1. Articles in category: Ophthalmology

    1-24 of 14380 1 2 3 4 ... 598 599 600 »
    1. Systems and methods for reflectance-based projection-resolved optical coherence tomography angiography

      Systems and methods for reflectance-based projection-resolved optical coherence tomography angiography

      Embodiments provide systems and methods associated with a reflectance-based projection-resolved (rbPR) optical coherence tomography angiography (OCTA) algorithm which uses optical coherence tomography (OCT) reflectance to enhance the flow signal and suppress the projection artifacts in 3-dimensional OCTA. rbPR improves the vascular connectivity and improved the discrimination of the deeper plexus angiograms in healthy eyes, compared to prior PR-OCTA method. Additionally, rbPR removes flow projection artifacts more completely from the outer retinal slab in the eyes with age-related macular degeneration, and preserves vascular integrity of the intermediate and deep capillary plexuses in the eyes with diabetic retinopathy. Additionally, the rbPR method ...

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    2. Method for determining the topography of the cornea of an eye

      Method for determining the topography of the cornea of an eye

      A method for determining the topography of the cornea of an eye on the basis of an optical, contactless data capture. In the method for determining the topography of the cornea of an eye, which is based on a deflectometric method, the deflectometric measurements are carried out with the aid of a keratometric method by virtue of additional OCT-based scans being made at the keratometric measurement points, wherein the two measurement systems are registered to one another and both the keratometric and the OCT-based measurement values are recorded and used for mutual calibration to determine and output the topographic data ...

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    3. A Novel 3D Segmentation Approach for Extracting Retinal Layers from Optical Coherence Tomography Images

      A Novel 3D Segmentation Approach for Extracting Retinal Layers from Optical Coherence Tomography Images

      Purpose Accurate segmentation of retinal layers of the eye in 3‐D Optical Coherence Tomography (OCT) data provides relevant information for clinical diagnosis. This manuscript describes a 3D segmentation approach that uses an adaptive patient‐specific retinal atlas, as well as an appearance model for 3D OCT data. Methods To reconstruct the atlas of 3D retinal scan, the central area of the macula (macula mid‐area) where the fovea could be clearly identified, was segmented initially. Markov Gibbs Random Field (MGRF) including intensity, spatial information, and shape of 12 retinal layers were used to segment the selected area of retinal ...

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    4. Asymmetric response to ranibizumab in mixed choroidal neovascularization in a neovascular age-related macular degeneration diagnosed on OCT angiography

      Asymmetric response to ranibizumab in mixed choroidal neovascularization in a neovascular age-related macular degeneration diagnosed on OCT angiography

      Background To present a case report of a patient with a mixed choroidal neovascular membrane (CNV) with an asymmetric response to ranibizumab diagnosed on optical coherence tomography angiography (OCTa). Case presentation A 61-year-old male was referred to our department in September 2017 due to decreased vision in his left eye. Best-corrected visual acuity (BCVA) was 43 Early Treatment Diabetic Retinopathy Study (ETDRS) letters in the left eye. Macular edema was present in the left eye, and a mixed CNV was identified on the OCTa. Therapy with intravitreal ranibizumab was commenced. After 5 ranibizumab injections, the BCVA was 42 ETDRS letters ...

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    5. OCT-angiography detects longitudinal microvascular changes in glaucoma: a systematic review

      OCT-angiography detects longitudinal microvascular changes in glaucoma: a systematic review

      Background/aims Optical coherence tomography angiography (OCTA) allows the study of vessel density (VD). We intended to perform a systematic review of studies focusing on longitudinal changes in peripapillary and macular VD measurements in glaucoma. Methods A search was performed across MEDLINE, Scopus, ISI Web of Science and Google Scholar, using the following query from inception until 20 September 2019: ((“optical coherence tomography angiography”[tiab]) OR (optical coherence tomography angiography[MeSH]) OR (“OCTA”[tiab]) OR (“OCT-A”[tiab]) OR (“angio-OCT”[tiab]) OR (“OCT- angiography”[tiab]) OR (“OCT-angio”[tiab]) OR (“OCT-angiographie”[tiab])) AND (glaucom*[tiab] OR glaucoma[MeSH]). Prospective studies that quantitatively ...

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    6. In Vivo Quantitative Analysis of Anterior Chamber White Blood Cell Mixture Composition Using Spectroscopic Optical Coherence Tomography

      In Vivo Quantitative Analysis of Anterior Chamber White Blood Cell Mixture Composition Using Spectroscopic Optical Coherence Tomography

      Anterior uveitis is the most common form of intraocular inflammation, and one of its main signs is the presence of white blood cells (WBCs) in the anterior chamber (AC). Clinically, the true composition of cells can currently only be obtained using AC paracentesis, an invasive procedure to obtain AC fluid requiring needle insertion into the AC. We previously developed a spectroscopic optical coherence tomography (SOCT) analysis method to differentiate between populations of RBCs and subtypes of WBCs, including granulocytes, lymphocytes and monocytes, both in vitro and in ACs of excised porcine eyes. We have shown that different types of WBCs ...

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    7. Optical coherence tomography image for automatic classification of diabetic macular edema

      Diabetic macular edema (DME) is the dominant reason of diabetic visual loss, so early detection and treatment of DME is of great significance for the treatment of diabetes. Based on transfer learning, an automatic classification method is proposed to distinguish DME images from normal images in optical coherence tomography (OCT) retinal fundus images. Features of the DME are automatically identified and extracted by the pre-trained convolutional neural network (CNN), which only involves fine-tuning the VGGNet-16 network without any user intervention. An accuracy of 97.9% and a sensitivity of 98.0% are acquired with the OCT images in the Duke ...

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    8. Retinal nonperfusion in optical coherence tomography angiography

      Retinal nonperfusion in optical coherence tomography angiography

      Background: Retinal nonperfusion (NP) is a biomarker for assessment of the severity of diabetic retinopathy and retinal vein occlusion. However, various conditions mimic the retinal NP flow void signals that are observed in optical coherence tomography angiography (OCTA). Methods: In this review, the possible mechanisms for these similar void flow signals in OCTA were summarized, and the discrepancies between the evaluations of retinal NP with fluorescein angiography and OCTA were also investigated and evaluated in terms of size and morphology. Results and conclusion: Vascular occlusion, resulting in retinal ischemia, leads to a flow void signal, indicating retinal NP in OCTA ...

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    9. Evaluation of choroidal thickness in children with type 1 diabetes: the role of optical coherence tomography in diabetic retinopathy screening

      Evaluation of choroidal thickness in children with type 1 diabetes: the role of optical coherence tomography in diabetic retinopathy screening

      The present study aimed to evaluate choroidal changes and alternations within the structure of the retina prior to visible morphologic signs of diabetic retinopathy (DR) in pediatric type 1 diabetes (T1D) cases. Two hundred and six eyes of 103 pediatric patients with T1D without DR and 88 eyes of 44 healthy controls were enrolled. They underwent a comprehensive ophthalmic examination and optical coherence tomography evaluation. Choroidal thickness (ChT) measurements were performed manually on macular and peripapillary regions. There was no significant difference between the two groups in terms of age, intraocular pressure, and axial length (p > 0.05). ChT measurements ...

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    10. Evaluation of ocular hypoperfusion in patients with acromegaly by using optical coherence tomography angiography

      Evaluation of ocular hypoperfusion in patients with acromegaly by using optical coherence tomography angiography

      Purpose: This study aimed to evaluate the retinal blood vessel parameters and the foveal avascular zone (FAZ) area using optical coherence tomography angiography (OCTA) in patients with acromegaly in comparison with healthy controls. Methods: A total of 45 patients with acromegaly and 45 healthy controls were included in this study. In all patients, the vessel density (VD) of the deep and superficial macular vascular networks and the foveal avascular zone (FAZ) were measured using OCTA. The correlation of insulin-like growth factor 1 (IGF-1) level and disease duration with deep macular VD and FAZ values was analyzed. All parameters were registered ...

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    11. Retinal neurodegeneration in diabetic peripheral neuropathy by optical coherence tomography: a systematic review and meta-analysis

      Retinal neurodegeneration in diabetic peripheral neuropathy by optical coherence tomography: a systematic review and meta-analysis

      Purpose: The optical coherence tomography (OCT) has been used to evaluate the changes of retinal degeneration in patients with diabetic peripheral neuropathy (DPN) in recent years, but the results of previous studies were controversial. Therefore, a systematic review and meta-analysis was performed to evaluate the degree of retinal neurodegeneration in DPN measured by OCT. Methods: A comprehensive search of PubMed, Embase, Web of Science, Scopus, China Biomedical Literature (CBM), China National Knowledge Infrastructure (CNKI), VIP, and Wanfang databases were performed to identify studies that evaluate retinal neurodegeneration in DPN by using OCT. The included studies were critically reviewed and meta-analyses ...

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    12. Macular fibrosis in Coats’ disease demonstrated by Optical Coherence Tomography Angiography – new data toward pathophysiology

      Macular fibrosis in Coats’ disease demonstrated by Optical Coherence Tomography Angiography – new data toward pathophysiology

      Purpose: To analyze if Segmented Swept-Source Optical Coherence Tomography Angiography (SS OCT-A) can provide additional information on morphology and pathophysiology of macular fibrosis in Coats' patients. Methods: A consecutive case series of three male patients (5, 7 and 15 years old), with Coats' disease-related macular fibrosis (stage 2b-2 patients, 3b-1 patient). SS OCT-A 3×3 mm macular scans of affected eyes were performed. Results: In all three cases the inner portion of macular fibrosis displayed a dense network of vessels, continuing into deeper layers. This structure was similar to that observed in retinal angiomatous proliferations (RAP). There was associated loss ...

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    13. A comparison of optic disc area measured by confocal scanning laser tomography versus Bruch’s membrane opening area measured using optical coherence tomography

      A comparison of optic disc area measured by confocal scanning laser tomography versus Bruch’s membrane opening area measured using optical coherence tomography

      Background: Precise optic disc size measurements based on anatomically exact disc margins are fundamental for a correct assessment of glaucoma suspects. Computerized imaging techniques, such as confocal-scanning-laser-tomography (CSLT), which applies operator defined boundaries and optical-coherence-tomography (OCT), which incorporates an alternative detectable landmark (Bruch's-membrane-opening (BMO)), have simplified the planimetry of the optic disc and BMO-area, respectively. This study's objectives are to compare both modalities for area and to define a threshold for macro-BMO using BMO-OCT. Methods: Retrospectively, patients that simultaneously received CSLT and BMO-OCT scans were included. Their images were correlated and agreement was determined using Bland-Altman-analysis. The diagnostic ...

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    14. Diagnosis of optic nerve head drusen using enhanced depth imaging optical coherence tomography

      Diagnosis of optic nerve head drusen using enhanced depth imaging optical coherence tomography

      Purpose: To evaluate the efficacy of Enhanced Depth Imaging Optical Coherence Tomography (EDI-OCT) in differentiating between optic nerve head drusen (ONHD) and optic disc oedema (ODE). Methods: This was a cross-sectional study of 140 patients: 83 patients with ONHD (49 hidden and 34 visible), 20 patients with pseudopapilloedema (without drusen), and 37 patients with ODE. EDI-OCT of the optic nerve was performed, selecting one high-resolution line from the HD 5-line raster protocol. Two observers blindly evaluated the presence of a hyporeflective core surrounded by a hyperreflective margin or border. The sensitivity, specificity, predictive values and posttest probability were evaluated as ...

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    15. A pilot study investigating anterior segment optical coherence tomography angiography as a non-invasive tool in evaluating corneal vascularisation

      A pilot study investigating anterior segment optical coherence tomography angiography as a non-invasive tool in evaluating corneal vascularisation

      The current assessment of corneal vascularisation (CV) relies on slit-lamp examination, which may be subjective. Dye-based angiographies, like indocyanine green angiography (ICGA), allows for good visualisation of anterior segment blood vessels. However, ICGA is invasive and can be associated with systemic adverse effects. Anterior segment optical coherence tomography angiography (AS-OCTA) is a non-invasive tool that has been shown to successfully delineate CV. However, there are no previous studies that have reported if AS-OCTA can determine CV stage and activity. We used an established CV model in rabbits to examine serial AS-OCTA scans of CV development and regression following treatment with ...

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    16. Foveal avascular zone segmentation in optical coherence tomography angiography images using a deep learning approach

      Foveal avascular zone segmentation in optical coherence tomography angiography images using a deep learning approach

      The purpose of this study was to introduce a new deep learning (DL) model for segmentation of the fovea avascular zone (FAZ) in en face optical coherence tomography angiography (OCTA) and compare the results with those of the device’s built-in software and manual measurements in healthy subjects and diabetic patients. In this retrospective study, FAZ borders were delineated in the inner retinal slab of 3 × 3 enface OCTA images of 131 eyes of 88 diabetic patients and 32 eyes of 18 healthy subjects. To train a deep convolutional neural network (CNN) model, 126 enface OCTA images (104 eyes with ...

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    17. Repeatability of automated measurements by a new anterior segment optical coherence tomographer and biometer and agreement with standard devices

      Repeatability of automated measurements by a new anterior segment optical coherence tomographer and biometer and agreement with standard devices

      We assess repeatability of automatic measurements of a new anterior segment optical coherence tomographer and biometer (ANTERION) and their agreement with those provided by an anterior segment-optical coherence tomography device combined with Placido-disk corneal topography (MS-39) and a validated optical biometer (IOLMaster 500). A consecutive series of patients underwent three measurements with ANTERION and one with MS-39. A subgroup of patients underwent biometry also with IOLMaster 500. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (COV), and intraclass correlation coefficient (ICC). Agreement was investigated with the 95% limits of agreement. Paired t-test and Wilcoxon matched-pairs test ...

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    18. Microperimetry and Optical Coherence Tomography Changes in Type-1 Diabetes Mellitus without Retinopathy

      Microperimetry and Optical Coherence Tomography Changes in Type-1 Diabetes Mellitus without Retinopathy

      Background: We aimed to measure and correlate inner retinal layer (IRL) thickness and macular sensitivity by optical coherence tomography (OCT) and by microperimetry, respectively, in type 1 diabetes mellitus patients (DM1) without diabetic retinopathy (DR). Methods: Fifty-one DM1 patients and 81 age-matched healthy subjects underwent measurement of the axial length (AL), retinal thickness in the macular ETDRS areas by swept source (SS)-OCT and macular sensitivity by microperimeter. Results: The total retinal and IRL thicknesses were thicker in the DM1 group (p < 0.05) in practically all ETDRS areas, and they had a generalized decrease in sensitivity (p < 0.05 ...

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    19. Spectral Domain – Optical Coherence Tomography findings in Triple-A Syndrome – A case series from Pakistan

      Spectral Domain – Optical Coherence Tomography findings in Triple-A Syndrome – A case series from Pakistan

      Triple A Syndrome is an autosomal recessive entity involving multiple systems usually characterized by adrenal insufficiency, alacrimia and achalasia. The disease features include variable degrees of neurological and neuro-ophthalmic manifestations. Protein ALADIN encoded by the AAAS gene is found to be defective in Triple A Syndrome. Here we discuss a case series of five patients diagnosed as Triple A Syndrome. Clinically there was variable degree of optic atrophy in all the cases, which was further confirmed with spectral domain Optical Coherence Tomography The aim of this study was to publish the OCT based ONFL graphs of these unique cases, so ...

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    20. Feasibility of microscope-integrated swept-source optical coherence tomography in canaloplasty

      Feasibility of microscope-integrated swept-source optical coherence tomography in canaloplasty

      Background: Several researchers have used commercial microscope-integrated optical coherence tomography (OCT) systems in glaucoma surgery, including ab interno trabeculectomy and canaloplasty. However, the 840 nm wavelength light source of the OCT systems is not ideal for imaging the anterior chamber angle structures because of its limited penetration. We evaluated the potential value of a microscope-integrated swept-source OCT system with a 1,310 nm center-wavelength light in canaloplasty for glaucoma. Methods: Sixteen porcine eyes were used to simulate canaloplasty. The critical surgical steps were monitored using a prototype microscope-integrated OCT system with a 1,310 nm light source and a high ...

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    21. Analysis of the Choroid and Its Relationship with the Outer Retina in Patients with Diabetes Mellitus Using Binarization Techniques Based on Spectral-Domain Optical Coherence Tomography

      Analysis of the Choroid and Its Relationship with the Outer Retina in Patients with Diabetes Mellitus Using Binarization Techniques Based on Spectral-Domain Optical Coherence Tomography

      (1) Background : We aimed to reveal the relationship between the choroid and the outer retina with optical coherence tomography (OCT) in patients with diabetes mellitus (DM) with mild or no diabetic retinopathy (DR) in order to find early biomarkers for progressing retinopathy. (2) Methods : We performed a prospective study including 61 eyes of patients with type 1 or type 2 DM and 36 eyes of healthy controls. All subjects were imaged with Spectralis OCT. The choroid was assesseed using enhanced depth imaging OCT (EDI-OCT). Binarization of subfoveal choroidal images was done with public domain software, ImageJ (version 1.53a; National ...

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