1. Articles in category: Ophthalmology

    577-600 of 7896 « 1 2 ... 22 23 24 25 26 27 28 ... 327 328 329 »
    1. En-face optical coherence tomography angiography of neovascularization elsewhere in hemicentral retinal vein occlusion

      En-face optical coherence tomography angiography of neovascularization elsewhere in hemicentral retinal vein occlusion

      Purpose: To evaluate how the growth of neovascularization elsewhere (NVE) was delineated in an eye with hemicentral retinal vein occlusion (CRVO) using optical coherence tomography (OCT) angiography. Patients and methods: We examined a 64-year-old man diagnosed with hemi-CRVO. The area around the occluded vein was scanned using a spectral-domain OCT device (RTVue XR Avanti). Blood flow was detected using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm. Color fundus photography, fluorescein angiography (FA), and OCT angiography examinations were performed at the first visit and at 3 and 6 months postpresentation. Results: At the first visit, FA revealed delayed retinal venous filling and ...

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    2. Effect of image registration on longitudinal analysis of retinal nerve fiber layer thickness of non-human primates using Optical Coherence Tomography (OCT)

      Effect of image registration on longitudinal analysis of retinal nerve fiber layer thickness of non-human primates using Optical Coherence Tomography (OCT)

      Background In this paper we determined the benefits of image registration on estimating longitudinal retinal nerve fiber layer thickness (RNFLT) changes. Methods RNFLT maps around the optic nerve head (ONH) of healthy primate eyes were measured using Optical Coherence Tomography (OCT) weekly for 30 weeks. One automatic algorithm based on mutual information (MI) and the other semi-automatic algorithm based on log-polar transform cross-correlation using manually segmented blood vessels (LPCC_MSBV), were used to register retinal maps longitudinally. We compared the precision and recall between manually segmented image pairs for the two algorithms using a linear mixed effects model. Results We found ...

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    3. Relationship between Retinal Blood Flow and Arterial Oxygen

      Relationship between Retinal Blood Flow and Arterial Oxygen

      Retinal blood flow (RBF) increases in response to a reduction in oxygen (hypoxia), but decreases in response to increased oxygen (hyperoxia). However, the relationship between blood flow and the arterial partial pressure of oxygen has not been quantified and modeled in the retina in particular the vascular reserve and resting tonus of the vessels. The objective of this study was to determine the limitations of the retinal vasculature by modeling the relationship between RBF and oxygen. Retinal vascular responses were measured in 13 subjects for 8 different blood gas conditions, with the end-tidal partial pressure of oxygen (P ET O ...

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    4. Argus II retinal prosthesis malrotation and repositioning with intraoperative optical coherence tomography in a posterior staphyloma

      Argus II retinal prosthesis malrotation and repositioning with intraoperative optical coherence tomography in a posterior staphyloma

      Introduction: The Argus II retinal prosthesis may improve visual function in patients with severe vision loss from retinitis pigmentosa. Optimal centration of the electrode array over the macula is important to achieve optimal visual results. Argus tack malrotation is a novel entity that may be encountered during placement, especially in patients with posterior staphyloma. Methods: Retrospective case review. Results: During tacking of the electronics array a clockwise rotation occurred resulting in malposition. We hypothesize this was secondary to undue rotation or posterior pressure applied during tack insertion in conjunction with placement over a previously unrecognized posterior staphyloma. Intraoperative optical coherence ...

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    5. Systematic Evaluation of Optical Coherence Tomography Angiography in Retinal Vein Occlusion

      Systematic Evaluation of Optical Coherence Tomography Angiography in Retinal Vein Occlusion

      Purpose To evaluate the clinical utility of optical coherence tomography angiography (OCTA) in patients with retinal vein occlusion (RVO), and to systematically compare OCTA images with changes seen on color fundus photography and fluorescein angiography (FA). Design Reliability analysis. Methods 81 eyes of 76 patients with a history of RVO (branch, central or hemi-central), both acute and chronic, underwent OCTA (AngioVue™, Optovue, Inc. Fremont, CA, USA) and color fundus photography. In 29 eyes, data were compared to FA imaging. Comparative and multimodal analysis of the three imaging procedures were performed. Results We identified good agreement between FA and OCTA scans ...

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    6. Corneal epithelial thickness measured by Fourier-domain optical coherence tomography

      Corneal epithelial thickness measured by Fourier-domain optical coherence tomography

      Purpose To characterize the corneal epithelial thickness profile with Fourier-domain optical coherence tomography (FD-OCT). Methods Epithelial thickness measurements were obtained by FD-OCT within the central 6-mm zone of the cornea in all subjects who were divided into groups of A (0–20 years), B (21–40 years), C (41–60 years), and D (> 60 years) according to age. Profile maps of the central, average, minimum, maximum, standard deviation, every ring, and radiate area of corneal epithelial thickness were plotted. Differences of the epithelial thickness values at the central cornea and peripheral locations were calculated. Results The mean epithelial thickness was ...

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    7. The Repeatability Assessment of Three-Dimensional Capsule-Intraocular Lens Complex Measurements by Means of High-Speed Swept-Source Optical Coherence Tomography

      The Repeatability Assessment of Three-Dimensional Capsule-Intraocular Lens Complex Measurements by Means of High-Speed Swept-Source Optical Coherence Tomography

      Purpose To rebuild the three-dimensional (3-D) model of the anterior segment by high-speed swept-source optical coherence tomography (SSOCT) and evaluate the repeatability of measurement for the parameters of capsule-intraocular lens (C-IOL) complex. Methods Twenty-two pseudophakic eyes from 22 patients were enrolled. Three continuous SSOCT measurements were performed in all eyes and the tomograms obtained were used for 3-D reconstruction. The output data were used to evaluate the measurement repeatability. The parameters included postoperative aqueous depth (PAD), the area and diameter of the anterior capsule opening (Area and D), IOL tilt (IOL-T), horizontal, vertical, and space decentration of the IOL, anterior ...

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      Mentions: Giacomo Savini
    8. Focusing algorithm in OCT-only systems

      Focusing algorithm in OCT-only systems

      In an OCT system, the autocorrelation signal depends only on the strength of the signal in the object arm scattered back from a patient's retina and is a result of different reflections from different layers of the retina interfering with each other. The strength of the autocorrelation signal depends on how well focused the system is. Normally the autocorrelation signal is treated as noise. However by removing the reference path signal, the autocorrelation signal is easily measured and analyzed. The optimal focus can the then be found by adjusting the focus value until the autocorrelation signal is maximized.

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    9. Ellipsoid zone on optical coherence tomography: a review

      Ellipsoid zone on optical coherence tomography: a review

      Emergence of the high-resolution optical coherence tomography has allowed better delineation of retinal layers and many of the anatomical correlations of these layers have now been agreed upon. However some anatomical correlates still remain contentious, such as the second hyper-reflective band which is now termed ellipsoid zone. Despite the lack of consensus of the actual origin of the ellipsoid zone, there has been much interest in evaluating its integrity and intensity in different disease processes. This review paper aims to provide an overview of the ellipsoid zone and its clinical and research applications.

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    10. Significant changes detection in the follow-up of Retinal Pathologies through computer analysis of Optical Coherence Tomgraphy

      Significant changes detection in the follow-up of Retinal Pathologies through computer analysis of Optical Coherence Tomgraphy

      Recently, Optical Coherence Tomograhy (OCT) is widely used to investigate retinal pathologies.Quantitative methods are needed to support qualitative evaluation carried on by medical specialists. Besides retinal thickness measurement, tomographic imaging allows to study macula morphology and tissue structure of retinal cellular layers. Pathological conditions are expected to alter this tissue appearance. Therefore, in the present work, image texture analysis is used to differenziate normal retinas from pathological ones as well as to detect significant changes in follow-up studies. Classical second order statistics, i.e. co-occurrence matrices, and a recent method, known as Local Binary Pattern (LBP), are applied to ...

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    11. Three-dimensional spectral domain optical coherence tomography and light microscopy of an intravitreal parasite

      Three-dimensional spectral domain optical coherence tomography and light microscopy of an intravitreal parasite

      Background Various imaging modalities play a role in diagnosing parasitic infections of the eye. We describe the spectral domain optical coherence tomography (SD-OCT) findings of an intravitreal parasite with subsequent evaluation by light microscopy. Findings This is a case report of a 37-year-old Ecuadorian man who presented with uveitic glaucoma and a new floater in his left eye for 1 week’s duration. Full ophthalmic examination revealed an intravitreal parasite. Color fundus photography, fluorescein angiography (FA), ocular ultrasonography (US), and SD-OCT were performed. The parasite was removed via 23-gauge pars plana vitrectomy and sent to pathology for evaluation. Color fundus ...

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    12. Detection of diabetic macular oedema: validation of optical coherence tomography using both foveal thickness and intraretinal fluid

      Detection of diabetic macular oedema: validation of optical coherence tomography using both foveal thickness and intraretinal fluid

      No studies have yet evaluated jointly central foveal thickness (CFT) and the presence of intraretinal fluid (PIF) to diagnose diabetic macular oedema (DMO) using optic coherence tomography (OCT). We performed a cross-sectional observational study to validate OCT for the diagnosis of DMO using both CFT and PIF assessed by OCT (3D OCT-1 Maestro). A sample of 277 eyes from primary care diabetic patients was assessed in a Spanish region in 2014. Outcome: DMO diagnosed by stereoscopic mydriatic fundoscopy. OCT was used to measure CFT and PIF. A binary logistic regression model was constructed to predict the outcome using CFT and ...

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    13. Structural dissociation of optic disc margin components with optic disc tilting: a spectral domain optical coherence tomography study

      Structural dissociation of optic disc margin components with optic disc tilting: a spectral domain optical coherence tomography study

      Purpose To investigate the dissociation of the Bruch’s membrane opening (BMO) from the scleral canal opening (SO) of the optic disc. Methods In this prospective, cross-sectional, observational study, 101 eyes from 101 patients or suspected subjects of primary open angle glaucoma were included. Enhanced depth imaging spectral domain optical coherence tomography images along the long axis of the optic disc were used to visualize better the deep structures around the optic disc on both the temporal and nasal sides. The distances between the BMO and SO were measured at the temporal and nasal sides of the optic disc, and ...

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    14. Retinal involvement in amyotrophic lateral sclerosis: a study with optical coherence tomography and diffusion tensor imaging

      Retinal involvement in amyotrophic lateral sclerosis: a study with optical coherence tomography and diffusion tensor imaging

      Although motor neuron degeneration is the predominant feature in ALS, recent data point to a more widespread pathology also comprising non-motor symptoms. Retinal thinning has been reported in a variety of neurodegenerative conditions. Yet, studies of retinal involvement in ALS are sparse and results are heterogeneous. We studied retinal alterations in ALS using a systematic approach combining Optical Coherence Tomography (OCT), Diffusion Tensor Imaging (DTI) and clinical phenotyping. We hypothesized that selective changes of specific retinal layers may be a reflection of overall neurodegeneration as measured by DTI. Spectral domain OCT images were analyzed to calculate the average thickness of ...

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    15. SHORT-TERM FLUCTUATION OF MACULAR EDEMA IN A PATIENT DIAGNOSED EARLY WITH IDIOPATHIC MACULAR TELANGIECTASIA TYPE 1: FOLLOW-UP WITH SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

      SHORT-TERM FLUCTUATION OF MACULAR EDEMA IN A PATIENT DIAGNOSED EARLY WITH IDIOPATHIC MACULAR TELANGIECTASIA TYPE 1: FOLLOW-UP WITH SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY

      Purpose: To present a case of idiopathic macular telangiectasia Type 1, diagnosed at early stages and its close monitoring through spectral domain optical coherence tomography. Methods: Case report. Results: A case is presented of a 43-year-old man with blurred vision in his right eye and no further symptoms. The patient did not have any history of ophthalmic disease. Imaging test with fluorescein angiography confirmed a diagnosis of idiopathic macular telangiectasia Type 1. Conclusion: During a close follow-up period of 6 months, spectral domain optical coherence tomography demonstrated considerable fluctuations regarding his central retinal thickness (macular edema), presence of lipid exudates ...

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    16. MULTIMODAL IMAGING OF A FAMILY WITH SPINOCEREBELLAR ATAXIA TYPE 7 DEMONSTRATING PHENOTYPIC VARIATION AND PROGRESSION OF RETINAL DEGENERATION

      MULTIMODAL IMAGING OF A FAMILY WITH SPINOCEREBELLAR ATAXIA TYPE 7 DEMONSTRATING PHENOTYPIC VARIATION AND PROGRESSION OF RETINAL DEGENERATION

      Purpose: To report the variability and progression of clinical presentation in three family members with spinocerebellar ataxia Type 7 including early recognizable features on retinal imaging and magnetic resonance imaging. Methods: Retrospective case series. Results: The proband, Patient 1 (mother) presented at age 26 with light perception vision. Initial examination was significant for optic disc pallor, vascular attenuation, and central macular atrophy. Two years later, her vision declined to no light perception, and fundus examination demonstrated marked progression of macular atrophy and peripheral bone spicule formation. Seven years after the onset of vision loss, neurologic examination demonstrated ataxia, dysarthria, and ...

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      Mentions: Emory University
    17. Birefringence imaging of posterior eye by multi-functional Jones matrix optical coherence tomography

      Birefringence imaging of posterior eye by multi-functional Jones matrix optical coherence tomography

      A clinical grade prototype of posterior multifunctional Jones matrix optical coherence tomography (JM-OCT) is presented. This JM-OCT visualized depth-localized birefringence in addition to conventional cumulative phase retardation imaging through local Jones matrix analysis. In addition, it simultaneously provides a sensitivity enhanced scattering OCT, a quantitative polarization uniformity contrast, and OCT-based angiography. The probe beam is at 1- μ m wavelength band. The measurement speed and the depth-resolution were 100,000 A-lines/s, and 6.6 μ m in tissue, respectively. Normal and pathologic eyes are examined and several clinical features are revealed, which includes high birefringence in the choroid and lamina cribrosa ...

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    18. Classification of image artefacts in optical coherence tomography angiography of the choroid in macular diseases

      Classification of image artefacts in optical coherence tomography angiography of the choroid in macular diseases

      Background To evaluate and classify image artefacts in optical coherence tomography (OCT) angiography (OCTA) of the choroid in a group of patients with macular diseases. Design Retrospective observational study. Participants 5 patients with age-related macular degeneration, 3 with central serous retinopathy, 1 with polypoidal choroidal vasculopathy and 1 with multiple evanescent white dot syndrome. Methods OCTA and OCT reflectivity (OCTR) maps were reviewed along with their fluorescein angiography and indocyanine green angiography. 60 OCTA images (20 outer retina, 20 Sattler and 20 Haller layers) were graded for image artefacts by 2 examiners independently. Main Outcome Measures OCTA artefacts and their ...

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    19. Primary Acquired Melanosis: Clinical, Histopathologic and Optical Coherence Tomographic Correlation

      Primary Acquired Melanosis: Clinical, Histopathologic and Optical Coherence Tomographic Correlation

      Aim: To assess the use of anterior segment optical coherence tomography (OCT) as an adjuvant diagnostic tool in primary acquired melanosis (PAM) by correlating clinical, histopathologic and anterior segment OCT findings. Methods: Twenty-four patients (24 eyes) with PAM of the conjunctiva, cornea or both were imaged with an anterior segment OCT device (RTVue, model-RT100; Optovue Inc., Fremont, Calif., USA). Results: Histopathologic diagnosis following excisional or incisional biopsy was confirmed in 13 out of 24 patients (54.6%). OCT images showed a characteristic uniformly thick basal epithelial hyperreflective band (about 20 μm thick) and normal thickness of the overlying epithelial layer ...

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    20. Change of Retinal Nerve Layer Thickness in Non-Arteritic Anterior Ischemic Optic Neuropathy Revealed by Fourier Domain Optical Coherence Tomography

      Change of Retinal Nerve Layer Thickness in Non-Arteritic Anterior Ischemic Optic Neuropathy Revealed by Fourier Domain Optical Coherence Tomography

      Purpose : To examine the changes of non-arteritic anterior ischemic optic neuropathy (NAION) by serial morphometry using Fourier domain optical coherence tomography (FD-OCT). Materials and methods : Retrospective study in patients with newly diagnosed NAION ( n =33, all unilateral) and controls ( n =75 unilateral NAION patients with full contralateral eye vision) who underwent FD-OCT of the optic disk, optic nerve head (ONH), and macula within 1 week of onset and again 1, 3, 6, and 12 months later. The patients showed no improvement in vision during follow-up. Results : Within 1 week of onset, all NAION eyes exhibited severe ONH fiber crowding and ...

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      Mentions: Yan Li
    21. Correlation of Vitreous Vascular Endothelial Growth Factor and Uric Acid Concentration Using Optical Coherence Tomography in Diabetic Macular Edema

      Correlation of Vitreous Vascular Endothelial Growth Factor and Uric Acid Concentration Using Optical Coherence Tomography in Diabetic Macular Edema

      Purpose . We investigated two factors linked to diabetic macular edema (DME), vitreous and serum levels of vascular endothelial growth factor (VEGF) and uric acid (UA) in patients with DME, and compared the results with changes in optical coherence tomography (OCT) and visual acuity (VA). Methods . A prospective study of 29 eyes, 16 cystoid DME and nonproliferative diabetic retinopathy (DR) and 13 nondiabetic controls. Biochemical analysis of vitreous and serum samples was performed and OCT scans were graded according to central retinal thickness (CRT), cube volume (CV), cube average thickness (CAT), and serous retinal detachment (SRD). Results . In DME group, intravitreal ...

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    22. Effects of Implantable Collamer Lens V4c placement on iridocorneal angle measurements by Fourier domain optical coherence tomography

      Effects of Implantable Collamer Lens V4c placement on iridocorneal angle measurements by Fourier domain optical coherence tomography

      Purpose To assess by Fourier domain optical coherence tomography (FD-OCT) changes produced in iridocorneal angle measurements in patients undergoing Visian Implantable Collamer Lens ® (ICL) V4c (STAAR Surgical AG) placement. Design Prospective interventional case series. Methods In 50 eyes of 25 myopic subjects consecutively scheduled for ICL implant, FD-OCT (RTVue ® , Optovue Inc.) iridocorneal angle measurements were made before and 1 and 3 months after surgery. Trabecular-iris angle (TIA), and angle opening distance 500 μm anterior to the scleral spur (AOD 500 ) were compared among the quadrants nasal, temporal and inferior, and correlations with ocular variables including lens vault were examined. Results ...

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    23. Macular Bruch’s Membrane Holes in Choroidal Neovascularization-Related Myopic Macular Atrophy by Swept-Source Optical Coherence Tomography

      Macular Bruch’s Membrane Holes in Choroidal Neovascularization-Related Myopic Macular Atrophy by Swept-Source Optical Coherence Tomography

      Purpose To determine frequency and associations of macular Bruch’s membrane defects in the region of macular atrophy developing after the onset of myopic choroidal neovascularization (CNV). Design Retrospective observational case series. Methods The study included all patients who were consecutively examined for high myopia (axial length ≥26.5mm) and CNV-related macular atrophy in the study period from June to July 2015. The patients underwent a comprehensive ophthalmologic examination including swept-source optical coherence tomography (OCT) of the macula. Main outcome measures were macular Bruch’s membrane defects. Results Out of 33 eyes (28 patients) with myopic CNV-related macular atrophy, 25 ...

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    24. Optical coherence tomography platforms and parameters for glaucoma diagnosis and progression

      Optical coherence tomography platforms and parameters for glaucoma diagnosis and progression

      Purpose of review: With the rapid adoption of spectral domain optical coherence tomography (SDOCT) in clinical practice and the recent advances in software technology, there is a need for a review of the literature on glaucoma detection and progression analysis algorithms designed for the commercially available instruments. Recent findings: Peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness, including segmental macular thickness calculation algorithms, have been demonstrated to be repeatable and reproducible, and have a high degree of diagnostic sensitivity and specificity in discriminating between healthy and glaucomatous eyes across the glaucoma continuum. Newer software capabilities such as glaucoma ...

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