1. Articles in category: Ophthalmology

    25-48 of 14095 « 1 2 3 4 5 ... 586 587 588 »
    1. Optical coherence tomography indices in the diagnosis and discrimination of stages of primary open-angle glaucoma in an African population

      Optical coherence tomography indices in the diagnosis and discrimination of stages of primary open-angle glaucoma in an African population

      Purpose The objective of this study was to determine the structure–function association of the optical coherence tomography (OCT) indices (retinal nerve fibre layer (RNFL), ganglion cell complex (GCC) and optic nerve head (ONH) parameters) with the visual field sensitivity and their diagnostic ability at different stages of primary open-angle glaucoma (POAG) among a population West-African descent. Methods The study was a clinic-based prospective study which employed purposive sampling in the recruitment of clinically diagnosed POAG and non-glaucoma patients. OCT and visual field test (VFT) results were collated. Classification of the POAG cases was done using the Hodapp–Parrish–Anderson ...

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    2. Diagnostics in Ocular Imaging

      Diagnostics in Ocular Imaging

      This book presents a new avenue in the field of ophthalmology and sheds light on the field of eye imaging. With the increasing availability of electronic devices and their important role in both personal and professional aspects of human life, there is a growing need for perfect vision. Ophthalmic imaging is a major tool for screening and documenting eye diseases in both medical and surgical fields of ophthalmology and is also of use for ophthalmologists around the globe. The number of eye-imaging devices has increased dramatically, however undiagnosed or poorly managed eye diseases remain a significant cause of ocular and ...

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    3. Analysis of Retinochoroidal Vasculature in Underweight Women Using Optical Coherence Tomography Angiography

      Analysis of Retinochoroidal Vasculature in Underweight Women Using Optical Coherence Tomography Angiography

      Cachectic patients and controls undergoing a comprehensive ophthalmologic examination. The imaging of all subjects is undertaken using a commercial OCTA device with a scan rate of 70,000 A-scans/s, scan beam wavelength of 840 ± 10 nm and bandwidth of 45 nm. All measurements are performed between 10:00 and 12:00 on the same day. The OCTA images are independently graded and assessed by two retinal specialists. The software automatically segmented these full-thickness retinal scans into the superficial and deep inner retinal vascular plexuses, outer retina, and choriocapillaris (CC). The vascular density in the superficial and deep retinal vascular ...

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    4. Association Between Retinal Microvasculature and Optic Disc Alterations in Non-pathological High Myopia With OCTA

      Association Between Retinal Microvasculature and Optic Disc Alterations in Non-pathological High Myopia With OCTA

      Non-pathological high myopia patients and controls undergoing a comprehensive ophthalmologic examination are included. The Optical Coherence Tomography Angiography (OCTA) software automatically segments these full-thickness retinal scans into the superficial and deep inner retinal vascular plexuses, outer retina, and choriocapillaris (CC). The vascular density in the superficial and deep retinal vascular zones is calculated automatically by the software, and the foveal avascular zone (FAZ) and foveal density (FD) are also automatically determined. Choroidal thickness is calculated manually by two retinal specialists, and the average value was used.

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    5. Generation of dewarped OCT B-scan images

      Generation of dewarped OCT B-scan images

      A method of generating a look-up table, LUT, for constructing a dewarped B-scan image from A-scans of a cropped part of a sequence of acquired OCT A-scans, the LUT associating each of a plurality of pixel arrays that are to form the dewarped B-scan image with a respective A-scan in the cropped part. The method comprises: using an indication of a spatial distribution of scan locations of A-scans to determine a dewarp function for selecting, from among acquired A-scans, A-scans having uniformly spaced scan locations; using the function and cropping information, in accordance with which the cropped part is cropped ...

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      Mentions: Optos
    6. Systems and methods for generating and displaying OCT angiography data using variable interscan time analysis

      Systems and methods for generating and displaying OCT angiography data using variable interscan time analysis

      An imaging (e.g., with an optical coherence tomography system) method that includes 1) acquiring repeated B-scans in a manner consistent with forming images, 2) processing the acquired images according to a variable interscan time analysis (VISTA) method, and 3) generating and displaying a color-mapped image pixel color of the color-mapped image fluid flow speed, or a related quantity.

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    7. Central Macular Thickness in a Healthy Mexican Population Using Huvitz Optical Coherence Tomography

      Central Macular Thickness in a Healthy Mexican Population Using Huvitz Optical Coherence Tomography

      Objective: To determine normal macular thickness values in a healthy Mexican population and its variation by age and gender using Huvitz spectral-domain optical coherence tomography (HOCT-1F). Methods: This cross-sectional study included 211 consecutive eyes from clinically normal subjects (66 men, 145 women) between October 2018 and December 2018, with best-corrected visual acuities better than 20/30. One eye was selected for the macular scan using the Huvitz OCT (Huvitz OCT-1F, HOCT-1F, Huvitz Co., Ltd., Republic of Korea) with an automated segmentation algorithm. Three vertical and horizontal scans, centered on the fovea with an area of 9 mm, and a color ...

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    8. Longitudinal Swept Source Optical Coherence Tomography Angiography Of Extrafoveal Polyps After Combination Therapy

      Longitudinal Swept Source Optical Coherence Tomography Angiography Of Extrafoveal Polyps After Combination Therapy

      Purpose: To study the efficacy of swept source optical coherence tomography angiography (SSOCTA) to longitudinally follow up patients with extrafoveal polyps post laser photocoagulation and anti VEGF injection. Methods: Observational case series. Four patients diagnosed as polypoidal choroidal vasculopathy (PCV) with extrafoveal polyps on multimodal imaging were followed up serially on SSOCT, en face and cross-sectional SSOCTA at a month and then 3 monthly for a year. Indocyanine green angiography (ICGA) was repeated at 4 months and one year. Patients: 4 patient case series. Results: Anatomical regression of extrafoveal polyps was documented on a combination of en face and cross-sectional ...

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    9. Disruption of the outer segments of the photoreceptors on OCT as a feature of vitamin A deficiency

      Disruption of the outer segments of the photoreceptors on OCT as a feature of vitamin A deficiency

      Purpose: To describe the optical coherence tomography features of vitamin A deficiency. Methods: Case series includes three male patients aged 50-66 years with vitamin A deficiency and visual symptoms ranging from 2-8 months. Examination included optical coherence tomography (OCT), fundus autofluorescence imaging (FAF), full-field electroretinography (ERG) and laboratory work-up. Results: Patient 1 had inoperable pancreatic neuroendocrine tumour and presented with worsening nyctalopia. The ERG showed absent rod function two months after the onset of symptoms, followed by a decrease of cone function eight months after the onset. OCT showed poorly distinguishable outer segments of the photoreceptors (OS) with the disappearance ...

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    10. Retinal layer thicknesses retrieved with different segmentation algorithms from optical coherence tomography scans acquired under different signal-to-noise ratio conditions

      Retinal layer thicknesses retrieved with different segmentation algorithms from optical coherence tomography scans acquired under different signal-to-noise ratio conditions

      Glaucomatous damage can be quantified by measuring the thickness of different retinal layers. However, poor image quality may hamper the accuracy of the layer thickness measurement. We determined the effect of poor image quality (low signal-to-noise ratio) on the different layer thicknesses and compared different segmentation algorithms regarding their robustness against this degrading effect. For this purpose, we performed OCT measurements in the macular area of healthy subjects and degraded the image quality by employing neutral density filters. We also analysed OCT scans from glaucoma patients with different disease severity. The algorithms used were: The Canon HS-100’s built-in algorithm ...

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    11. The Effect of Anti-Vascular Endothelial Growth Factor on Retinal Microvascular Changes in Diabetic Macular Edema Using Swept-Source Optical Coherence Tomography Angiography

      The Effect of Anti-Vascular Endothelial Growth Factor on Retinal Microvascular Changes in Diabetic Macular Edema Using Swept-Source Optical Coherence Tomography Angiography

      Purpose: This study evaluates the effect of anti-vascular endothelial growth factor (anti-VEGF) therapy on microaneurysm changes and foveal avascular zone (FAZ) using optical coherence tomography angiography (OCTA) in patients with diabetic macular edema (DME). Design: Prospective observational study. Materials and Methods: This study involved patients with DME undergoing anti-VEGF treatment (aflibercept, ranibizumab, and bevacizumab). Macula OCTA images were obtained before (visit 0) and 1 month after (visit 1) anti-VEGF injection. Microaneurysm counts were performed, and the FAZ was evaluated in the superficial capillary plexus (SCP) and deep capillary plexus (DCP). The differences in microaneurysms, FAZ, and clinical correlations were analyzed ...

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    12. Optical Coherence Tomography Angiography Assessment of Macular Choriocapillaris and Choroid Following Panretinal Photocoagulation in a Diverse Population With Advanced Diabetic Retinopathy

      Optical Coherence Tomography Angiography Assessment of Macular Choriocapillaris and Choroid Following Panretinal Photocoagulation in a Diverse Population With Advanced Diabetic Retinopathy

      Purpose: The aim of this study was to evaluate choroidal and retinal microvasculature with optical coherence tomography angiography (OCTA) after panretinal photocoagulation (PRP) for diabetic retinopathy in a primarily Hispanic and Asian population . Design: Retrospective study. Methods: Eyes were examined by OCTA in the macula (3 × 3 mm) just before PRP treatment and 1 to 3 months afterwards. Choroidal thickness (CT) and central retinal thickness (CRT) were measured. Choroidal flow signal voids (CFSV) and choriocapillaris flow signal voids (CCFSV) were acquired. Retinal microvasculature parameters, including superficial and deep vessel density, superficial and deeper perfusion density, foveal avascular zone area, perimeter ...

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    13. Suspended Scattering Particles in Motion May Influence Optical Coherence Tomography Angiography Vessel Density Metrics in Eyes with Diabetic Macular Edema

      Suspended Scattering Particles in Motion May Influence Optical Coherence Tomography Angiography Vessel Density Metrics in Eyes with Diabetic Macular Edema

      Purpose: To study the effect of the suspended scattering particles in motion (SSPiM) on optical coherence tomography angiography (OCTA) vessel density metrics in eyes with diabetic macular edema (DME) Methods: Thirty-four eyes with DME from 27 patients (16 males and 11 females, 61.4 ± 9.6 years) with DME were included in this retrospective cohort study. Among these eyes, 19 (55.9%) showed the SSPiM artifact on OCTA. All participants received 3-mm and 6-mm optical coherence tomography angiography (OCTA) imaging. Perfusion density and skeletonized vessel density were calculated for the superficial capillary plexus (SCP) and the deep capillary plexus (DCP ...

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    14. Multiclass retinal disease classification and lesion segmentation in OCT B-scan images using cascaded convolutional networks

      Multiclass retinal disease classification and lesion segmentation in OCT B-scan images using cascaded convolutional networks

      Disease classification and lesion segmentation of retinal optical coherence tomography images play important roles in ophthalmic computer-aided diagnosis. However, existing methods achieve the two tasks separately, which is insufficient for clinical application and ignores the internal relation of disease and lesion features. In this paper, a framework of cascaded convolutional networks is proposed to jointly classify retinal diseases and segment lesions. First, we adopt an auxiliary binary classification network to identify normal and abnormal images. Then a novel, to the best of our knowledge, U-shaped multi-task network, BDA-Net, combined with a bidirectional decoder and self-attention mechanism, is used to further ...

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    15. Pathological-Corneas Layer Segmentation and Thickness Measurement in OCT Images

      Pathological-Corneas Layer Segmentation and Thickness Measurement in OCT Images

      Purpose : The purpose of this study was to propose a new algorithm for the segmentation and thickness measurement of pathological corneas with irregular layers using a two-stage graph search and ray tracing. Methods : In the first stage, a graph, with only gradient edge-cost, is used to segment the air-epithelium and endothelium-aqueous boundaries. In the second stage, a graph, with gradient, directional, and multiplier edge-cost, is used to correct segmentation. The optical coherence tomography (OCT) image is flattened using the air-epithelium boundary and a graph search is used to segment the epithelium-Bowman's and Bowman's-stroma boundaries. Then, the OCT image ...

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    16. Suprachoroidal hemorrhage due to Valsalva maneuver, importance of enhanced depth imaging optical coherence tomography in differential diagnosis

      Suprachoroidal hemorrhage due to Valsalva maneuver, importance of enhanced depth imaging optical coherence tomography in differential diagnosis

      We describe a case report of a spontaneous suprachoroidal hemorrhage, in which the enhanced depth imaging optical coherence tomography (OCT-EDI) is extremely useful in establish the differential diagnosis with a choroidal tumor. A 70 year-old woman was referred with a central scotoma after a Valsalva maneuver. In the posterior pole we observed a grey bilobed subretinal mass with the appearance of a choroidal tumor. OCT-EDI revealed an optically dark region with a scalloped anterior tumor contour and subretinal fluid, the choroicapillaris appeared to be intact and displaced anteriorly. The diagnosis was a suprachoroidal hemorrhage and it resolved in 12 weeks ...

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    17. Keratoconus Detection using OCT Corneal and Epithelial Thickness Map Parameters and Patterns

      Keratoconus Detection using OCT Corneal and Epithelial Thickness Map Parameters and Patterns

      Purpose: To detect keratoconus using optical coherence tomography (OCT) corneal map parameters and patterns. Setting: Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, USA DESIGN:: Cross-sectional observational study. Methods: A spectral-domain OCT was used to acquire corneal and epithelial thickness maps in normal, manifest keratoconic, subclinical keratoconic, and forme fruste keratoconic (FFK) eyes. A two-step decision tree was designed. An eye will be classified as keratoconus if both decision tree conditions are met: First, at least one of the four quantitative corneal thickness (minimum, minimum-maximum, superonasal-inferotemporal) and epithelial thickness (standard deviation) map parameters exceed cutoff values. Second, presence of ...

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    18. Optical Coherence Tomography in Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

      Optical Coherence Tomography in Mild Cognitive Impairment: A Systematic Review and Meta-Analysis

      Purpose: The use of optical coherence tomography (OCT) of the retina to detect inner retinal degeneration is being investigated as a potential biomarker for mild cognitive impairment (MCI) and Alzheimer's disease (AD), and an overwhelming body of evidence indicates that discovery of disease-modifying treatments for AD should be aimed at the pre-dementia clinical stage of AD, i.e., MCI. We aimed to perform a systematic review and meta-analysis on retinal OCT in MCI. Methods: We performed a systematic review of the English literature in three databases (PubMed, Embase, and Latindex) for studies that measured retinal thickness using OCT in ...

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    19. Melanin concentration and depolarization metrics measurement by polarization-sensitive optical coherence tomography

      Melanin concentration and depolarization metrics measurement by polarization-sensitive optical coherence tomography

      Imaging of melanin in the eye is important as the melanin is structurally associated with some ocular diseases, such as age-related macular degeneration. Although optical coherence tomography (OCT) cannot distinguish tissues containing the melanin from other tissues intrinsically, polarization-sensitive OCT (PS-OCT) can detect the melanin through spatial depolarization of the backscattered light from the melanin granules. Entropy is one of the depolarization metrics that can be used to detect malanin granules in PS-OCT and valuable quantitative information on ocular tissue abnormalities can be retrived by correlating entropy with the melanin concentration. In this study, we investigate a relationship between the ...

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    20. Novel deep learning method enables clinic-ready automated screening for diabetes-related eye disease

      Novel deep learning method enables clinic-ready automated screening for diabetes-related eye disease

      Researchers at Helmholtz Zentrum München together with LMU University Eye Hospital Munich and the Technical University of Munich (TUM) created a novel deep learning method that makes automated screenings for eye diseases such as diabetic retinopathy more efficient. Reducing the amount of expensive annotated image data that is required for the training of the algorithm, the method is attractive for clinics. In the use case of diabetic retinopathy, the researchers developed a screening algorithm that needs 75 percent less annotated data and achieves the same diagnostic performance of human experts

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    21. A recommended "minimum data set" framework for SD-OCT retinal image acquisition and analysis from the Atlas of Retinal Imaging in Alzheimer's Study (ARIAS)

      A recommended "minimum data set" framework for SD-OCT retinal image acquisition and analysis from the Atlas of Retinal Imaging in Alzheimer's Study (ARIAS)

      Introduction: We propose a minimum data set framework for the acquisition and analysis of retinal images for the development of retinal Alzheimer's disease (AD) biomarkers. Our goal is to describe methodology that will increase concordance across laboratories, so that the broader research community is able to cross-validate findings in parallel, accumulate large databases with normative data across the cognitive aging spectrum, and progress the application of this technology from the discovery stage to the validation stage in the search for sensitive and specific retinal biomarkers in AD. Methods: The proposed minimum data set framework is based on the Atlas ...

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    22. The role of OCT angiography in a rare case of malignant trasformation of the optic disc melanocytoma

      The role of OCT angiography in a rare case of malignant trasformation of the optic disc melanocytoma

      Abstract The melanocytoma is a benign, highly pigmented tumor, localized on or adjacent to the optic disc. Its malignant trasformation represents a rare event. We describe a case of a 43-years old woman returned to our observation 29 years later with a malignant melanoma from an optic disc melanocytoma evaluated by Optical Coherence Tomography Angiography (OCTA). OCTA is a valid, non-invasive, dyeless and reliable method that could improve the diagnosis of this rare case of malignant trasformation of an optic disc melanocytoma.

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    23. OCT angiography measured changes in the foveal avascular zone area after glaucoma surgery

      OCT angiography measured changes in the foveal avascular zone area after glaucoma surgery

      Background/aims: To evaluate quantitative changes in the foveal avascular zone (FAZ) area after glaucoma surgery using swept-source optical coherence tomography angiography (SS-OCTA). Methods: Fifty-four consecutive patients with primary open-angle glaucoma (POAG) who met the inclusion criteria and underwent unilateral glaucoma surgery to reduce intraocular pressure (IOP) between April 2018 and July 2019.Eyes underwent IOP-lowering glaucoma surgery and their fellow (non-surgical) eyes were included. OCTA of the macula was performed in both eyes before glaucoma surgery and 3 months postoperatively. Two blinded examiners reviewed the image quality. Within- and between-group comparisons of the FAZ area and correlation of the ...

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    24. Management of Stromal Herpes Simplex Virus Keratitis With Epithelial Ulceration Using Optical Coherence Tomography-Generated Corneal Thickness Maps

      Management of Stromal Herpes Simplex Virus Keratitis With Epithelial Ulceration Using Optical Coherence Tomography-Generated Corneal Thickness Maps

      Purpose: To report 2 cases of herpes simplex virus (HSV) stromal keratitis with epithelial ulceration that were managed using optical coherence tomography-generated pachymetric and corneal epithelial thickness maps. Methods: Two patients with a history of HSV keratitis with nonhealing epithelial defects were referred to the Athens Vision Eye Institute. Anterior segment optical coherence tomography-generated pachymetric and corneal epithelial thickness maps showed subclinical stromal edema and irregular epithelium, thus indicating diagnoses of HSV stromal keratitis with epithelial ulceration. The patients were administered topical preservative-free dexamethasone and oral antiviral therapy. Steroid tapering was guided by pachymetric and corneal epithelial thickness maps at ...

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      Mentions: Yale University
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