1. Articles from amani a. fawzi

    1-24 of 47 1 2 »
    1. 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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    2. 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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    3. 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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    4. 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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    5. 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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    6. 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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    7. 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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    8. 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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    9. 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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    10. 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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    11. 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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    12. 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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    13. 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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    14. Visible-light optical coherence tomography oximetry based on circumpapillary scan and graph-search segmentation

      Visible-light optical coherence tomography oximetry based on circumpapillary scan and graph-search segmentation

      Visible-light optical coherence tomography (vis-OCT) enables retinal oximetry by measuring the oxygen saturation of hemoglobin (sO 2 ) from within individual retinal blood vessels. The sO 2 calculation requires reliable estimation of the true spectrum of backscattered light from the posterior vessel wall. Unfortunately, subject motion and image noise make averaging from multiple A-lines at the same depth position challenging, and lead to inaccurate sO 2 estimation. In this study, we developed an algorithm to reliably extract the backscattered light’s spectrum. We used circumpapillary scanning to sample the vessels repeatedly at the same location. A combination of cross-correlation and graph-search ...

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    15. Morphological Implications of Vascular Structures Not Visualized on Optical Coherence Tomography Angiography in Retinal Vein Occlusion

      Morphological Implications of Vascular Structures Not Visualized on Optical Coherence Tomography Angiography in Retinal Vein Occlusion

      BACKGROUND AND OBJECTIVE: Advanced retinal imaging can improve understanding of retinal vein occlusion (RVO) pathology. The authors aimed to characterize the vascular pathology of RVO on en face optical coherence tomography (OCT) and OCT angiography (OCTA). PATIENT AND METHODS: This was a cross-sectional study including 17 eyes with RVO. The authors identified discordance between vasculature on en face OCT and flow on OCTA, which was correlated with structural findings at the corresponding location on OCT B-scans. RESULTS: Six eyes had vessels that were seen on OCT without flow on OCTA. The most clinically relevant finding was preserved inner retinal layers ...

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    16. RESIDUAL CHOROIDAL VESSELS IN ATROPHY CAN MASQUERADE AS CHOROIDAL NEOVASCULARIZATION ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Introducing a Clinical and Software Approach

      RESIDUAL CHOROIDAL VESSELS IN ATROPHY CAN MASQUERADE AS CHOROIDAL NEOVASCULARIZATION ON OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY: Introducing a Clinical and Software Approach

      Purpose: To present a postprocessing approach in optical coherence tomography angiography (OCTA) to facilitate the visualization and interpretation of lesions in age-related macular degeneration with coexisting atrophy and choroidal neovascularization (CNV). Methods: This retrospective study included 32 eyes of 26 patients with atrophy and treated CNV and 8 eyes with treatment-naive geographic atrophy . En face optical coherence tomography slabs highlighting atrophy were pseudocolored and merged with the corresponding OCTA. Cross-sectional optical coherence tomography and postprocessed OCTA were analyzed to identify CNV and normal choroidal vessels in relationship to the atrophy. We correlate the OCTA findings with those in a donor ...

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    17. Importance of Considering the Middle Capillary Plexus on OCT Angiography in Diabetic Retinopathy

      Importance of Considering the Middle Capillary Plexus on OCT Angiography in Diabetic Retinopathy

      Purpose : To quantify microvasculature changes in the superficial (SCP), middle (MCP), and deep capillary plexuses (DCP) in diabetic retinopathy (DR). Methods : Retrospective cross-sectional study at a tertiary academic referral center, in which 26 controls (44 eyes), 27 diabetic subjects without retinopathy (44 eyes), 32 subjects with nonproliferative retinopathy (52 eyes), and 27 subjects with proliferative retinopathy (40 eyes) were imaged with optical coherence tomography angiography (OCTA). Outcome measures included parafoveal vessel density (VD), percentage area of nonperfusion (PAN), and adjusted flow index (AFI) at the different plexuses. Results : MCP VD and MCP AFI decreased with worsening DR, while PAN increased ...

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    18. MULTILEVEL ISCHEMIA IN DISORGANIZATION OF THE RETINAL INNER LAYERS ON PROJECTION-RESOLVED OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      MULTILEVEL ISCHEMIA IN DISORGANIZATION OF THE RETINAL INNER LAYERS ON PROJECTION-RESOLVED OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To examine the relationship between ischemia and disorganization of the retinal inner layers ( DRIL ). Methods: Cross-sectional retrospective study of 20 patients (22 eyes) with diabetic retinopathy presenting to a tertiary academic referral center, who had DRIL on structural optical coherence tomography ( OCT ) using Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany) and OCT angiography with XR Avanti (Optovue Inc, Fremont, CA) on the same day. Optical coherence tomography angiography images were further processed to remove flow signal projection artifacts using a software algorithm adapted from recent studies. Retinal capillary perfusion in the superficial capillary plexuses, middle capillary plexuses, and deep ...

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    19. OCT Angiography Imaging in Serpiginous Choroidopathy

      OCT Angiography Imaging in Serpiginous Choroidopathy

      Purpose To report OCTA findings in 3 cases, 2 active and 1 inactive, of serpiginous choroidopathy (SC) and describe OCTA changes in response to treatment. Design Retrospective case series. Participants We studied 6 eyes of 3 patients with SC. Methods Retrospective case series of 3 patients with SC undergoing multimodal imaging, including OCTA. In 1 treated eye, both pre- and posttreatment images were compared. Main Outcome Measures Description of OCTA findings in patients with SC. Results In the active phase, OCTA images show an apparent absence of the choriocapillaris with variable outer retinal and retinal pigment epithelial thickening. After treatment ...

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    20. Assessment Of Retinal Blood Flow In Diabetic Retinopathy Using Doppler FOURIER-DOMAIN Optical Coherence Tomography

      Assessment Of Retinal Blood Flow In Diabetic Retinopathy Using Doppler FOURIER-DOMAIN Optical Coherence Tomography

      Purpose: To evaluate retinal blood flow measurements in normal eyes and eyes with varying levels of diabetic retinopathy (DR) using Doppler Fourier-domain optical coherence tomography (FD-OCT). Methods: Twenty-two eyes of 19 subjects, 10 with severe nonproliferative DR (NPDR) and 12 with proliferative DR (PDR), were compared with 44 eyes of 40 healthy control subjects. All eyes were scanned by RTvue FD-OCT. Color disk photographs and cube/volume scans of the optic nerve head were obtained. Doppler OCT scans and accessory imaging data were imported into Doppler OCT of Retinal Circulation grading software to calculate TRBF and vascular parameters (e.g ...

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    21. Optical coherence tomography angiography of retinal vascular occlusions produced by imaging-guided laser photocoagulation

      Optical coherence tomography angiography of retinal vascular occlusions produced by imaging-guided laser photocoagulation

      Retinal vascular occlusive diseases represent a major form of vision loss worldwide. Rodent models of these diseases have traditionally relied upon a slit-lamp biomicroscope to help visualize the fundus and subsequently aid delivery of high-power laser shots to a target vessel. Here we describe a multimodal imaging system that can produce, image, and monitor retinal vascular occlusions in rodents. The system combines a spectral-domain optical coherence tomography system for cross-sectional structural imaging and three-dimensional angiography, and a fluorescence scanning laser ophthalmoscope for Rose Bengal monitoring and high-power laser delivery to a target vessel. This multimodal system facilitates the precise production ...

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    22. MULTIMODAL IMAGING OF ACUTE EXUDATIVE POLYMORPHOUS VITELLIFORM MACULOPATHY WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AND ADAPTIVE OPTICS SCANNING LASER OPHTHALMOSCOPY

      MULTIMODAL IMAGING OF ACUTE EXUDATIVE POLYMORPHOUS VITELLIFORM MACULOPATHY WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY AND ADAPTIVE OPTICS SCANNING LASER OPHTHALMOSCOPY

      Purpose: To report a case of acute exudative polymorphous vitelliform maculopathy including the findings of optical coherence tomography angiography and adaptive optics scanning laser ophthalmoscopy. Methods: Findings on clinical examination, color fundus photography, spectral-domain optical coherence tomography, infrared reflectance, autofluorescence, optical coherence tomography angiography, and adaptive optics scanning laser ophthalmoscopy. Results: A 54-year-old white man with no significant medical history and history of smoking presented with bilateral multiple serous and vitelliform detachments consistent with acute exudative polymorphous vitelliform maculopathy. Extensive infectious, inflammatory, and malignancy workup was negative. Spectral-domain optical coherence tomography showed thickened, hyperreflective ellipsoid zone, subretinal fluid, and focal ...

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    23. Anterior Segment Optical Coherence Tomography Angiography for Identification of Iris Vasculature and Staging of Iris Neovascularization

      Anterior Segment Optical Coherence Tomography Angiography for Identification of Iris Vasculature and Staging of Iris Neovascularization

      Purpose/Aim of the study : To assess the ability of optical coherence tomographic angiography (OCTA) to visualize the normal iris vasculature as well as neovascularization of the iris (NVI). Materials and Methods : Study participants with healthy eyes, patients at risk of NVI development and patients with active or regressed NVI were consecutively included in this cross-sectional observational study. Imaging was performed using a commercially available OCTA system (RTVue- XR Avanti, Optovue Inc., Fremont, CA, USA). Abnormal iris vessels were graded on OCTA according to a modified clinical staging system and compared to slitlamp and gonioscopic findings. Results : Fifty eyes of ...

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    24. Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

      Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

      We measured hemoglobin oxygen saturation (sO 2 ) in the retinal circulation in healthy humans using visible-light optical coherence tomography (vis-OCT). The measurements showed clear oxygenation differences between central retinal arteries and veins close to the optic nerve head. Spatial variations at different vascular branching levels were also revealed. In addition, we presented theoretical and experimental results to establish that noises in OCT intensity followed Rice distribution. We used this knowledge to retrieve unbiased estimation of true OCT intensity to improve the accuracy of vis-OCT oximetry, which had inherently lower signal-to-nose ratio from human eyes due to safety and comfort limitations ...

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