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    1. Optical coherence tomography angiography as a novel approach to contactless evaluation of sublingual microcirculation: A proof of principle study

      Optical coherence tomography angiography as a novel approach to contactless evaluation of sublingual microcirculation: A proof of principle study

      Microcirculatory disorders are crucial in pathophysiology of organ dysfunction in critical illness. Evaluation of sublingual microcirculation is not routinely conducted in daily practice due to time-consuming analysis and susceptibility to artifacts. We investigated the suitability of optical coherence tomography angiography (OCTA) for contactless evaluation of sublingual microcirculation. Sublingual microcirculation was imaged in 10 healthy volunteers, using an OCTA device and an incident dark field (IDF) illumination microscopy (current gold standard). OCTA images were analyzed with regard to flow density and perfused vessel density (PVD byOCTA ). IDF videos were analyzed following current recommendations. Flow density was automatically extracted from OCTA images ...

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    2. Retinal neurodegeneration in patients with end-stage renal disease assessed by spectral-domain optical coherence tomography

      Retinal neurodegeneration in patients with end-stage renal disease assessed by spectral-domain optical coherence tomography

      Spectral-domain optical coherence tomography (SD-OCT) represents a reliable tool for retinal layer volume and thickness measurement. The aim of this study was to evaluate retinal changes indicating neurodegenerative processes in patients with end-stage renal disease (ESRD) compared to healthy controls. This was a cross-sectional, single-center study comprising 32 ESRD patients and 38 controls. Sectoral retinal nerve fiber layer (RNFL) thickness and retinal layer volumes were obtained by SD-OCT. Age- and gender-adjusted retinal layer volumes such as total retinal volume (p = 0.037), ganglion cell layer volume (GCL, p = 0.003), ganglion cell layer – inner plexiform layer volume (GCL-IPL, p = 0 ...

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    3. Comparison of composite and segmental methods for acquiring optical axial length with swept-source optical coherence tomography

      Comparison of composite and segmental methods for acquiring optical axial length with swept-source optical coherence tomography

      This study compared the optical axial length (AL) obtained by composite and segmental methods using swept-source optical coherence tomography (SS-OCT) devices, and demonstrated its effects on the post-operative refractive errors (RE) one month after cataract surgery. Conventional AL measured with the composite method used the mean refractive index. The segmented-AL method used individual refractive indices for each ocular medium. The composite AL (24.52 ± 2.03 mm) was significantly longer ( P  < 0.001) than the segmented AL (24.49 ± 1.97 mm) among a total of 374 eyes of 374 patients. Bland–Altman analysis revealed a negative proportional bias for ...

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      Mentions: Osaka University
    4. Cutaneous optical coherence tomography for longitudinal volumetric assessment of intradermal volumes in a mouse model

      Cutaneous optical coherence tomography for longitudinal volumetric assessment of intradermal volumes in a mouse model

      Clinical evaluation of skin lesions requires precise and reproducible technologies for their qualitative and quantitative assessment. In this study, we investigate the applicability of a custom-built dermatologic OCT system for longitudinal assessment of intradermal volumes in a mouse model. The OCT, based on an akinetic swept laser working at 1310 nm was employed for visualization and quantification of intradermal deposits of three different hyaluronic acid-based hydrogel formulations – one commercial and two test substances. Hydrogels were applied in 22 BALB/c mice, and measurements were performed over a six-month time period. All hydrogels increased in volume within the first weeks and ...

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    5. Optical coherence tomography angiography (OCTA) applications in ocular oncology

      Optical coherence tomography angiography (OCTA) applications in ocular oncology

      Optical coherence tomography angiography (OCTA) is a revolutionary method in the visualization of the vascular system in different retinal and choroidal layers. During the last 4 years since the commercial availability of different OCTA devices, attempts have been made to utilize this technology in various aspects of ocular oncology from the differentiation of benign and malignant lesions to assisting in evaluation of post-treatment complications, such as radiation retinopathy. However, current OCTA technology is restricted by various artefacts and inherent limitations, some of which are more pronounced in the presence of elevated tumoural lesions. Imminent advancements in OCTA systems and image ...

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    6. Diagnostic ability of vessel density measured by spectral-domain optical coherence tomography angiography for glaucoma in patients with high myopia

      Diagnostic ability of vessel density measured by spectral-domain optical coherence tomography angiography for glaucoma in patients with high myopia

      Although early glaucoma detection is important to prevent visual loss due to disease progression, its clinical diagnosis in highly myopic eyes is still difficult. Many studies using optical coherence tomography (OCT) angiography (OCTA) reported decreased vessel density (VD) in glaucomatous eyes compared to normal eyes. We evaluated the diagnostic ability of peripapillary VD and macular VD measured by OCTA, comparing them with conventional valuables such as peripapillary retinal nerve fibre layer (RNFL) thickness and macular ganglion cell-inner plexiform layer (GCIPL) thickness measured by OCT. We also calculated the average VD ratio (VDR) (average outer macular VD/average inner macular VD ...

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    7. Alterations in optical coherence tomography angiography findings in patients with high myopia

      Alterations in optical coherence tomography angiography findings in patients with high myopia

      Article Published: 24 February 2020 Alterations in optical coherence tomography angiography findings in patients with high myopia Turgay Ucak , Erel Icel , Hayati Yilmaz , Yucel Karakurt , Gamze Tasli , Adem Ugurlu & Erdinc Bozkurt Eye ( 2020 ) Cite this article 3 Altmetric Metrics details Abstract Purpose The aim of this study was to determine the macular changes using optical coherence tomography (OCT) and OCT-angiography (OCT-A) in eyes with high myopia. Determining the alterations in vascular structures can provide a clearer understanding of the pathophysiological mechanisms of this disease and help define new treatment options and preventive measures. Materials and methods Ninety-two patients with high ...

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    8. Quantifying lipofuscin in retinal pigment epithelium in vivo by visible-light optical coherence tomography-based multimodal imaging

      Quantifying lipofuscin in retinal pigment epithelium in vivo by visible-light optical coherence tomography-based multimodal imaging

      Lipofuscin in the retinal pigment epithelium (RPE) is the major source of fundus autofluorescence (FAF). A technical challenge to accurately quantify the FAF intensities, thus the lipofuscin concentration, is to compensate the light attenuation of RPE melanin. We developed the VIS-OCT-FAF technology to accomplish optical coherence tomography (OCT) and FAF simultaneously with a single broadband visible light source. We demonstrated that light attenuation by RPE melanin can be assessed and corrected using the depth-resolved OCT signals. FAF images from albino and pigmented rats showed that without compensation, FAF signals from pigmented rats are lower than that from albinos. After compensation ...

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    9. MultiColor imaging to detect different subtypes of retinal microaneurysms in diabetic retinopathy

      MultiColor imaging to detect different subtypes of retinal microaneurysms in diabetic retinopathy

      Background Retinal microaneurysms (MAs) are among the earliest signs of diabetic retinopathy (DR) and are typically detected by fluorescein angiography (FA). Confocal MultiColor is a noninvasive-imaging technique able to analyze different retinal features by capturing three simultaneous reflectance images. The main aim of the present study was to characterize morphological features of MAs by means of MultiColor images and to compare these with spectral domain optical coherence tomography (SD-OCT) and FA findings. Methods A cross-sectional, observational study setting was chosen. Multimodal imaging included MultiColor, SD-OCT and FA images. We performed a qualitative analysis in order to assess the relationship between ...

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    10. Fully automated plaque characterization in intravascular OCT images using hybrid convolutional and lumen morphology features

      Fully automated plaque characterization in intravascular OCT images using hybrid convolutional and lumen morphology features

      For intravascular OCT (IVOCT) images, we developed an automated atherosclerotic plaque characterization method that used a hybrid learning approach, which combined deep-learning convolutional and hand-crafted, lumen morphological features. Processing was done on innate A-line units with labels fibrolipidic (fibrous tissue followed by lipidous tissue), fibrocalcific (fibrous tissue followed by calcification), or other. We trained/tested on an expansive data set (6,556 images), and performed an active learning, relabeling step to improve noisy ground truth labels. Conditional random field was an important post-processing step to reduce classification errors. Sensitivities/specificities were 84.8%/97.8% and 91.4%/95.7 ...

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    11. Foveal Microvascular Structures in Eyes with Silicone Oil Tamponade for Rhegmatogenous Retinal Detachment: A Swept-source Optical Coherence Tomography Angiography Study

      Foveal Microvascular Structures in Eyes with Silicone Oil Tamponade for Rhegmatogenous Retinal Detachment: A Swept-source Optical Coherence Tomography Angiography Study

      Silicone oil (SO) is widely used as a long-term intravitreal tamponading agent for rhegmatogenous retinal detachment (RRD) repair. This study investigated the structural changes of the foveal microvasculature using optical coherence tomography angiography (OCTA) in patients with RRD treated with vitrectomy and SO tamponade. Thirty-eight patients with unilateral RRD who were treated with vitrectomy and SO tamponade and were followed up for ≥3 months after SO removal were included. En face OCTA images were obtained and foveal avascular zone (FAZ) area and vascular density (VD) were compared between study eyes and unaffected contralateral eyes. The FAZ area in deep capillary ...

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    12. Widefield topographical analysis of the retinal perfusion and neuroretinal thickness in healthy eyes: a pilot study

      Widefield topographical analysis of the retinal perfusion and neuroretinal thickness in healthy eyes: a pilot study

      Purpose In this pilot study we reported variation of superficial (SCP) and deep (DCP) capillary plexuses flow in macular and near/mid periphery regions in healthy subjects using widefield swept source-optical coherence tomography angiography (SS-OCTA). Methods In this prospective, cross-sectional study, enroled subjects were imaged with an SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). OCTA scans were taken in primary and extremes of gaze and a montage was automatically created. Quantitative analysis was performed in the macular and peripheral regions. In addition, SCP and DCP variables were further investigated in distinct fields within these three ...

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    13. Endovascular procedures cause transient endothelial injury but do not disrupt mature neointima in Drug Eluting Stents

      Endovascular procedures cause transient endothelial injury but do not disrupt mature neointima in Drug Eluting Stents

      Extensive application of coronary intravascular procedures has led to the increased need of understanding the injury inflicted to the coronary arterial wall. We aimed to investigate acute and prolonged coronary endothelial injury as a result of guidewire use, repeated intravascular imaging and stenting. These interventions were performed in swine (N = 37) and injury was assessed per coronary segment (n = 81) using an Evans Blue dye-exclusion-test. Scanning electron microscopy and light microscopy were then used to visualize the extent and nature of acute (<4 hours) and prolonged (5 days) endothelial injury. Guidewire and imaging injury was mainly associated with denudation and ...

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    14. Analysis of Optic Chiasmal Compression Caused by Brain Tumors Using Optical Coherence Tomography Angiography

      Analysis of Optic Chiasmal Compression Caused by Brain Tumors Using Optical Coherence Tomography Angiography

      Article Open Access Published: 07 February 2020 Analysis of Optic Chiasmal Compression Caused by Brain Tumors Using Optical Coherence Tomography Angiography Ga-In Lee , Kyung-Ah Park , Sei Yeul Oh & Doo-Sik Kong Scientific Reports volume 10 , Article number: 2088 ( 2020 ) Cite this article 49 Accesses 1 Altmetric Metrics details Abstract We have quantitatively evaluated the macular and peripapillary microvascular changes in eyes with chiasmal compression caused by brain tumors compared with healthy control eyes using optical coherence tomography angiography (OCT-A) and correlated them with other ocular parameters. This cross-sectional study involved the analysis of 36 eyes of 36 patients with chiasmal compression ...

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    15. Application and Evaluation of Highly Automated Software for Comprehensive Stent Analysis in Intravascular Optical Coherence Tomography

      Application and Evaluation of Highly Automated Software for Comprehensive Stent Analysis in Intravascular Optical Coherence Tomography

      Intravascular optical coherence tomography (IVOCT) is used to assess stent tissue coverage and malapposition in stent evaluation trials. We developed the OCT Image Visualization and Analysis Toolkit for Stent (OCTivat-Stent), for highly automated analysis of IVOCT pullbacks. Algorithms automatically detected the guidewire, lumen boundary, and stent struts; determined the presence of tissue coverage for each strut; and estimated the stent contour for comparison of stent and lumen area. Strut-level tissue thickness, tissue coverage area, and malapposition area were automatically quantified. The software was used to analyze 292 stent pullbacks. The concordance-correlation-coefficients of automatically measured stent and lumen areas and independent ...

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    16. Angular compounding for speckle reduction in optical coherence tomography using geometric image registration algorithm and digital focusing

      Angular compounding for speckle reduction in optical coherence tomography using geometric image registration algorithm and digital focusing

      Optical coherence tomography (OCT) suffers from speckle noise due to the high spatial coherence of the utilized light source, leading to significant reductions in image quality and diagnostic capabilities. In the past, angular compounding techniques have been applied to suppress speckle noise. However, existing image registration methods usually guarantee pure angular compounding only within a relatively small field of view in the focal region, but produce spatial averaging in the other regions, resulting in resolution loss and image blur. This work develops an image registration model to correctly localize the real-space location of every pixel in an OCT image, for ...

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    17. Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

      Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

      Prolonged microgravity exposure during long-duration spaceflight (LDSF) produces unusual physiologic and pathologic neuro-ophthalmic findings in astronauts. These microgravity associated findings collectively define the “Spaceflight Associated Neuro-ocular Syndrome” (SANS). We compare and contrast prior published work on SANS by the National Aeronautics and Space Administration’s (NASA) Space Medicine Operations Division with retrospective and prospective studies from other research groups. In this manuscript, we update and review the clinical manifestations of SANS including: unilateral and bilateral optic disc edema, globe flattening, choroidal and retinal folds, hyperopic refractive error shifts, and focal areas of ischemic retina (i.e., cotton wool spots). We ...

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    18. Choroidoscleral Interface Irregularity Index: A novel optical coherence tomography-based parameter in patients with epiretinal membrane

      Choroidoscleral Interface Irregularity Index: A novel optical coherence tomography-based parameter in patients with epiretinal membrane

      This study aimed to assess the regularity of the choroidoscleral interface (CSI) using a novel parameter, CSI irregularity index, before and after epiretinal membrane (ERM) surgery. This study included 36 patients with idiopathic ERM who underwent pars plana vitrectomy and ERM removal. All subjects underwent ocular examinations at baseline and at 1, 2, 4, and 6 months after surgery. The regular contour of the CSI was found in 14 patients (38.9%); mean CSI irregularity index was 14.84 ± 11.01 in this group. The irregular contour of the CSI was found in 22 patients (61.1%); mean CSI irregularity ...

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    19. Evaluation of macular thickness and volume tested by optical coherence tomography as biomarkers for Alzheimer’s disease in a memory clinic

      Evaluation of macular thickness and volume tested by optical coherence tomography as biomarkers for Alzheimer’s disease in a memory clinic

      Building on previous studies that report thinning of the macula in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) patients, the use of optical coherence tomography (OCT) has been proposed as a potential biomarker for AD. However, other studies contradict these results. A total of 930 participants (414 cognitively healthy people, 192 with probable amnestic MCI, and 324 probable AD patients) from a memory clinic were consecutively included in this study and underwent a spectral domain OCT scan (Maestro, Topcon) to assess total macular volume and thickness. Macular width measurements were also taken in several subregions (central, inner, and ...

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    20. Integrated terahertz radar based on leaky-wave coherence tomography

      Integrated terahertz radar based on leaky-wave coherence tomography

      Terahertz wave radar offers a higher resolution and smaller aperture compared with microwave radar. However, despite the emergence of terahertz sources and detectors suitable for radar front ends, the integration of a phased-array radar system remains challenging due to the lack of phase shifters and circulators, the basic components for beam steering and input–output isolation. Here we show that leaky-wave coherence tomography, which can integrate a terahertz radar system using a pair of reverse-connected leaky-wave antennas, can be used to implement beam steering and homodyne detection in one package. Our approach can detect direction and range without using phase ...

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