1. Articles in category: Ophthalmology

    577-600 of 8719 « 1 2 ... 22 23 24 25 26 27 28 ... 362 363 364 »
    1. Learning layer-specific edges for segmenting retinal layers with large deformations

      Learning layer-specific edges for segmenting retinal layers with large deformations

      We present an algorithm for layer-specific edge detection in retinal optical coherence tomography images through a structured learning algorithm to reinforce traditional graph-based retinal layer segmentation. The proposed algorithm simultaneously identifies individual layers and their corresponding edges, resulting in the computation of layer-specific edges in 1 second. These edges augment classical dynamic programming based segmentation under layer deformation, shadow artifacts noise, and without heuristics or prior knowledge. We considered Duke’s online data set containing 110 B-scans of 10 diabetic macular edema subjects with 8 retinal layers annotated by two experts for experimentation, and achieved a mean distance error of ...

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    2. YOUR eyes and ears could help diagnose early signs of dementia and THIS is how

      YOUR eyes and ears could help diagnose early signs of dementia and THIS is how

      Scientists have also found an impaired sense of smell may predict dementia and could be an early indicator of the disease. A new study has found the thinning of the retinal nerve at the back of the eye can flag up impending neuro-degeneration. It was linked with poorer performance on cognitive tests including memory, numeric and verbal reasoning and reaction times. A protein called beta-amyloid builds up in the brains of people with Alzheimer's disease - forming into clumps and causing memory loss and confusion...The researchers carried out a type of eye scan called spectral domain optical coherence tomography ...

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    3. Apparatus and method for space-division multiplexing optical coherence tomography

      Apparatus and method for space-division multiplexing optical coherence tomography

      A space-division multiplexing optical coherence tomography apparatus and system is provided. In one embodiment, the system includes a light source, a reference arm, and a sample arm. The sample arm splits the sampling light into a plurality of sampling beams which may be scanned simultaneously onto a surface of a sample. An optical delay may be introduced into the sampling beams before scanning. A plurality of reflected light signals returned from the sample is collected. In one arrangement, the signals may be combined to produce a single reflected light signal. The reflected light signal(s) and a reference signal are ...

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    4. Radial Peripapillary Capillary Network Visualized Using Wide-Field Montage Optical Coherence Tomography Angiography

      Radial Peripapillary Capillary Network Visualized Using Wide-Field Montage Optical Coherence Tomography Angiography

      Purpose : We quantitatively analyzed the features of a radial peripapillary capillary (RPC) network visualized using wide-field montage optical coherence tomography (OCT) angiography in healthy human eyes. Methods : Twenty eyes of 20 healthy subjects were recruited. En face 3 × 3-mm OCT angiograms of multiple locations in the posterior pole were acquired using the RTVue XR Avanti, and wide-field montage images of the RPC were created. To evaluate the RPC density, the montage images were binarized and skeletonized. The correlation between the RPC density and the retinal nerve fiber layer (RNFL) thickness measured by an OCT circle scan was investigated. Results : The ...

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    5. Quantitative Optical Coherence Tomography Angiography of Radial Peripapillary Capillaries in Glaucoma, Glaucoma Suspect and Normal Eyes

      Quantitative Optical Coherence Tomography Angiography of Radial Peripapillary Capillaries in Glaucoma, Glaucoma Suspect and Normal Eyes

      Purpose To evaluate the quantitative characteristics of the radial peripapillary capillary (RPC) network in glaucoma, glaucoma suspect and normal eyes using speckle variance optical coherence tomography angiography (OCT-A). To determine correlations between RPC density, nerve fibre layer (NFL) thickness and visual field indices. Design Cross sectional study. Methods OCT-A images of RPCs were acquired at a single institution using a custom-built 1060nm system from three groups: unilateral glaucoma (10 eyes from 5 subjects); glaucoma suspects (6 eyes from 3 subjects); and normal control eyes (16 eyes from 9 normal subjects). Peripapillary NFL thickness measurements were determined using spectral-domain OCT. Glaucoma ...

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    6. CLINICAL SPECTRUM OF MACULAR-FOVEAL CAPILLARIES EVALUATED WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      CLINICAL SPECTRUM OF MACULAR-FOVEAL CAPILLARIES EVALUATED WITH OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To describe macular-foveal capillaries (MFC) by means of optical coherence tomography angiography and to identify the clinical spectrum of this angiographic feature. Methods: Patients with MFC presenting at the Medical Retina & Imaging Unit of the Department of Ophthalmology, University Vita-Salute San Raffaele in Milan were recruited. Patients underwent a complete ophthalmologic examination that included slit-lamp examination, fundus examination, measurement of best-corrected visual acuity, fundus autofluorescence, and spectral-domain optical coherence tomography (Spectralis HRA + OCT; Heidelberg Engineering, Heidelberg, Germany). Fluorescein angiography was performed in selected cases. Optical coherence tomography angiography was performed through Zeiss prototype (AngioPlex, CIRRUS HD-OCT models 5000; Carl ...

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    7. PERIPAPILLARY ARTERIAL RING OF ZINN-HALLER IN HIGHLY MYOPIC EYES AS DETECTED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      PERIPAPILLARY ARTERIAL RING OF ZINN-HALLER IN HIGHLY MYOPIC EYES AS DETECTED BY OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

      Purpose: To visualize the arterial circle of Zinn-Haller (ZHAC) in highly myopic patients by using OCT-A. Methods: Two hundred and fifty-three eyes of 146 consecutive patients with axial length >=26.5 mm who underwent OCT-A centered onto the optic disk were studied. Results: Arterial circle of Zinn-Haller was detectable on OCT-A images within the area of the parapapillary myopic conus in 26 (10%) of 253 eyes. The ZHAC was annular in 18 (69%) eyes, triangular in (15%) 4 eyes, and irregular (15%) in 4 eyes. The visibility of the ZHAC on OCT-A images was similar to the visibility on indocyanine ...

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    8. Evaluation of Early Graft Detachment After Descemet Membrane Endothelial Keratoplasty Using New Swept-Source Optical Coherence Tomography

      Evaluation of Early Graft Detachment After Descemet Membrane Endothelial Keratoplasty Using New Swept-Source Optical Coherence Tomography

      Purpose: To evaluate the ability of Swept-source optical coherence tomography (SS-OCT) in detecting early endothelial graft detachment after Descemet membrane endothelial keratoplasty (DMEK) and to determine the possible causes of graft detachment using 2 different protocols for anterior segment (AS) imaging. Methods: Eight eyes from 8 consecutive DMEK surgeries were evaluated. High-resolution images were captured with SS-OCT using 2 different radial protocols for AS imaging (16- and 6-mm radial protocols). Central and peripheral corneal changes were evaluated. Results: All eyes developed early graft detachment detectable with the SS-OCT. The 16-mm radial protocol scanned the cornea detecting early graft detachment in ...

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    9. OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ASSESSMENT OF VASCULAR EFFECTS OCCURRING AFTER AFLIBERCEPT INTRAVITREAL INJECTIONS IN TREATMENT-NAIVE PATIENTS WITH WET AMD

      OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY ASSESSMENT OF VASCULAR EFFECTS OCCURRING AFTER AFLIBERCEPT INTRAVITREAL INJECTIONS IN TREATMENT-NAIVE PATIENTS WITH WET AMD

      Purpose: To investigate vessel changes occurring after aflibercept injections in treatment-naive exudative age-related macular degeneration patients. Methods: Fifteen eyes of 15 patients affected by wet age-related macular degeneration were enrolled in the study. All the patients had a diagnosis of Type 1 choroidal neovascularization and were treated with 3 monthly aflibercept intravitreal injections (IVI). Subjects were evaluated by means of optical coherence tomography angiography at baseline, the day after the first injection and one month after both the first and the second IVI. At last, all the patients were followed up to 2 months after the third IVI. Results: Foveal ...

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    10. SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-BASED MICROSTRUCTURAL ANALYSIS OF RETINAL ARCHITECTURE POST INTERNAL LIMITING MEMBRANE PEELING FOR SURGERY OF IDIOPATHIC MACULAR HOLE REPAIR

      SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY-BASED MICROSTRUCTURAL ANALYSIS OF RETINAL ARCHITECTURE POST INTERNAL LIMITING MEMBRANE PEELING FOR SURGERY OF IDIOPATHIC MACULAR HOLE REPAIR

      Purpose: Spectral domain optical coherence tomography-based analysis of retinal architecture after internal limiting membrane peeling for macular hole surgery. Methods: Prospective, interventional study. Fifty eyes underwent the surgical procedure with minimum internal limiting membrane peel of 3 mm diameter. Automatic segmentation software was used to assess individual layers preoperatively and postoperatively, 1.5 millimeters medial and lateral to fovea at 3 months postoperative visit. Main outcome measures were final central macular thickness and variation in individual retinal layer thickness. Results: Mean central macular thickness postoperatively was 201 microns. Retinal thickening was observed, 1.5 mm medial to fovea (P < 0 ...

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    11. Evaluation of the conjuntival blebs using spectral domain optical coherence tomography after glaucoma surgery

      Evaluation of the conjuntival blebs using spectral domain optical coherence tomography after glaucoma surgery

      Objective to investigate whether optical coherence tomography (OCT) could demonstrate axonal loss through thinning of the retinal nerve fiber layer (RNFL) in multiple sclerosis (MS) patients. Furthermore, the degree of RNFL loss was compared in the different MS subgroups (with or without optic neuritis, affected or fellow eye, single episode or recurrent optic neuritis, relapsing remitting or progressive MS). RNFL thinning was also determined in MS patients who had serial OCT without any intervening clinical optic neuritis. Design: Retrospective chart review. Setting: Academic tertiary care MS centers. Participants: 177 patients (334 eyes) with multiple sclerosis, with or without optic neuritis ...

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    12. University of California at Berkely Receives NIH Grant for Interferometric Optophysiology of the Human Retina

      University of California at Berkely Receives NIH Grant for Interferometric Optophysiology of the Human Retina

      University of California at Berkeley Receives a 2016 NIH Grant for $662,015 for Interferometric Optophysiology of the Human Retina. The principal investigator is Austin Roorda. The program began in 2015 and ends in 2020. Below is a summary of the proposed work. Our goal is to develop a new technology for non-invasive optical monitoring of activity of individual retinal neurons and their light-driven inputs at cellular resolution, in the living human retina. If successful, this technology will provide an entirely new and objective approach to understand and monitor treatment of retinal disease, thereby transforming scientific studies of the eye ...

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    13. Delineation of capillary dropout in the deep retinal capillary plexus using optical coherence tomography angiography in a patient with Purtscher’s retinopathy exhibiting normal fluorescein angiography findings: a case report

      Delineation of capillary dropout in the deep retinal capillary plexus using optical coherence tomography angiography in a patient with Purtscher’s retinopathy exhibiting normal fluorescein angiography findings: a case report

      Background Fat embolism in the deep retinal capillary plexus is one of the reported mechanisms underlying central/paracentral scotoma in patients with Purtscher’s retinopathy. Here we report the clear delineation of capillary dropout in the deep capillary plexus using optical coherence tomography angiography (OCTA) in a chronic case of unexplained scotoma that developed after femoral fracture. The patient exhibited normal fluorescein angiography (FA) findings and a normal retinal appearance. Case presentation A 42-year-old Japanese man with a history of bilateral, unexplained paracentral scotoma that developed after femoral fracture and pulmonary fat embolism due to a car accident 20 years ...

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    14. Optical Coherence Tomography Angiography Findings in Coats' Disease

      Optical Coherence Tomography Angiography Findings in Coats' Disease

      BACKGROUND AND OBJECTIVE: To describe optical coherence tomography angiography (OCTA) findings in patients with unilateral Coats' disease. PATIENTS AND METHODS: Retrospective, observational case series of four patients with unilateral Coats' disease who underwent bilateral OCTA imaging. RESULTS: Bilateral macular OCTA findings of eight eyes are described. An abnormal foveal avascular zone (FAZ) with inner retinal vessels traversing the avascular zone in the superficial capillary plexus was visible on OCTA in the affected eye of all four patients. A similarly abnormal FAZ was noted on OCTA in the clinically normal fellow eye in two of the four patients (50%). CONCLUSION: OCTA ...

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    15. Optical Coherence Tomography Angiography in Fovea Plana

      Optical Coherence Tomography Angiography in Fovea Plana

      Fovea plana is characterized by the anatomical absence of the foveal pit in eyes with normal visual function. The authors have analyzed three cases of idiopathic fovea plana with optical coherence tomography angiography (OCTA). As previously reported, the authors found the absence of a foveal avascular zone in all cases with OCTA; however, a preserved fusion of both the superficial and the deep capillary plexuses was found around the foveal center. This novel observation cannot be detected with conventional dye-based angiography, in which the deep capillary plexus is not visualized.

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    16. Optical Coherence Tomography Evaluation of Valsalva-Induced Suprachoroidal Hemorrhage

      Optical Coherence Tomography Evaluation of Valsalva-Induced Suprachoroidal Hemorrhage

      Suprachoroidal hemorrhage is typically observed in patients with hypotony in the context of intraocular surgery and trauma. We report a rare presentation of suprachoroidal hemorrhage associated with emesis (Valsalva maneuver) in a myopic patient with few other identifiable risk factors. This diagnosis was confirmed with wide-field fundus photography and B-scan ultrasound and was localized to the suprachoroidal space using both enhanced depth and swept-source optical coherence tomography imaging. This case is unique in its presentation and demonstrates the utility of newer imaging techniques to localize hemorrhages using a multimodal approach.

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    17. Spectral-Domain Optical Coherence Tomography, Wide-Field Photography, and Fundus Autofluorescence Correlation of Posterior Ophthalmomyiasis Interna

      Spectral-Domain Optical Coherence Tomography, Wide-Field Photography, and Fundus Autofluorescence Correlation of Posterior Ophthalmomyiasis Interna

      Posterior ophthalmomyiasis interna is a rare, potentially devastating infestation of the posterior segment by fly larvae. The authors report the first demonstration of spectral-domain optical coherence tomography (SD-OCT) (Spectralis; Heidelberg Engineering, Heidelberg, Germany), wide-field angiography (Optos, Dunfermline, Scotland) and photography, and fundus autofluorescence with temporal progression during a period of 6 months. A 12-year-old white female presented with acute, painless vision loss with hand motions visual acuity. No larva was visible, so she was treated with oral ivermectin. Visual acuity improved to 20/80. OCT demonstrated hyporeflective spaces of the outer retina and retinal pigment epithelium, which resolved during 1-month ...

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    18. Quantification of choroidal neovascularization vessel length using optical coherence tomography angiography

      Quantification of choroidal neovascularization vessel length using optical coherence tomography angiography

      Quantification of choroidal neovascularization (CNV) as visualized by optical coherence tomography angiography (OCTA) may have importance clinically when diagnosing or tracking disease. Here, we present an automated algorithm to quantify the vessel skeleton of CNV as vessel length. Initial segmentation of the CNV on en face angiograms was achieved using saliency-based detection and thresholding. A level set method was then used to refine vessel edges. Finally, a skeleton algorithm was applied to identify vessel centerlines. The algorithm was tested on nine OCTA scans from participants with CNV and comparisons of the algorithm’s output to manual delineation showed good agreement

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    19. Optical Coherence Tomography in High Myopia

      Optical Coherence Tomography in High Myopia

      Optical coherence tomography (OCT) is a precise technology that can be used for interrogating tissue structure and function noninvasively, painlessly, and quickly using near-infrared light. At its inception, OCT was typically a tool for assessing tissue thickness. Time-domain OCT is fast enough to scan a circle centered on the optic nerve head (circumpapillary) to assess retinal nerve fiber layer (RNFL) thickness. With the development of spectral-domain OCT, volumetric (3-dimensional) scanning becomes feasible.

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    20. Repeatability of automated vessel density measurements using optical coherence tomography angiography

      Repeatability of automated vessel density measurements using optical coherence tomography angiography

      Aims To determine the repeatability of optical coherence tomography angiography (OCT-A)-derived automated vessel density measurements in the superficial retinal layer (SRL) and deep retinal layer (DRL) in healthy individuals. Methods 41 eyes of 21 healthy individuals were included in this study. OCT-A was performed using the NIDEK RS-3000 Advance with prototype OCT-A software. Each subject underwent two scanning sessions with 5–10 min in between. En face images of the retinal vasculature were generated using the default segmentation for SRL and DRL. Automated vessel density measurements were compared between the two sessions. The intraclass correlation coefficients (ICCs) and coefficient ...

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    21. Optical coherence tomography (OCT) angiography findings in retinal arterial macroaneurysms

      Optical coherence tomography (OCT) angiography findings in retinal arterial macroaneurysms

      Background Optical coherence tomography angiography is a novel imaging technique that allows dyeless in vivo visualization of the retinal and choroidal vasculature. The purpose of this study was to describe optical coherence tomography (OCT) angiography findings in patients with retinal arterial macroaneurysms (RAMs). Methods Three eyes of three patients with RAMs were retrospectively included. Fundus photography, OCT, fluorescein angiography (FA), and OCT angiography were performed. The entire imaging data was analyzed in detail. Results OCT angiography could detect the RAMs noninvasively without dye injection. By simultaneously observing the OCT scans, it was possible to determine the depth of the RAMs ...

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    22. Evaluation of posterior vitreous detachment after uneventful phacoemulsification surgery by optical coherence tomography and ultrasonography

      Evaluation of posterior vitreous detachment after uneventful phacoemulsification surgery by optical coherence tomography and ultrasonography

      Background The aim was to investigate the effect of uneventful phacoemulsification on vitreoretinal interface evaluated by optical coherence tomography (OCT) and ultrasound. Methods One hundred and fifty eyes were evaluated for the presence or absence of posterior vitreous detachment by ultrasound and OCT prior to cataract surgery. Only those eyes with intact vitreoretinal adhesion were included in the study. All patients underwent cataract surgery. At one month, three months and six months, all patients were assessed with OCT and ultrasound. The data were analysed for statistical significance. Results The study was carried out on 30 of 31 patients with no ...

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    23. Image artefacts in swept-source optical coherence tomography angiography

      Image artefacts in swept-source optical coherence tomography angiography

      Purpose To describe optical coherence tomography angiography (OCTA) image artefacts in eyes with and without ocular pathologies. Methods The OCTA images of healthy subjects and patients with age-related macular degeneration, diabetic retinopathy and retinal vascular occlusions were retrospectively reviewed. All OCTA images were obtained using a swept-source OCTA instrument (Triton, Topcon). The frequency of various image artefacts including segmentation, banding, motion, projection, masking, unmasking, doubling of the retinal vessels, blink, stretching, out-of-window and crisscross artefacts was assessed. The impact of the artefact on the grading of the images for the foveal avascular zone in deep and superficial retinal layers, capillary ...

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