1. Articles in category: Ophthalmology

    553-576 of 6600 « 1 2 ... 21 22 23 24 25 26 27 ... 273 274 275 »
    1. Optical coherence tomography appears valuable for tracking MS patients over time

      Optical coherence tomography appears valuable for tracking MS patients over time

      Retinal changes over time mirror global central nervous system processes in patients with multiple sclerosis, according to findings from a longitudinal study comparing optical coherence tomography and magnetic resonance imaging findings. The results validate optical coherence tomography (OCT) measures for both clinical monitoring of patients, and as an outcome measure in clinical trials, and could have implications that reach beyond MS, Dr. Shiv Saidha said at the joint meeting of the European and Americas committees for Treatment and Research in Multiple Sclerosis. In 107 multiple sclerosis (MS) patients with a mean age of 44 years and median disease duration of ...

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    2. Fully automated detection of diabetic macular edema and dry age-related macular degeneration from optical coherence tomography images

      Fully automated detection of diabetic macular edema and dry age-related macular degeneration from optical coherence tomography images

      We present a novel fully automated algorithm for the detection of retinal diseases via optical coherence tomography (OCT) imaging. Our algorithm utilizes multiscale histograms of oriented gradient descriptors as feature vectors of a support vector machine based classifier. The spectral domain OCT data sets used for cross-validation consisted of volumetric scans acquired from 45 subjects: 15 normal subjects, 15 patients with dry age-related macular degeneration (AMD), and 15 patients with diabetic macular edema (DME). Our classifier correctly identified 100% of cases with AMD, 100% cases with DME, and 86.67% cases of normal subjects. This algorithm is a potentially impactful ...

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    3. Bioptigen Introduces Deep Imaging OCT System for Contact Lens Metrology

      Bioptigen Introduces Deep Imaging OCT System for Contact Lens Metrology

      Bioptigen announced today the availability of a newly developed deep imaging OCT system for the optical device metrology and pre-clinical ophthalmic research markets. The Envisu S4410 SDOCT for Contact Lens Metrology is designed for non-destructive, non-contact, full immersion measurements for standard and high complexity contact lens, IOL structures, and donor tissues. The metrology system allows imaging of a complete contact lens immersed in a hydration bath (saline), automated segmentation of anterior and posterior surfaces, and quantification of curvatures across both surfaces. The system delivers 5 um axial pixel resolution, 11 mm scan depth in saline, and a full 20mm lateral ...

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      Mentions: Bioptigen
    4. Automated retinal layers segmentation in SD-OCT images using dual-gradient and spatial correlation smoothness constraint

      Automated retinal layers segmentation in SD-OCT images using dual-gradient and spatial correlation smoothness constraint

      Automatic segmentation of retinal layers in spectral domain optical coherence tomography (SD-OCT) images plays a vital role in the quantitative assessment of retinal disease, because it provides detailed information which is hard to process manually. A number of algorithms to automatically segment retinal layers have been developed; however, accurate edge detection is challenging. We developed an automatic algorithm for segmenting retinal layers based on dual-gradient and spatial correlation smoothness constraint. The proposed algorithm utilizes a customized edge flow to produce the edge map and a convolution operator to obtain local gradient map in the axial direction. A valid search region ...

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    5. Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      Study of cystoid macular edema by optical coherent tomography following uneventful cataract surgery

      The objective of this paper is to study the incidence of cystoid macular edema (CME) using optical coherence tomography (OCT) following uneventful small incision cataract surgery (SICS) and phacoemulsification. This was a descriptive, prospective study where 200 patients undergoing cataract surgery were randomly divided into two groups over a period of 1 year. Patients undergoing uneventful small incision cataract surgery were included in group I and patient undergoing uneventful phacoemulsification were included in group II, with 100 patients in each group. Preoperative assessment included best corrected visual acuity, detailed anterior segment and posterior segment evaluation, and intraocular pressure measurement. Macular ...

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    6. Retinal Regeneration Following OCT-guided Laser Injury in Zebrafish

      Retinal Regeneration Following OCT-guided Laser Injury in Zebrafish

      Purpose: Establish a focal injury/regeneration model in zebrafish using laser photocoagulation guided by optical coherence tomography (OCT). Methods: Adult zebrafish were imaged by OCT and confocal scanning laser ophthalmoscopy (cSLO) in room air through a contact lens. Using a beam combiner, 532nm laser photocoagulation was applied using the OCT C-scan image for targeting. Laser spots of 42-47mW were delivered to the retina. At multiple intervals post-injury, fish were imaged using both OCT and cSLO to follow the progression of each lesion. Histologic sections and TUNEL staining were performed to monitor the injury response. Results: Round lesions (26057 ± 621μm2 ...

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    7. SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IN THE EVALUATION AND MANAGEMENT OF INFECTIOUS RETINITIS

      SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY IN THE EVALUATION AND MANAGEMENT OF INFECTIOUS RETINITIS

      Purpose: To describe spectral domain optical coherence tomography (SD-OCT) findings of infectious retinitis, including affected layer of retinal involvement, changes at the vitreoretinal interface, and response to therapy. Methods: Observational case series. A retrospective review of five patients with infectious retinitis: one with toxoplasmosis, three with herpetic retinitis secondary to cytomegalovirus, and one with herpetic retinitis secondary to varicella zoster virus. Each patient underwent a complete ophthalmologic examination, fundus photography, and SD-OCT imaging (Heidelberg Spectralis; Heidelberg Engineering, Heidelberg, Germany) of the affected retina at the initial visit with serial fundus photography and SD-OCT imaging at follow-up visits. Approval was obtained ...

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    8. OCT 3-D surface topography of isolated human crystalline lenses

      OCT 3-D surface topography of isolated human crystalline lenses

      Quantitative 3-D Optical Coherence Tomography was used to measure surface topography of 36 isolated human lenses, and to evaluate the relationship between anterior and posterior lens surface shape and their changes with age. All lens surfaces were fitted to 6th order Zernike polynomials. Astigmatism was the predominant surface aberration in anterior and posterior lens surfaces (accounting for ~55% and ~63% of the variance respectively), followed by spherical terms, coma, trefoil and tetrafoil. The amount of anterior and posterior surface astigmatism did not vary significantly with age. The relative angle between anterior and posterior surface astigmatism axes was on average 36 ...

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    9. Fluorescein angiography versus spectral domain optical coherence tomography in idiopathic juxtafoveal retinal telangiectasia

      Fluorescein angiography versus spectral domain optical coherence tomography in idiopathic juxtafoveal retinal telangiectasia

      Dear Editor, We thank Dr. Singh and colleagues for their interest in our article, titled “Diagnosis of subretinal neovascularization associated with idiopathic juxtafoveal retinal telangiectasia—fluorescein angiography versus spectral-domain optical coherence tomography” [ 1 ]. We appreciate their concerns and here are the point-to-point responses to their comments. Comment 1. Color fundus photo has low sensitivity in detecting SRNV secondary to IJRT type 2A. This implies that a number of SRNV would be missed on color fundus photos. However, in this study, a color fundus photo is being used as a reference for presence or absence of SRNV, and this would result ...

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    10. Optical Coherence Tomography of Bilateral Nanophthalmos with Macular Folds and High Hyperopia

      Optical Coherence Tomography of Bilateral Nanophthalmos with Macular Folds and High Hyperopia

      There is a conflict about the content of the macular folds in nanophthalmic eyes in the literature. Our study clearly demonstrated that papillomacular folds seen in nanophthalmos or posterior microphthalmos were only composed of neurosensory retina without involvement of retinal pigment epithelium and choroid. Observations. This is a report of two consecutive nanophthalmic patients with macular folds at Maltepe University School of Medicine, Department of Ophthalmology, from January to June 2012. Anterior segment dimensions were near normal. The axial lengths of the eyes were short with markedly shortened posterior segment. A macular fold extending from the center of the fovea ...

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    11. Visualization of the ocular pulse in the anterior chamber of the mouse eye in vivo using phase-sensitive optical coherence tomography

      Visualization of the ocular pulse in the anterior chamber of the mouse eye in vivo using phase-sensitive optical coherence tomography

      We report on a phase-based method for accurately measuring the ocular pulse in the anterior chamber in vivo . Using phase-sensitive optical coherence tomography with optimized scanning protocols and equations for compensating bulk motion and environmental vibrations, a high sensitivity of 0.9     μ m / s minimal velocity is demonstrated at a wide detection band of 0 to 380 Hz. The pulsatile relative motion between cornea and crystalline lens in rodents is visualized and quantified. The relative motion is most likely caused by respiration (1.6 Hz) and heartbeat (6.6 Hz). The velocity amplitude of the relative motion is 10.3 ...

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    12. Vessel Labeling in Combined Confocal Scanning Laser Ophthalmoscopy and Optical Coherence Tomography Images: Criteria for Blood Vessel Discrimination

      Vessel Labeling in Combined Confocal Scanning Laser Ophthalmoscopy and Optical Coherence Tomography Images: Criteria for Blood Vessel Discrimination

      Introduction The diagnostic potential of optical coherence tomography (OCT) in neurological diseases is intensively discussed. Besides the sectional view of the retina, modern OCT scanners produce a simultaneous top-view confocal scanning laser ophthalmoscopy (cSLO) image including the option to evaluate retinal vessels. A correct discrimination between arteries and veins (labeling) is vital for detecting vascular differences between healthy subjects and patients. Up to now, criteria for labeling (cSLO) images generated by OCT scanners do not exist. Objective This study reviewed labeling criteria originally developed for color fundus photography (CFP) images. Methods The criteria were modified to reflect the cSLO technique ...

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    13. Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images

      Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images

      Optical coherence tomography is a high resolution, rapid, and noninvasive diagnostic tool for angle closure glaucoma. In this paper, we present a new strategy for the classification of the angle closure glaucoma using morphological shape analysis of the iridocorneal angle. The angle structure configuration is quantified by the following six features: (1) mean of the continuous measurement of the angle opening distance; (2) area of the trapezoidal profile of the iridocorneal angle centered at Schwalbe's line; (3) mean of the iris curvature from the extracted iris image; (4) complex shape descriptor, fractal dimension, to quantify the complexity, or changes ...

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    14. Long-term Assessment of Tilt of Glued Intraocular Lenses An Optical Coherence Tomography Analysis 5 Years after Surgery

      Long-term Assessment of Tilt of Glued Intraocular Lenses  An Optical Coherence Tomography Analysis 5 Years after Surgery

      Purpose Long-term assessment of the optic position of glued transscleral fixated intraocular lens (IOL) with optical coherence tomography (OCT). Design Prospective observational case series. Participants Patients with a minimum 5 years' follow-up after glued IOL surgery were included. Methods Postoperatively, IOL position was examined by anterior segment OCT (Carl Zeiss Meditec) and the scans were analyzed in 2 axes (180°–0° and 270°–90°) using MatLab (Mathworks). Best-corrected visual acuity (BCVA; Snellen's charts), Orbscan, retinoscopy, refraction, and slit-lamp biomicroscopy were performed. Main Outcome Measures The distance between the iris margin and the anterior IOL optic (D1, D2), slope of ...

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    15. Ganglion cell and inner plexiform layer thickness determined by spectral domain optical coherence tomography in patients with brain lesions

      Ganglion cell and inner plexiform layer thickness determined by spectral domain optical coherence tomography in patients with brain lesions

      Purpose To evaluate the thickness of the macular ganglion cell and inner plexiform layer (GCIPL) using spectral domain optical coherence tomography (SD OCT) in patients with brain lesions. Methods This case-control study included 58 healthy subjects and 98 patients with brain lesions confirmed by MRI. GCIPL and peripapillary retinal nerve fiber layer (pRNFL) thicknesses were determined using the Cirrus SD OCT. Area under the receiver operating characteristic curve (AUC) values of pRNFL and GCIPL thickness were used to discriminate patients with brain lesions from normal controls. Results Average GCIPL thickness showed a good correlation with visual field mean deviation (r ...

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    16. Oregon Health & Science University Receives NIH Grant for Functional and Structural Optical Coherence Tomgoraphy for Glaucoma

      Oregon Health & Science University Receives NIH Grant  for Functional and Structural Optical Coherence Tomgoraphy for Glaucoma

      Oregon Health & Science University Receives a 2014 NIH Grant for $734,129 for Functional and Structural Optical Coherence Tomgoraphy for Glaucoma. The principal investigator is David Huang. The program began in 2013 and ends in 2017. Below is a summary of the proposed work. Glaucoma is a leading cause of blindness. Early diagnosis and close monitoring of glaucoma are important because the onset is insidious and the damage is irreversible. Advanced imaging modalities such as optical coherence tomography (OCT) have been used in the past 2 decades to improve the objective evaluation of glaucoma. OCT has higher axial spatial resolution ...

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    17. Oregon Health & Science University Receives 2014 NIH Guiding The Treatment of Anterior Eye Disease with Optical Coherence Tomography

      Oregon Health & Science University Receives 2014 NIH  Guiding The Treatment of Anterior Eye Disease with Optical Coherence Tomography

      Oregon Health & Science University Receives a 2014 NIH Grant for $713,409 for Guiding The Treatment of Anterior Eye Disease with Optical Coherence Tomography. The principal investigator is David Huang. The program began in 2007 and ends in 2016. Below is a summary of the proposed work. Optical coherence tomography (OCT) is a cross-sectional and 3-dimensional (3-D) imaging technology with very fine spatial resolution (5 um). This project develops the methods and software needed for high-precision OCT measurements of the eye to guide implant, laser, and transplant surgeries in the front part of the eye. In the proposed continuation of ...

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    18. Bioptigen Receives NIH Grant for Measuring Choroidal Blood Flow Imaging with Spectral Domain OCT

      Bioptigen Receives NIH Grant  for Measuring Choroidal Blood Flow Imaging with Spectral Domain OCT

      Bioptigen Receives 2014 NIH Grant for $223,583 for Measuring Choroidal Blood Flow Imaging with Spectral Domain OCT. The principal investigator is Eric Buckland. The program began in 2014 and ends in 2015. Below is a summary of the proposed work. Ophthalmic vascular diseases impact millions of Americans. Age-related macular degeneration and diabetic retinopathy are the two major diseases with a well- known vascular factor. The role of the vascular system in glaucoma and retinopathy of prematurity is more insidious. The vascular theory of glaucoma suggests that the blood supply to the eye is a contributory factor in glaucoma. Advanced ...

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    19. Stable Registration of Pathological 3D SD-OCT Scans using Retinal Vessels

      Stable Registration of Pathological 3D SD-OCT Scans using Retinal Vessels

      We propose a multiple scanner vendor registration method for pathological retinal 3D spectral domain optical coherence tomography volumes based on Myronenko’s Coherent Point Drift and our automated vessel shadow segmentation. Coherent point drift is applied to the segmented retinal vessel point sets used as landmarks to generate the registration parameters required. In contrast to other registration methods, our solution incorporates a landmark detection and extraction method that specifically limits the extraction of false positives and a registration method capable of handling any such noise in the landmark point sets. Our experiments show modified Hausdorff distance is reduced by a ...

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    20. Registration of SD-OCT en-face images with color fundus photographs based on local patch matching

      Registration of SD-OCT en-face images with color fundus  photographs based on local patch matching

      Registration of multi-modal retinal images is very significant to integrate information gained from different modalities for a reliable diagnosis of retinal diseases by ophthalmologists. However, accurate image registration is a challenging, we propose an algorithm for registration of summed-voxel projection images (SVPIs) with color fundus photographs (CFPs) based on local patch matching. SVPIs are evenly split into 16 local image blocks for extracting matching point pairs by searching local maximization of the similarity function. These matching point pairs are used for a coarse registration and then a search region of feature matching points is redefined for a more accurate registration ...

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    21. An Automated Framework of Inner Segment/Outer Segment Defect Detection for Retinal SD-OCT Images

      An Automated Framework of Inner Segment/Outer  Segment Defect Detection for Retinal SD-OCT Images

      The integrity of inner segment/outer segment (IS/OS) has high correlation with lower visual acuity in patients suffering from blunt trauma. An automated 3D IS/OS defect detection method based on the SD-OCT images was proposed. First, 11 surfaces were automatically segmented using the multiscale 3D graph-search approach. Second, the sub-volumes between surface 7 and 8 containing IS/OS region around the fovea (diameter of 1mm) were extracted and flattened based on the segmented retinal pigment epithelium layer. Third, 5 kinds of texture based features were extracted for each voxel. A KNN classifier was trained and each voxel was ...

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    22. Comparison of Retinal Thickness Measurements of Normal Eyes between Topcon Algorithm and a Graph Based Algorithm

      Comparison of Retinal Thickness Measurements of  Normal Eyes between Topcon Algorithm and a Graph  Based Algorithm

      To assess the agreement between Topcon built-in algorithm and our developed graph based algorithm, the retinal thickness of 9-sectors on an Early Treatment of Diabetic Retinopathy Study(ETDRS) chart measurements for normal subjects was compared. A total of fifty eyes were enrolled in this study. The overall and sectoral thickness on ETDRS chart were calculated using Topcon built-in algorithm and our developed three-dimensional graph based algorithm. Correlation analysis and agreement analysis were performed between the commercial algorithm and our algorithm. A high degree of correlation was found between the results obtained from the two methods was from 0.856 to ...

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