1. Articles from amani a. fawzi

    1-24 of 58 1 2 3 »
    1. Perspectives on diabetic retinopathy from advanced retinal vascular imaging

      Perspectives on diabetic retinopathy from advanced retinal vascular imaging

      Diabetic retinopathy (DR) is a microvascular complication of diabetes and the most common cause of acquired vision loss in adults worldwide. DR is associated with long-term chronic hyperglycaemia and its detrimental effects on the neurovascular structure and function of the retina. Direct imaging of the retinal vasculature and staging of DR has been traditionally based on fundoscopy and fluorescein angiography, which provide only 2D views of the retina, and in the case of fluorescein angiography, requires an invasive dye injection. In contrast, advanced retinal imaging modalities like optical coherence tomography angiography (OCTA) and adaptive optics (AO) are non-invasive and provide ...

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    2. New Method for Reducing Artifactual Flow Deficits Caused by Compensation Techniques in the Choriocapillaris with Optical Coherence Tomography Angiography

      New Method for Reducing Artifactual Flow Deficits Caused by Compensation Techniques in the Choriocapillaris with Optical Coherence Tomography Angiography

      Purpose: To mitigate artifactual choriocapillaris flow deficits in optical coherence tomography angiography (OCTA), which are a side effect of inverse structural OCT compensation. Methods: In a modified algorithm, we set pixels in the original structural OCT that were greater than one standard deviation above the mean intensity (hyperreflective regions) to the mean pixel intensity of the image to remove hyporeflective regions in the inverse slab. We compared this algorithm to the original using flow deficit density (FDD) and multiscale structural similarity index (MS-SSIM) obtained from three distinct thresholding methods (local Phansalkar, global MinError(I) and global Li). Results: We included ...

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    3. Macrophage-Like Cell Density Is Increased in Proliferative Diabetic Retinopathy Characterized by Optical Coherence Tomography Angiography

      Macrophage-Like Cell Density Is Increased in Proliferative Diabetic Retinopathy Characterized by Optical Coherence Tomography Angiography

      Purpose: To quantitatively characterize macrophage-like cells (MLCs) at the vitreoretinal interface in different severity stages of diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA). Methods: The study included 72 eyes of 72 subjects: 18 healthy controls, 22 diabetes mellitus (DM) without DR, 17 nonproliferative DR (NPDR), and 15 proliferative DR (PDR). We obtained repeated (average, 6.5; range, 3-10) macular OCTA scans for each eye. We registered and averaged the 3-µm OCT slab above the vitreoretinal interface to visualize MLCs. Using a semiautomated method, we binarized and quantified MLCs and compared MLC densities among groups. We also evaluated ...

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    4. Assessment of retinal microvascular health by optical coherence tomography angiography among persons with HIV

      Assessment of retinal microvascular health by optical coherence tomography angiography among persons with HIV

      Microvasculopathy may link HIV-related chronic inflammation and premature multimorbidity. In this proof-of-concept study, we used optical coherence tomography angiography (OCTA) to evaluate the retina as a convenient assessment of microvascular health among persons with HIV (PWH) undergoing surveillance ophthalmic care at Emory from 2018—2021. Among patients with longstanding HIV, OCTA identified microvascular abnormalities even among eyes without clinical retinal pathology. Retinovascular evaluation by OCTA is a feasible, non-invasive technique for assessing microvasculopathy among PWH.

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      Mentions: Emory University
    5. Reversed Neurovascular Coupling on Optical Coherence Tomography Angiography Is the Earliest Detectable Abnormality before Clinical Diabetic Retinopathy

      Reversed Neurovascular Coupling on Optical Coherence Tomography Angiography Is the Earliest Detectable Abnormality before Clinical Diabetic Retinopathy

      Diabetic retinopathy (DR) has traditionally been viewed as either a microvasculopathy or a neuropathy, though neurovascular coupling deficits have also been reported and could potentially be the earliest derangement in DR. To better understand neurovascular coupling in the diabetic retina, we investigated retinal hemodynamics by optical coherence tomography angiography (OCTA) in individuals with diabetes mellitus (DM) but without DR (DM no DR) and mild non-proliferative DR (mild NPDR) compared to healthy eyes. Using an experimental design to monitor the capillary responses during transition from dark adaptation to light, we examined 19 healthy, 14 DM no DR and 11 mild NPDR ...

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    6. Superficial capillary perfusion on optical coherence tomography angiography differentiates moderate and severe nonproliferative diabetic retinopathy

      Superficial capillary perfusion on optical coherence tomography angiography differentiates moderate and severe nonproliferative diabetic retinopathy

      Purpose To identify objective optical coherence tomography angiography (OCTA) parameters that characterize the spectrum of non-proliferative diabetic retinopathy (NPDR), especially those that distinguish moderate from severe NPDR. Methods Sixty eyes of 60 patients with treatment-naïve NPDR (mild: 21, moderate: 21, severe: 18), 23 eyes with diabetes and no retinopathy, and 24 healthy control eyes were enrolled. OCTA slabs were segmented into superficial (SCP), middle (MCP), and deep capillary plexus (DCP) and thresholded by a new method based on DCP skeletonized vessel length. The foveal avascular zone (FAZ) area, parafoveal vessel density (VD), and adjusted flow index (AFI) from all ...

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    7. Acute Hyperglycemia Reverses Neurovascular Coupling During Dark to Light Adaptation in Healthy Subjects on Optical Coherence Tomography Angiography

      Acute Hyperglycemia Reverses Neurovascular Coupling During Dark to Light Adaptation in Healthy Subjects on Optical Coherence Tomography Angiography

      Purpose : To test the hypothesis that hyperglycemia perturbs neurovascular\ coupling and compromises retinal vascular response during transition from dark to light in healthy subjects using optical coherence tomography angiography (OCTA). Methods : Ten eyes of 10 healthy subjects were tested, first during fasting and then after receiving a 75-g oral glucose solution. In both sessions, OCTA imaging was done in the dark-adapted state and at 50 seconds, 2 minutes, 5 minutes, and 15 minutes of ambient light. Parafoveal vessel density (VD) and adjusted flow index (AFI) were calculated for the superficial capillary plexus (SCP), middle capillary plexus (MCP), and deep capillary ...

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    8. Caffeine Delays Retinal Neurovascular Coupling during Dark to Light Adaptation in Healthy Eyes Revealed by Optical Coherence Tomography Angiography

      Caffeine Delays Retinal Neurovascular Coupling during Dark to Light Adaptation in Healthy Eyes Revealed by Optical Coherence Tomography Angiography

      Purpose : The purpose of this study was to investigate the acute effects of caffeine on retinal hemodynamics during dark to light adaptation using optical coherence tomography angiography (OCTA). Methods : Thirteen healthy individuals (13 eyes) underwent OCTA imaging after dark adaptation and at repeated intervals during the transition to ambient light in two imaging sessions: control and after ingesting 200 mg of caffeine. We analyzed the parafoveal vessel density (VD) and adjusted flow index (AFI) of the superficial capillary plexus (SCP), middle capillary plexus (MCP), and deep capillary plexus (DCP), as well as the vessel length density (VLD) of the SCP ...

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    9. Optical coherence tomography angiography reveals progressive worsening of retinal vascular geometry in diabetic retinopathy and improved geometry after panretinal photocoagulation

      Optical coherence tomography angiography reveals progressive worsening of retinal vascular geometry in diabetic retinopathy and improved geometry after panretinal photocoagulation

      Purpose To quantify vessel tortuosity and fractal dimension of the superficial capillary plexus (SCP) of the macula in different stages of diabetic retinopathy (DR), and following panretinal photocoagulation (PRP) using optical coherence tomography angiography (OCTA). Methods 75 eyes of 75 subjects were divided into five groups; healthy controls, diabetes with no clinical DR, non-proliferative diabetic retinopathy (NPDR), proliferative diabetic retinopathy (PDR) and patients who received PRP for PDR (PDR+PRP).For vessel tortuosity, SCP slabs from 3x3 mm macular OCTA scans were processed using imageJ (NIH, USA), where large perifoveal vessels were traced and their length was measured with tortuosity ...

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    10. Retinal Imaging in Alzheimer’s Disease: In Search of the Holy Grail

      Retinal Imaging in Alzheimer’s Disease: In Search of the Holy Grail

      Alzheimer’s disease (AD) is the most common cause of dementia, accounting for 60% to 80% of cases worldwide. 1 The pathologic hallmark of the disease is the accumulation of extracellular beta amyloid plaques and intracellular tau filaments, ultimately leading to neuronal death. The current approved treatments slow down the progression of the disease, but do not stop the neurodegeneration caused by it. The past 2 decades have witnessed repeated failures of clinical trials using disease-modifying therapies targeting amyloid. 2 These failures have prompted a major rethinking of the approach, with the general consensus being that potential treatments would work ...

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    11. Parafoveal vessel changes in primary open-angle glaucoma and normal-tension glaucoma using optical coherence tomography angiography

      Parafoveal vessel changes in primary open-angle glaucoma and normal-tension glaucoma using optical coherence tomography angiography

      Purpose: To evaluate parafoveal and peripapillary perfusion in healthy, glaucoma suspect, normal-tension glaucoma, and primary open-angle glaucoma subjects. Patients and methods: This was a retrospective cross-sectional study with optical coherence tomography angiography imaging with RTVue XR Avanti (Optovue, Inc., Fremont, CA) of 56 eyes (14 healthy, 14 glaucoma suspect, 16 normal-tension glaucoma, and 12 primary open-angle glaucoma) at a tertiary academic referral center. Parafoveal and peripapillary superficial vessel density and parafoveal superficial retinal thickness were the main parameters of interest. Area under receiver operating characteristic curves were calculated. Results: There were significant decreases in parafoveal superficial vessel density in primary ...

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    12. Speckle reduction in visible-light optical coherence tomography using scan modulation

      Speckle reduction in visible-light optical coherence tomography using scan modulation

      We present a technique to reduce speckle in visible-light optical coherence tomography (vis-OCT) that preserves fine structural details and is robust against sample motion. Specifically, we locally modulate B-scans orthogonally to their axis of acquisition. Such modulation enables acquisition of uncorrelated speckle patterns from similar anatomical locations, which can be averaged to reduce speckle. To verify the effectiveness of speckle reduction, we performed in-vivo retinal imaging using modulated raster and circular scans in both mice and humans. We compared speckle-reduced vis-OCT images with the images acquired with unmodulated B-scans from the same anatomical locations. We compared contrast-to-noise ratio (CNR) and ...

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    13. Exploring the relationship between collaterals and vessel density in retinal vein occlusions using optical coherence tomography angiography

      Exploring the relationship between collaterals and vessel density in retinal vein occlusions using optical coherence tomography angiography

      Purpose To characterize the types of collaterals in eyes with retinal vein occlusion (RVO) and further investigate their correlations with vessel densities of the superficial (SCP) and the deep capillary plexus (DCP) using optical coherence tomography angiography (OCTA). Methods This cross-sectional study included 25 eyes of 23 patients with RVO. 3 x 3 mm 2 OCTA macular scans were used to quantify the parafoveal vessel density (VD) of the SCP and DCP, and to classify the collaterals into one of four types (true superficial, true deep, superficial diving, and foveal collateral). Generalized estimating equation (GEE) regression analysis was performed to ...

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    14. Designing visible-light optical coherence tomography towards clinics

      Designing visible-light optical coherence tomography towards clinics

      Background: The capabilities of visible-light optical coherence tomography (vis-OCT) in noninvasive anatomical and functional retinal imaging have been demonstrated by multiple groups in both rodents and healthy human subjects. Translating laboratory prototypes to an integrated clinical-environment-friendly system is required to explore the full potential of vis-OCT in disease management. Methods: We developed and optimized a portable vis-OCT system for human retinal imaging in clinical settings. We acquired raster- and circular-scan images from both healthy and diseased human eyes. Results: The new vis-OCT provided high-quality retinal images of both subjects without any known eye diseases and patients with various retinal diseases ...

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    15. Projection resolved optical coherence tomography angiography to distinguish flow signal in retinal angiomatous proliferation from flow artifact

      Projection resolved optical coherence tomography angiography to distinguish flow signal in retinal angiomatous proliferation from flow artifact

      Purpose To investigate whether hyperreflective foci (HRF) exhibit flow projection artifact on OCTA, and study the efficacy of commercial projection artifact removal software (PAR-OCTA, Optovue, Inc), and a custom projection resolved OCTA (PR-OCTA) in distinguishing artifacts from true flow in retinal angiomatous proliferation (RAP). Methods The study included five eyes with HRF representing pigment migration in dry age-related macular degeneration (AMD), five eyes with leaking treatment- naïve RAP, and ten eyes with diabetic hard exudates. We examined flow signal on OCTA cross-sections using PAR, and performed PR-OCTA to study the effect of increasingly stringent projection removal thresholds. Flow signal ...

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    16. Improved Macular Capillary Flow On Optical Coherence Tomography Angiography After Panretinal Photocoagulation For Proliferative Diabetic Retinopathy

      Improved Macular Capillary Flow On Optical Coherence Tomography Angiography After Panretinal Photocoagulation For Proliferative Diabetic Retinopathy

      Purpose To evaluate the macular microvascular changes in eyes with proliferative diabetic retinopathy (PDR) following panretinal photocoagulation (PRP) Methods Using OCT angiography, we prospectively studied 10 eyes of 10 subjects with high risk PDR immediately before, 1 month and 3-6 months following PRP, using 3x3mm OCTA scan at each visit. The following parameters were calculated for the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP): parafoveal vessel density, adjusted flow index (AFI) and percent area of non-perfusion (PAN). Parafoveal SCP vessel length density (VLD) was also evaluated. We performed univariate and multivariable statistics, adjusting for age and signal strength ...

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    17. Exploring the association of collaterals and vessel density using optical coherence tomography angiography in retinal vein occlusions

      Exploring the association of collaterals and vessel density using optical coherence tomography angiography in retinal vein occlusions

      Purpose: Using optical coherence tomography angiography (OCTA) to characterize the types of collaterals in eyes with retinal vein occlusion (RVO) and further investigate their correlations with vessel densities of the superficial (SCP) and the deep capillary plexus (DCP). Methods: This cross-sectional study included 25 eyes of 23 patients with RVO. 3 x 3 mm2 OCTA macular scans were used to quantify the parafoveal vessel density (VD) of the SCP and DCP, and to classify the collaterals into one of four types (true superficial, true deep, superficial diving, and foveal collateral). Poisson regression model was used to identify significant associations between ...

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    18. An overview of optical coherence tomography angiography and the posterior pole

      An overview of optical coherence tomography angiography and the posterior pole

      Optical coherence tomography angiography is a relatively new, noninvasive technology that has revolutionized imaging of the retinal and choroidal microvasculature. This technology is based on the detection of movement or changes that represent moving red cells in sequential optical coherence tomography scans. As with other established imaging technologies, it has unique benefits as well as certain disadvantages, which include a limited field of view and vulnerability to imaging artifacts. However, software and hardware improvements are continually evolving to mitigate these limitations. Optical coherence tomography angiography has been used to gain a better understanding of microvascular changes across a spectrum of ...

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    19. Parafoveal vessel loss and correlation between peripapillary vessel density and cognitive performance in amnestic mild cognitive impairment and early Alzheimer’s Disease on optical coherence tomography angiography

      Parafoveal vessel loss and correlation between peripapillary vessel density and cognitive performance in amnestic mild cognitive impairment and early Alzheimer’s Disease on optical coherence tomography angiography

      Purpose Patients with Alzheimer’s Disease (AD) exhibit decreased retinal blood flow and vessel density (VD). However, it is not known whether these changes are also present in individuals with early AD (eAD) or amnestic type mild cognitive impairment (aMCI), an enriched pre-AD population with a higher risk for progressing to dementia. We performed a prospective case-control clinical study to investigate whether optical coherence tomography angiography (OCTA) parameters in the macula and disc are altered in those with aMCI and eAD. Methods This is a single center study of 32 participants. Individuals with aMCI/eAD (n = 16) were 1:1 ...

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    20. Hemodynamic Response of the Three Macular Capillary Plexuses in Dark Adaptation and Flicker Stimulation Using Optical Coherence Tomography Angiography

      Hemodynamic Response of the Three Macular Capillary Plexuses in Dark Adaptation and Flicker Stimulation Using Optical Coherence Tomography Angiography

      Purpose : To assess retinal microvascular reactivity during dark adaptation and the transition to ambient light and after flicker stimulation using optical coherence tomography angiography (OCTA). Methods : Fifteen eyes of 15 healthy participants were dark adapted for 45 minutes followed by OCTA imaging in the dark-adapted state. After 5 minutes of normal lighting, subjects underwent OCTA imaging. Participants were then subjected to a flashing light-emitting diode (LED) light and repeat OCTA. Parafoveal vessel density and adjusted flow index (AFI) were calculated for superficial (SCP), middle (MCP), and deep capillary plexuses (DCP), and then compared between conditions after adjusting for age, refractive ...

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    21. Earliest Evidence of Preclinical Diabetic Retinopathy Revealed using OCT Angiography (OCTA) Perfused Capillary Density

      Earliest Evidence of Preclinical Diabetic Retinopathy Revealed using OCT Angiography (OCTA) Perfused Capillary Density

      Purpose To compare perfused capillary density (PCD) in diabetic patients and healthy controls using optical coherence tomography angiography (OCTA). Methods Forty controls, 36 diabetics without clinical retinopathy (NoDR), 38 with nonproliferative retinopathy (NPDR), and 38 with proliferative retinopathy (PDR) were imaged using SD-OCT. A 3x3 mm full-thickness parafoveal OCTA scan was obtained from each participant. Following manual delineation of the foveal avascular zone (FAZ), FAZ area, perimeter, and acircularity index were determined. Seven consecutive equidistant 200-μm-wide annular segments were drawn at increasing eccentricities from the FAZ margin. Annular PCD (%) was defined as perfused capillary area divided by the corresponding ...

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    22. Vertical Hyperreflective Lesions on Optical Coherence Tomography in Vitreoretinal Lymphoma

      Vertical Hyperreflective Lesions on Optical Coherence Tomography in Vitreoretinal Lymphoma

      Importance Vitreoretinal lymphoma is a diagnostic challenge and the pathophysiology is still unclear. Objective To describe an imaging finding seen on optical coherence tomography (OCT) of patients with vitreoretinal lymphoma. Design, Setting, and Participants This case series study was a retrospective medical record review of patients who received a diagnosis of vitreoretinal lymphoma at the Department of Ophthalmology at Northwestern University between July 2014 and January 2016. Main Outcomes and Measures Optical coherence tomography findings in vitreoretinal lymphoma. Results We identified 7 patients (4 women [57.1%]; mean [range] age, 62.4 [45-75] years; 12 eyes) with intraocular lymphoma involving ...

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    23. Statistical Model of Optical Coherence Tomography Angiography Parameters That Correlate With Severity of Diabetic Retinopathy

      Statistical Model of Optical Coherence Tomography Angiography Parameters That Correlate With Severity of Diabetic Retinopathy

      Purpose : To determine whether combining quantitative optical coherence tomography angiography (OCTA) parameters can achieve high sensitivity and specificity to distinguish eyes with nonproliferative diabetic retinopathy (NPDR) from those with proliferative diabetic retinopathy (PDR) as well as eyes with diabetes and no DR (NoDR) from those with clinical DR (any DR). Methods : This cross-sectional study included 28 eyes (17 patients) with NoDR, 54 eyes (34 patients) with NPDR, and 56 eyes (36 patients) with PDR. OCTA images were processed to quantify the foveal avascular zone (FAZ) area, acircularity, vessel density, skeletonized vessel density, fractal dimension, and intersections and average vessel diameter ...

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    24. Human Parafoveal Capillary Vascular Anatomy and Connectivity Revealed by Optical Coherence Tomography Angiography

      Human Parafoveal Capillary Vascular Anatomy and Connectivity Revealed by Optical Coherence Tomography Angiography

      Purpose : To assess the connection among arterioles, venules, and capillaries in three retinal capillary plexuses using optical coherence tomography angiography (OCTA). Methods : This was a prospective, cross-sectional, observational study including 20 eyes of 10 healthy subjects. En face and cross-sectional OCTA images were segmented to study the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP). Using thin slabs and manual segmentation within the three plexuses, we examined the connections between the large-caliber superficial vessels within a 3 × 3 mm 2 OCTA scan (arterioles and venules) and the smaller capillaries in each plexus. Results : Twenty eyes of 10 healthy subjects ...

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    1-24 of 58 1 2 3 »
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