1. Articles in category: Ophthalmology

    49-72 of 14095 « 1 2 3 4 5 6 ... 586 587 588 »
    1. Quantification of retinal microvascular density using optic coherence tomography angiography in primary angle closure disease

      Quantification of retinal microvascular density using optic coherence tomography angiography in primary angle closure disease

      Purpose : To evaluate the microvascular density of the peripapillary and parafoveal areas of the eyes with primary angle closure disease (PACD) using optical coherence tomography angiography (OCTA). Materials and methods : An observational study was conducted with 76 PACD patients (29 eyes with primary angle closure suspect, 22 eyes with primary angle closure [PAC], and 25 eyes with primary angle closure glaucoma [PACG]) and 27 control eyes. OCTA was performed for all subjects to acquire a 4.5 × 4.5 mm scanning area centered on the optic discs and a 3 × 3 mm parafoveal cubes. Peripapillary and parafoveal vessel density (VD ...

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    2. Imaging of a retinal pigment epithelium aperture using polarization-sensitive optical coherence tomography

      Imaging of a retinal pigment epithelium aperture using polarization-sensitive optical coherence tomography

      Purpose: To evaluate cases with a retinal pigment epithelium (RPE) aperture using polarization-sensitive optical coherence tomography (PS-OCT). Study design: Retrospective consecutive case series. Methods: A retrospective study that included three eyes (three patients) with RPE aperture and age-related macular degeneration (AMD) evaluated at the Macular Clinic in Tokyo University Hospital. A three-dimensional dataset of depolarization information was obtained with a clinical prototype of PS-OCT. Results: All patients were categorized as intermediate AMD. RPE apertures were identified with PS-OCT as discontinuities of depolarization in the RPE layer of the pigment epithelial detachment (PED). A nonuniform decrease of depolarization in the RPE ...

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    3. Investigation of macular and optic nerve head structural changes using spectral domain optical coherence tomography in internal carotid artery stenosis

      Investigation of macular and optic nerve head structural changes using spectral domain optical coherence tomography in internal carotid artery stenosis

      Purpose To demonstrate differences in optic nerve head (ONH), retinal nerve fiber layer (RNFL), and macular thickness in patients with internal carotid artery (ICA) stenosis using spectral domain optical coherence tomography (SD-OCT). Methods A case-controlled study was conducted in 31 patients with a diagnosis of unilateral ICA stenosis (the percentage of stenosis was between 65 and 85%), and 53 age- and sex-matched healthy subjects (control group) from March 2016 to April 2018. The ONH parameters, RNFL, and macular thicknesses in the nine macular quadrants according to the Early Treatment Diabetic Retinopathy Study (ETDRS) were measured using SD-OCT. Results The average ...

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    4. Effects of age and binarising area on choroidal vascularity index in healthy eyes: an optical coherence tomography study

      Effects of age and binarising area on choroidal vascularity index in healthy eyes: an optical coherence tomography study

      Purpose: To investigate the changes in the choroidal vascularity index (CVI) with age and to compare the effect of the binarised area on CVI in healthy eyes using spectral-domain optical coherence tomography (SD-OCT). Materials and methods: Two hundred and twenty-four eyes of 224 healthy subjects were included in this prospective cross-sectional study. The eyes were divided into different age groups to analyse the possible age-related choroidal structural changes. Subfoveal choroidal thickness (SFCT), CVI, total choroidal area (TCA), stromal area (SA), luminal area (LA), and CVI within the central 1500 µm of the macula were analysed using enhanced depth imaging SD-OCT ...

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    5. A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps

      A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps

      PURPOSE: To develop a coincident thinning (CTN) index to differentiate between keratoconic and healthy corneas using optical coherence tomography (OCT) measurements of pachymetry and epithelial thickness. METHODS: Pattern deviation maps of pachymetry and epithelial thickness were generated using Fourier-domain OCT images of the cornea. The co-localized thinning of the two maps was quantified using a novel CTN index, which was calculated from Gaussian fits of the regions of maximum relative thinning. The CTN index was validated using k-fold cross-validation, and its classification performance was compared to minimum pachymetry and maximum keratometry. RESULTS: A total of 82 normal eyes and 133 ...

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    6. Comparison of two different optical coherence tomography angiography devices in detecting healthy versus glaucomatous eyes - an observational cross-sectional study

      Comparison of two different optical coherence tomography angiography devices in detecting healthy versus glaucomatous eyes - an observational cross-sectional study

      Background: To understand the differences between two different optical coherence tomography angiography (OCTA) devices in detecting glaucomatous from healthy eyes by comparing their vascular parameters, diagnostic accuracy and test-retest reliability. Methods: A cross-sectional observational study was performed on healthy and glaucoma subjects, on whom two sets of OCTA images of optic disc and macula were acquired using both AngioVue (Optovue, USA) and Swept Source (Topcon, Japan) OCTA devices during one visit. A novel in-house software was used to calculate the vessel densities. Diagnostic accuracy of the machines in differentiating healthy versus glaucomatous eyes was determined using area under the receiver ...

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    7. Study of Retinal Nerve Fiber Layer Thickness by Optical Coherence Tomography in Primary Open Angle Glaucoma, Glaucoma Suspect and Normal Nepalese Population

      Study of Retinal Nerve Fiber Layer Thickness by Optical Coherence Tomography in Primary Open Angle Glaucoma, Glaucoma Suspect and Normal Nepalese Population

      The measurement of retinal nerve fiber layer thickness can help significantly in the early diagnosis of glaucoma and monitoring of its progression. The objective of this study was to compare the retinal nerve fiber layer (RNFL) thickness by optical coherence tomography in primary open angle glaucoma, glaucoma suspects and normal Nepalese population. This was a hospital based cross-sectional study conducted in the Ophthalmology Out Patient Department of Manipal Teaching Hospital, Pokhara. Total 100 numbers of subjects (40 primary open angle glaucoma, 30 glaucoma suspects and 30 normal people) were evaluated. Complete ophthalmological examinations including tonometry, gonioscopy, optical coherence tomography, perimetry ...

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    8. Quantitative multi-contrast in vivo mouse imaging with polarization diversity optical coherence tomography and angiography

      Quantitative multi-contrast in vivo mouse imaging with polarization diversity optical coherence tomography and angiography

      Retinal microvasculature and the retinal pigment epithelium (RPE) play vital roles in maintaining the health and metabolic activity of the eye. Visualization of these retina structures is essential for pre-clinical studies of vision-robbing diseases, such as age-related macular degeneration (AMD). We have developed a quantitative multi-contrast polarization diversity OCT and angiography (QMC-PD-OCTA) system for imaging and visualizing pigment in the RPE using degree of polarization uniformity (DOPU), along with flow in the retinal capillaries using OCT angiography (OCTA). An adaptive DOPU averaging kernel was developed to increase quantifiable values from visual data, and QMC en face images permit simultaneous visualization ...

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    9. Generating large field of view en-face projection images from intra-acquisition motion compensated volumetric optical coherence tomography data

      Generating large field of view en-face projection images from intra-acquisition motion compensated volumetric optical coherence tomography data

      A technique to generate large field of view projection maps of arbitrary optical coherence tomography (OCT) data is described. The technique is divided into two stages - an image acquisition stage that features a simple to use fast and robust retinal tracker to get motion free retinal OCT volume scans - and a stitching stage where OCT data from different retinal locations is first registered against a reference image using a custom pyramid-based approach and finally stitched together into one seamless large field of view (FOV) image. The method is applied to data recorded with a polarization sensitive OCT instrument in healthy ...

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    10. Swept Source Optical Coherence Tomography Assessment of Bursa Premacularis in Healthy Eyes

      Swept Source Optical Coherence Tomography Assessment of Bursa Premacularis in Healthy Eyes

      Purpose . To describe the reliability and the limits of bursa premacularis (BPM) evaluation using a swept source optical coherence tomography (SS-OCT) device with enface and 16 mm-high definition (HD) longitudinal scans. Methods . 60 eyes of 60 subjects were enrolled and imaged with SS-OCT system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). BPM area was measured using enface scans imported to ImageJ. HD horizontal and vertical longitudinal scans centered at the fovea were used to detect width (W) and central thickness (CT) of BPM at baseline (T 0 ) and after 30 minutes (T 30 ) performed by two different ...

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    11. Foveal avascular zone analysis by optical coherence tomography angiography in patients with type 1 and 2 diabetes and without clinical signs of diabetic retinopathy

      Foveal avascular zone analysis by optical coherence tomography angiography in patients with type 1 and 2 diabetes and without clinical signs of diabetic retinopathy

      Purpose To analyze the early macular microvascular alterations in patients with type 1 and 2 diabetes mellitus (DM) without diabetic retinopathy (DR), using optical coherence tomography angiography (OCT-A), and compare these with nondiabetic patients. Methods This prospective study involved 93 patients with type 1 diabetes (DM1), 104 patients with type 2 diabetes (DM2) without signs of DR, and 71 healthy subjects for the control group. The foveal avascular zone (FAZ) area and the vessel density (VD) at the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were evaluated. Results The SCP and DCP FAZ areas were significantly larger in ...

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    12. Ocular imaging at the cutting-edge

      Ocular imaging at the cutting-edge

      Barely three decades ago, ophthalmic images were mostly limited to film-based slit-lamp photography, fundus photography, fluorescein angiography (FA) and B-scan ultrasounds. With the rapid development in digital imaging technology and computer processing power, multiple innovative ocular imaging investigations have become available and are now essential parts of our daily clinical practice. In this special issue of Eye , experts from around the world summarised the recent major advancements in ocular imaging and their impacts in various fields of ophthalmology. One of the most remarkable development in the field of ocular imaging is the optical coherence tomography (OCT). OCT has greatly enhanced ...

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    13. Multimodal Imaging of Large Optic Disc Coloboma: A Report of Three Cases

      Multimodal Imaging of Large Optic Disc Coloboma: A Report of Three Cases

      Optic disc coloboma (ODC) is a rare congenital anomaly of the optic nerve. Optical coherence tomography (OCT) helps to monitor the complications when there is associated retinoschisis, retinal detachment, or peripapillary neovascularization, while being minimally invasive. OCT angiography could help to better understand this entity from a vascular perspective. We report multimodal imaging of 3 children with large ODC associated with cat eye syndrome, CHARGE syndrome (coloboma, heart defects, atresia choanae, growth retardation, genital abnormalities, and ear abnormalities), and branchio-oculo-facial syndrome.

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    14. Acute Bilateral Uveitis, Hypotony, and Cataracts Associated with Ipilimumab and Nivolumab Therapy: Optical Coherence Tomography Angiography Findings

      Acute Bilateral Uveitis, Hypotony, and Cataracts Associated with Ipilimumab and Nivolumab Therapy: Optical Coherence Tomography Angiography Findings

      Immune checkpoint inhibitors are increasingly being used for the treatment of several malignancies. In rare cases, patients develop disabling ophthalmic side effects such as dry eyes, episcleritis, keratitis, uveitis, inflammatory orbitopathy, myasthenia gravis, macular edema, and serous retinal detachment. We present a case of acute bilateral anterior uveitis, prolonged hypotony, and cataracts following the use of dual therapy ipilimumab and nivolumab.

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    15. AS OCT Evaluation for Perforated Punctual Plugs

      AS OCT Evaluation for Perforated Punctual Plugs

      Prospective non randomized case series study included 50 eyes. The study is conducted on patients attending to the oculoplastic unit of ophthalmology department of Minia university hospital. Informed consents were obtained from the participants in this study. The study was adherent to the tenets of declaration of Heleniski. Anterior segment optical coherence tomography (AS-OCT) was performed for the included patients after perforated plug implantation (during the first operative weak)

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    16. Iris edge detection in Optical Coherence Tomography

      Iris edge detection in Optical Coherence Tomography

      A-lines are obtained from an OCT scan of the eye, some of which pass through the iris and the lens and some of which pass through the lens but not the iris. An interface is detected from the A-lines; at least some of this interface is assumed to correspond to either the anterior or posterior of the iris. For each A-line, a first metric is derived from pixels near the detected first interface, such that the first metric reflects an OCT signal intensity associated with the interface, and a second metric is derived from pixels further from the interface, such ...

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    17. Reconfigurable optical coherence tomography (OCT) system

      Reconfigurable optical coherence tomography (OCT) system

      An optical coherence tomography (OCT) apparatus includes an optical source module comprising two or more selectable optical sources or an optical source configured to selectively operate in two or more source operating modes, or a combination of both, and further comprises an OCT engine coupled to the optical source module, the OCT engine comprising an OCT interferometer. The OCT apparatus still further includes a mode-switching optics module coupled to the OCT engine and comprising one or more swappable, selectable, or adjustable optical components, such that the mode-switching optics module is configured to selectively provide two or more optical configurations for ...

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      Mentions: Alcon
    18. Optical coherence tomography (OCT) imaging surgical target tissue by nonlinear scanning of an eye

      Optical coherence tomography (OCT) imaging surgical target tissue by nonlinear scanning of an eye

      Systems and techniques for laser surgery are described. Scan data may be created by determining a coordinate of the object at a set of points along an arc by the imaging system, wherein the coordinate of the object is a Z coordinate of an object layer. An object shape parameter and position parameter may be determined based on the scan data by a system control module by extracting an amplitude and a phase of the scan data determining a center of the object layer based on the extracted amplitude and phase.

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      Mentions: Alcon
    19. Combination of snapshot hyperspectral retinal imaging and optical coherence tomography to identify Alzheimer’s disease patients

      Combination of snapshot hyperspectral retinal imaging and optical coherence tomography to identify Alzheimer’s disease patients

      The eye offers potential for the diagnosis of Alzheimer’s disease (AD) with retinal imaging techniques being explored to quantify amyloid accumulation and aspects of neurodegeneration. To assess these changes, this proof-of-concept study combined hyperspectral imaging and optical coherence tomography to build a classification model to differentiate between AD patients and controls.

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      Mentions: K. U. Leuven
    20. Bimodal and Coaxial High Resolution Ophthalmic Imaging

      Bimodal and Coaxial High Resolution Ophthalmic Imaging

      The knowledge of the pathogenesis of retinal affections, a major cause of blindness, has greatly benefited from recent advances in retinal imaging. However, optical aberrations of the ocular media limit the resolution that can be achieved by current techniques. The use of an adaptive optics system improves the resolution of ophthalmoscopes by several orders of magnitude, allowing the visualization of many retinal microstructures: photoreceptors, vessels, bundles of nerve fibers. Recently, the development of the coupling of the two main imaging techniques, the Adaptive Optics Ophthalmoscope with Optical Coherence Tomography , enables unparalleled three-dimensional in vivo cell-scale imaging, while remaining comfortable for ...

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    21. Optical coherence tomography angiography characteristics of choroidal melanoma

      Optical coherence tomography angiography characteristics of choroidal melanoma

      Purpose The purpose of this study is to evaluate tumour vasculature with optical coherence tomography angiography (OCTA) in malignant choroidal melanoma (CM). Materials and methods Patients with unilateral CM were included in this cross-sectional observational clinical study. Applying OCTA systems operating at 840-nm wavelengths, eyes with CM were imaged. The primary main outcome measures were OCTA images, qualitative evaluation of macular and tumour vasculature, quantitative vascular density (VD), perfusion density (PD) and the foveal avascular zone disruption. Results The study included 11 patients with unilateral CM and contralateral unaffected eyes as the control group. Eyes of 11 patients with CM ...

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    22. Optical coherence tomography in the 2020s—outside the eye clinic

      Optical coherence tomography in the 2020s—outside the eye clinic

      Optical coherence tomography (OCT) is a paragon of success in the translation of biophotonics science to clinical practice. OCT systems have become ubiquitous in eye clinics but access beyond this is limited by their cost, size and the skill required to operate the devices. Remarkable progress has been made in the development of OCT technology to improve the speed of acquisition, the quality of images and into functional extensions of OCT such as OCT angiography. However, more needs to be done to radically improve the access to OCT by addressing its limitations and enable penetration outside of typical clinical settings ...

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    23. Optical Coherence Tomography: from Technology to Applications in Ophthalmology

      Optical Coherence Tomography: from Technology to Applications in Ophthalmology

      The relatively fast translation of optical coherence tomography (OCT) from an optical measurement technology to a standard of care in ophthalmology was driven by its ability to address clear unmet diagnostic needs. OCT's further technological developments have expanded its clinical use by extending the imaging range (wider, deeper) and the imaging contrast (from morphology to blood flow). The translation of technical advances into clinical value is an ongoing process involving both the potential substitution of established diagnostics (such as fundus angiography) and the identification of novel feature‐disease correlations. This review looks into the development, the status and the ...

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    24. Differential Diagnosis of Ischemic Vertigo by Optical Coherence Tomography

      Differential Diagnosis of Ischemic Vertigo by Optical Coherence Tomography

      Objective : This study aimed to evaluate the differences in the mean retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) in patients with early stage central vertigo with or without vertebrobasilar stenosis detected by Doppler ultrasound. Materials and Methods : A total of 50 patients with ischemic vertigo and 50 healthy individuals were included in the study. The distinction between central and peripheral vertigo was determined by physical and neurological examinations and the Dix-Hallpike maneuver. For all patients, the mean RNFL thickness was determined using OCT performed by 2 independent ophthalmologists. Results : There were no significant differences between the ...

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