      Purpose To assess the influence of varying B-scan frame-sampling densities on retinal thickness and volume measurements from spectral domain optical coherence tomography (OCT) in eyes with neovascular age-related macular degeneration (AMD). Methods Volume OCT data (512 × 128 macular cube over 6 × 6   mm) were collected from 39 eyes with neovascular AMD. All 128 B-scans in each image set were manually segmented, allowing quantification of the neurosensory retina, subretinal fluid (SRF), subretinal hyperreflective material (SRHM), and pigment epithelium detachment (PED). Thickness maps were generated for less dense subsets of scans, ranging from every other (64 B-scans) to every 64th (2 B-scans ...

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    18. A view of the current and future role of optical coherence tomography in the management of age-related macular degeneration

      A view of the current and future role of optical coherence tomography in the management of age-related macular degeneration

      Optical coherence tomography (OCT) has become an established diagnostic technology in the clinical management of age-related macular degeneration (AMD). OCT is being used for primary diagnosis, evaluation of therapeutic efficacy, and long-term monitoring. Computer-based advances in image analysis provide complementary imaging tools such as OCT angiography, further novel automated analysis methods as well as feature detection and prediction of prognosis in disease and therapy by machine learning. In early AMD, pathognomonic features such as drusen, pseudodrusen, and abnormalities of the retinal pigment epithelium (RPE) can be imaged in a qualitative and quantitative way to identify early signs of disease activity ...

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    19. Optical computing for optical coherence tomography

      Optical computing for optical coherence tomography

      We propose an all-optical Fourier transformation system for real-time massive data processing in high speed optical coherence tomography (OCT). In the so-called optical computing OCT, fast Fourier transformation (FFT) of A-scan signal is optically processed in real time before being detected by photoelectric detector. Therefore, the processing time for interpolation and FFT in traditional Fourier domain OCT can be dramatically eliminated. A processing rate of 10 mega-A-scans/second was experimentally achieved, which is, to our knowledge, the highest speed for OCT imaging. Due to its fiber based all-optical configuration, this optical computing OCT system is ideal for ultrahigh speed volumetric ...

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    20. 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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    21. Agreement and clinical comparison between a new swept-source optical coherence tomography-based optical biometer and an optical low-coherence reflectometry biometer

      Agreement and clinical comparison between a new swept-source optical coherence tomography-based optical biometer and an optical low-coherence reflectometry biometer

      Purpose To compare measurements taken using a swept-source optical coherence tomography-based optical biometer (IOLmaster 700) and an optical low-coherence reflectometry biometer (Lenstar 900), and to determine the clinical impacts of differences in their measurements on intraocular lens (IOL) power predictions. Methods Eighty eyes of 80 patients scheduled to undergo cataract surgery were examined with both biometers. The measurements made using each device were axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), lens thickness (LT), mean keratometry (MK), white-to-white distance (WTW), and pupil diameter (PD). Holladay 2 and SRK / T formulas were used to calculate IOL power. Differences in ...

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    22. Volumetric Mapping of Barrett’s Esophagus and Dysplasia With en face Optical Coherence Tomography Tethered Capsule

      Volumetric Mapping of Barrett’s Esophagus and Dysplasia With en face Optical Coherence Tomography Tethered Capsule

      To the Editor: Dysplasia in Barrett’s Esophagus (BE) is patchy ( 1 ) and sometimes missed by random biopsies. Optical coherence tomography (OCT) can image large areas of the esophagus; however, slow imaging speeds in earlier studies limited visualization to cross-sections. Cross-sectional OCT detected high-grade dysplasia with sensitivity / specificity of ~80 % ( 2 , 3 ). Tethered OCT capsules were demonstrated for cross-sectional imaging in unsedated screening to detect BE ( 4 , 5 ). Our group recently developed ultrahigh-speed OCT for en face and angiographic imaging, using micromotor probes in patients ( 6 , 7 ) and large field-of-view tethered capsule devices in swine ( 8 ). Narrow-band imaging (NBI) visualizes ...

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    23. In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      In Vivo Near Infrared Virtual Intraoperative Surgical Photoacoustic Optical Coherence Tomography

      Since its first implementation in otolaryngological surgery nearly a century ago, the surgical microscope has improved the accuracy and the safety of microsurgeries. However, the microscope shows only a magnified surface view of the surgical region. To overcome this limitation, either optical coherence tomography (OCT) or photoacoustic microscopy (PAM) has been independently combined with conventional surgical microscope. Herein, we present a near-infrared virtual intraoperative photoacoustic optical coherence tomography (NIR-VISPAOCT) system that combines both PAM and OCT with a conventional surgical microscope. Using optical scattering and absorption, the NIR-VISPAOCT system simultaneously provides surgeons with real-time comprehensive biological information such as tumor ...

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    1-24 of 287 1 2 3 4 ... 10 11 12 »
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