1. Articles in category: Ophthalmology

    553-576 of 9881 « 1 2 ... 21 22 23 24 25 26 27 ... 410 411 412 »
    1. Acquistion and analysis techniques for improved outcomes in optical coherence tomography angiography

      Acquistion and analysis techniques for improved outcomes in optical coherence tomography angiography
      Abstract

      Methods for improved acquisition and processing of optical coherence tomography (OCT) angiography data are presented. One embodiment involves improving the acquisition of the data by evaluating the quality of different portions of the data to identify sections having non-uniform acquisition parameters or non-uniformities due to opacities in the eye such as floaters. The identified sections can then be brought to the attention of the user or automatically reacquired. In another embodiment, segmentation of layers in the retina includes both structural and flow information derived from motion contrast processing. In a further embodiment, the health of the eye is evaluating ...

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    2. EVALUATION OF MACULAR ISCHEMIA IN EYES WITH CENTRAL RETINAL VEIN OCCLUSION: An Optical Coherence Tomography Angiography Study

      EVALUATION OF MACULAR ISCHEMIA IN EYES WITH CENTRAL RETINAL VEIN OCCLUSION: An Optical Coherence Tomography Angiography Study

      Purpose: To quantitatively assess macular perfusion status using optical coherence tomography angiography in eyes with aflibercept-treated central retinal vein occlusion and resolved macular edema and to investigate the impact of macular morphology and perfusion status on visual function. Methods: This prospective consecutive case series included 23 patients with central retinal vein occlusion. All patients received intravitreal aflibercept injections before analysis. Visual acuity, macular sensitivity, and the macular nonperfusion area (NPA) were evaluated in eyes without macular edema. The macular NPA was evaluated by optical coherence tomography angiography using 3 mm x 3 mm images of the macula. Foveal ellipsoid zone ...

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    3. Author Response: Biomechanical Responses of Lamina Cribrosa to Intraocular Pressure Change Assessed by Optical Coherence Tomography in Glaucoma Eyes

      Author Response: Biomechanical Responses of Lamina Cribrosa to Intraocular Pressure Change Assessed by Optical Coherence Tomography in Glaucoma Eyes

      Our recent publication 1 noted several features of change in anterior lamina depth (ALD) with change in intraocular pressure (IOP) in glaucoma patients. ALD changed more in the lower ranges of IOP than at higher ranges, which represents the expected increased stiffening of biomaterials in regions of higher stress. Some eyes exhibited movement of the lamina out of the eye at lower IOP—a behavior that is more likely when the peripapillary sclera is more compliant. This was more common in eyes with less glaucoma damage. The regions of the lamina that moved more were in its vertical poles, above ...

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    4. Biomechanical Responses of Lamina Cribrosa to Intraocular Pressure Change Assessed by Optical Coherence Tomography in Glaucoma Eyes

      Biomechanical Responses of Lamina Cribrosa to Intraocular Pressure Change Assessed by Optical Coherence Tomography in Glaucoma Eyes

      We read with great interest the paper by Quigley et al. 1 investigating the change in anterior lamina cribrosa depth (LCD) before and after several intraocular pressure (IOP)-lowering procedures. They found that the LC can move either anteriorly or posteriorly with IOP decrease, and this change was greater with lower IOP. Quantitative assessment of LCD depends on the reference plane from which the measurements are made, and it is significantly influenced by choroidal thickness (CT) when a Bruch's membrane opening (BMO) reference plane is used. 2 , 3 In the study by Quigley et al., 1 the anterior LCD ...

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    5. The Retinal Atlas, 2nd Edition

      The Retinal Atlas, 2nd Edition

      With more than 5,000 images, a unique page layout, and comprehensive illustrations of the entire spectrum of vitreous, retina, and macula disorders, The Retinal Atlas, 2nd Edition, is an indispensable reference for retina specialists and comprehensive ophthalmologists as well as residents and fellows in training. For this edition, an expanded author team made up of Drs. K. Bailey Freund, David Sarraf, William F. Mieler, and Lawrence A. Yannuzzi, each an expert in retinal research and imaging, provide definitive up-to-date perspectives in this rapidly advancing field. This award-winning title has been thoroughly updated with new images with multimodal illustrations, new ...

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    6. What you should know about OCT – part 2

      What you should know about OCT – part 2

      Following on from Part 1 of this series, which looked at macular scan interpretation, this article will review OCT disc analysis for glaucoma detection and monitoring. Background In 2013, the number of people with glaucoma worldwide was estimated to be 64.3 million, with this number predicted to increase to 76 million by 2020.1 Without timely diagnosis and referral for treatment, the incidence of bilateral blindness secondary to glaucoma will also rise. Currently, identification of glaucoma in primary eye care relies upon the classic triad of optic disc assessment, measurement of IOP and visual field evaluation. However, a survey ...

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    7. Projection-Resolved Optical Coherence Tomography Angiography of Macular Retinal Circulation in Glaucoma

      Projection-Resolved Optical Coherence Tomography Angiography of Macular Retinal Circulation in Glaucoma

      Purpose To detect macular perfusion defects in glaucoma using projection-resolved optical coherence tomography (OCT) angiography. Design Prospective observation study. Participants A total of 30 perimetric glaucoma and 30 age-matched normal participants were included. Methods One eye of each participant was imaged using 6 × 6–mm macular OCT angiography (OCTA) scan pattern by 70-kHz 840-nm spectral-domain OCT. Flow signal was calculated by the split-spectrum amplitude-decorrelation angiography algorithm. A projection-resolved OCTA (PR-OCTA) algorithm was used to remove flow projection artifacts. Four en face OCTA slabs were analyzed: the superficial vascular complex (SVC), intermediate capillary plexus (ICP), deep capillary plexus (DCP), and all-plexus ...

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    8. Normative database for separate inner retinal layers thickness using spectral domain optical coherence tomography in Caucasian population

      Normative database for separate inner retinal layers thickness using spectral domain optical coherence tomography in Caucasian population

      Article Authors Metrics Comments Related Content Abstract Introduction Methods Results Discussion Supporting information Acknowledgments References Reader Comments (0) Media Coverage Figures Abstract Purpose Develop the first normative database of the thickness of every inner retinal layer in the macular area in a healthy, Caucasian population between 18 to 87 years old, using Spectralis Optical Coherence Tomography (OCT). Methods On this transversal, observational study, 300 patients between 18 to 87 years old and without an ophthalmological condition were recruited. Macular OCT scans were performed on all patients (Spectralis OCT, Heidelberg Engineering). An axial length measurement, and keratometry were performed using an ...

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    9. Cross-sectional, observational study of anterior segment parameters using anterior segment optical coherence tomography in North Indian Population

      Cross-sectional, observational study of anterior segment parameters using anterior segment optical coherence tomography in North Indian Population

      Purpose: To study the anterior segment (AS) parameters using AS optical coherence tomography (AS-OCT) in the North Indian population. Methods: A hospital-based, observational, cross-sectional study was conducted over a period of 1 year. It included 251 normal individuals aged 20–70 years. Participants underwent imaging with AS-OCT.Ocular parameters included anterior chamber angle (ACA), iris cross-sectional area (ICSA), iris thickness (IT), and iris curvature (IC). The parameters were measured nasally and temporally for both sexes and different age groups. Results: The mean age of participants was 48.3 ± 13.9 years and 50.6% were men. The ACA decreased with ...

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    10. Effect of phacoemulsification on measurement of retinal nerve fiber layer and optic nerve head parameters using spectral-domain-optical coherence tomography

      Effect of phacoemulsification on measurement of retinal nerve fiber layer and optic nerve head parameters using spectral-domain-optical coherence tomography

      PURPOSE: The purpose of this study is to determine the effect of phacoemulsification cataract extraction on measurement of retinal nerve fiber layer and optic nerve head parameters using spectral domain optical coherence tomography. MATERIAL AND METHODS: A prospective, hospital-based study of 100 patients of 40 years of age and above, with no other ocular morbidity except cataract and planned for phacoemulsification with IOL implantation (SN60WF) at a tertiary centre at AIIMS, New Delhi, India. All patients underwent imaging with Cirrus SD-OCT model 400 and the optic disc cube 200x200 protocol at baseline and at 1 month follow up. Paired sample ...

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    11. Quantitative Analysis of Macular Inner Retinal Layer Using Swept-Source Optical Coherence Tomography in Patients with Optic Tract Syndrome

      Quantitative Analysis of Macular Inner Retinal Layer Using Swept-Source Optical Coherence Tomography in Patients with Optic Tract Syndrome

      Objective . To evaluate macular inner retinal layers using swept-source optical coherence tomography (SS-OCT) in patients with homonymous hemianopia due to optic tract syndrome (OTS). Methods . Sixteen eyes of 8 patients with OTS were studied. The macular retinal nerve fiber layer (mRNFL), ganglion cell layer and inner plexiform layer (GCL + IPL), and mRNFL and GCL + IPL (GCC) were measured by SS-OCT (DRI OCT-1 Atlantis®).The scanned area was divided into eight regions and two hemiretinae. Each retinal thickness of the OTS group was compared with that of the 25 control subjects. Results . The GCC thickness in the ipsilateral eyes was significantly ...

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    12. Intereye asymmetry of optic nerve head parameters and retinal nerve fibre layer thickness in patients with open angle glaucoma detected by spectral domain optical coherence tomography

      Intereye asymmetry of optic nerve head parameters and retinal nerve fibre layer thickness in patients with open angle glaucoma detected by spectral domain optical coherence tomography

      INTRODUCTION. The aim of the study is to evaluate intereye asymmetry of optic nerve head (ONH) parameters and the circumpapillary retinal nerve fibre layer (cpRNFL) thickness in patients with primary open angle glaucoma (POAG). MATERIA LS AND METHODS. The study included 44 patients with POAG in both eyes, 48 binocular glaucoma suspects, and 75 individuals with two healthy eyes. A mixed group of 20 patients had only one eye that met the criteria for POAG. We evaluated the differences between right and left eyes and absolute intereye asymmetry for the individual ONH parameters and cpRNFL thickness, measured by spectral domain ...

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    13. Structural Changes in Optical Coherence Tomography Underlying Spots of Increased Autofluorescence in the Perilesional Zone of Geographic Atrophy

      Structural Changes in Optical Coherence Tomography Underlying Spots of Increased Autofluorescence in the Perilesional Zone of Geographic Atrophy

      Purpose : To investigate structural correlates corresponding to the appearance of increased fundus autofluorescence (FAF) in the perilesional area of geographic atrophy (GA) secondary to age-related macular degeneration. Methods : Serial FAF images of 181 eyes with GA of 134 patients participating in the Directional Spread in Geographic Atrophy study (NCT02051998) were screened for increased FAF spots that had developed during the review period. Thickness and reflectivity of the retinal pigment epithelium (RPE)–basal lamina complex, as well as the integrity of the external limiting membrane (ELM) and the ellipsoid zone (EZ), respectively, in corresponding optical coherence tomography (OCT) scans were compared ...

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    14. Evaluating the impact of optical coherence tomography in diabetic retinopathy screening for an Aboriginal population

      Evaluating the impact of optical coherence tomography in diabetic retinopathy screening for an Aboriginal population

      Importance Optical Coherence Tomography (OCT) is used routinely in management of diabetic eye disease but has not been evaluated in Australian outreach settings for screening programs. Background To evaluate the use of OCT combined with a fundus camera compared to a fundus camera only in a telehealth diabetic retinopathy (DR) screening program for Aboriginal Australians. Design Retrospective comparative study. Participants Patients with diabetes at two Aboriginal Health Services. Methods An intervention group was studied in 2015 using a Topcon 3D OCT-1 Maestro combined OCT/ fundus camera. A control group was studied in 2014 using a DRS non-mydriatic fundus camera. Fundus ...

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    15. Simultaneous refractive index and thickness measurements with a monochromatic low-coherence interferometer

      Simultaneous refractive index and thickness measurements with a monochromatic low-coherence interferometer

      A scanning monochromatic spatial low-coherent interferometer (S-LCI) can be used to simultaneously measure geometric thickness and refractive index. The probe beam of the scanning S-LCI can be an off-axis converging single wavelength laser beam, and the decomposed incident angles of the beam on the sample can be accurately defined in the Fourier domain. The angle dependent phase shift of a plane parallel plate or other sample can be obtained in a single system measurement. From the angle dependent phase shift, the geometric thickness and refractive index of the sample can be simultaneously obtained. Additionally or alternatively, the S-LCI system can ...

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    16. Impacts of implantable collamer lens V4c placement on angle measurements made by optical coherence tomography: two-year follow up

      Impacts of implantable collamer lens V4c placement on angle measurements made by optical coherence tomography: two-year follow up

      Purpose To determine iridocorneal angle changes produced after two years of implantable collamer lens ® (ICL) V4c (STAAR Surgical AG) placement by Fourier-domain optical coherence tomography (FD-OCT). Design Prospective interventional case series. Methods In 54 eyes of 27 myopic subjects FD-OCT (RTVue ® , Optovue Inc.) iridocorneal angle measurements were made before, and 1 month, 3 months, 1 year and 2 years after ICL implant. Trabecular-iris angle (TIA), angle opening distance 500 μm from the scleral spur (AOD 500 ) and iridotrabecular contact length (TICL) were compared among these time points and the quadrants nasal, temporal and inferior. Results Preoperative TIAs were 49.5 ...

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    17. Noninvasive chorioretinal imaging in living rabbits using integrated photoacoustic microscopy and optical coherence tomography

      Noninvasive chorioretinal imaging in living rabbits using integrated photoacoustic microscopy and optical coherence tomography

      Most reported photoacoustic ocular imaging work to date uses small animals, such as mice and rats, the eyeball sizes of which are less than one-third of those of humans, posing challenges for clinical translation. Here we developed a novel integrated photoacoustic microscopy (PAM) and optical coherence tomography (OCT) system for dual-modality chorioretinal imaging of larger animals, such as rabbits. The system has quantified lateral resolutions of 4.1 µm (PAM) and 3.8 µm (OCT), and axial resolutions of 37.0 µm (PAM) and 4.0 µm (OCT) at the focal plane of the objective. Experimental results in living rabbits ...

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    18. QUANTITATIVE ANALYSIS OF THE INNER RETINAL LAYER THICKNESSES IN AGE-RELATED MACULAR DEGENERATION USING CORRECTED OPTICAL COHERENCE TOMOGRAPHY SEGMENTATION

      QUANTITATIVE ANALYSIS OF THE INNER RETINAL LAYER THICKNESSES IN AGE-RELATED MACULAR DEGENERATION USING CORRECTED OPTICAL COHERENCE TOMOGRAPHY SEGMENTATION

      Purpose: To characterize inner retinal damage in patients with dry age-related macular degeneration (AMD) using high-resolution spectral domain optical coherence tomography images. Methods: Sixty eyes of 60 patients with AMD were categorized using the Age-Related Eye Disease Study (AREDS) severity scale. Spectral domain optical coherence tomography images of these patients were quantified by manually correcting the segmentation of each retinal layer, including the retinal nerve fiber layer, ganglion cell layer, and inner plexiform layer to ensure accurate delineation of layers. The mean ganglion cell complex thickness values (ganglion cell layer + inner plexiform layer + retinal nerve fiber layer) were compared with ...

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    19. Automatic segmentation of nine retinal layer boundaries in OCT images of non-exudative AMD patients using deep learning and graph search

      Automatic segmentation of nine retinal layer boundaries in OCT images of non-exudative AMD patients using deep learning and graph search

      We present a novel framework combining convolutional neural networks (CNN) and graph search methods (termed as CNN-GS) for the automatic segmentation of nine layer boundaries on retinal optical coherence tomography (OCT) images. CNN-GS first utilizes a CNN to extract features of specific retinal layer boundaries and train a corresponding classifier to delineate a pilot estimate of the eight layers. Next, a graph search method uses the probability maps created from the CNN to find the final boundaries. We validated our proposed method on 60 volumes (2915 B-scans) from 20 human eyes with non-exudative age-related macular degeneration (AMD), which attested to ...

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