1. Articles in category: Ophthalmology

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    1. Tear Meniscus Evaluation Using Optical Coherence Tomography in Dry Eye Patients

      Tear Meniscus Evaluation Using Optical Coherence Tomography in Dry Eye Patients

      Purpose To evaluate the tear meniscus in aqueous tear-deficient dry eye patients using Fourier-domain optical coherence tomography (FD-OCT) and to investigate the clinical usefulness of tear meniscus values. Methods The present study included 79 aqueous tear-deficient dry eyes and 50 normal eyes. Tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus area (TMA) were imaged using FD-OCT and measured with computer calipers. Schirmer's test, tear break-up time, and corneal fluorescein staining were also performed and the correlations between the tests were analyzed. Additionally, the diagnostic power of tear meniscus values was compared using area under the receiver ...

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    2. Automated age-related macular degeneration classification in OCT using unsupervised feature learning

      Automated age-related macular degeneration classification in OCT using unsupervised feature learning

      Age-related Macular Degeneration (AMD) is a common eye disorder with high prevalence in elderly people. The disease mainly affects the central part of the retina, and could ultimately lead to permanent vision loss. Optical Coherence Tomography (OCT) is becoming the standard imaging modality in diagnosis of AMD and the assessment of its progression. However, the evaluation of the obtained volumetric scan is time consuming, expensive and the signs of early AMD are easy to miss. In this paper we propose a classification method to automatically distinguish AMD patients from healthy subjects with high accuracy. The method is based on an ...

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    3. Imaging modal content of cone photoreceptors using adaptive optics optical coherence tomography

      Imaging modal content of cone photoreceptors using adaptive optics optical coherence tomography

      It has been long established that photoreceptors capture light based on the principles of optical waveguiding. Yet after decades of experimental and theoretical investigations considerable uncertainty remains, even for the most basic prediction as to whether photoreceptors support more than a single waveguide mode. To test for modal behavior in human cone photoreceptors, we took advantage of adaptive-optics optical coherence tomography (AO-OCT, λc=785 nm) to noninvasively image in three dimensions the reflectance profiles generated in the inner and outer segments (IS, OS) of cones. Mode content was examined over a range of cone diameters by imaging cones from 0 ...

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    4. Automated segmentation of serous pigment epithelium detachment in SD-OCT images

      Automated segmentation of serous pigment epithelium detachment in SD-OCT images

      Pigment epithelium detachment (PED) is an important clinical manifestation of multiple chorio-retinal disease processes, which can cause the loss of central vision. A 3-D method is proposed to automatically segment serous PED in SD-OCT images. The proposed method consists of five steps: first, a curvature anisotropic diffusion filter is applied to remove speckle noise. Second, the graph search method is applied for abnormal retinal layer segmentation associated with retinal pigment epithelium (RPE) deformation. During this process, Bruch’s membrane, which doesn’t show in the SD-OCT images, is estimated with the convex hull algorithm. Third, the foreground and background seeds ...

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    5. Longitudinal graph-based segmentation of macular OCT using fundus alignment

      Longitudinal graph-based segmentation of macular OCT using fundus alignment

      Segmentation of retinal layers in optical coherence tomography (OCT) has become an important diagnostic tool for a variety of ocular and neurological diseases. Currently all OCT segmentation algorithms analyze data independently, ignoring previous scans, which can lead to spurious measurements due to algorithm variability and failure to identify subtle changes in retinal layers. In this paper, we present a graph-based segmentation framework to provide consistent longitudinal segmentation results. Regularization over time is accomplished by adding weighted edges between corresponding voxels at each visit. We align the scans to a common subject space before connecting the graphs by registering the data ...

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    6. Fast and memory-efficient LOGISMOS graph search for intraretinal layer segmentation of 3D macular OCT scans

      Fast and memory-efficient LOGISMOS graph search for intraretinal layer segmentation of 3D macular OCT scans

      Image segmentation is important for quantitative analysis of medical image data. Recently, our research group has introduced a 3-D graph search method which can simultaneously segment optimal interacting surfaces with respect to the cost function in volumetric images. Although it provides excellent segmentation accuracy, it is computationally demanding (both CPU and memory) to simultaneously segment multiple surfaces from large volumetric images. Therefore, we propose a new, fast, and memory-efficient graph search method for intraretinal layer segmentation of 3-D macular optical coherence tomograpy (OCT) scans. The key idea is to reduce the size of a graph by combining the nodes with ...

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    7. Tchebichef moments based nonlocal-means method for despeckling optical coherence tomography images

      Tchebichef moments based nonlocal-means method for despeckling optical coherence tomography images

      Speckle reduction in optical coherence tomography (OCT) images plays an important role in further image analysis. Although numerous despeckling methods, such as the Kuan’s filter, the Frost’s filter, wavelet based methods, anisotropic diffusion methods, have been proposed for despeckling OCT images, these methods generally tend to provide insufficient speckle suppression or limited detail preservation especially at high speckle corruption because of the insufficient utilization of image information. Different from these denoising methods, the nonlocal means (NLM) method explores nonlocal image self-similarities for image denoising, thereby providing a new method for speckle reduction in OCT images. However, the NLM ...

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    8. Automated detection of Schlemm's canal in spectral-domain optical coherence tomography

      Automated detection of Schlemm's canal in spectral-domain optical coherence tomography

      Recent advances in optical coherence tomography (OCT) technology allow in vivo imaging of the complex network of intra-scleral aqueous veins in the anterior segment of the eye. Pathological changes in this network, draining the aqueous humor from the eye, are considered to play a role in intraocular pressure elevation, which can lead to glaucoma, one of the major causes of blindness in the world. Through acquisition of OCT volume scans of the anterior eye segment, we aim at reconstructing the three dimensional network of aqueous veins in healthy and glaucomatous subjects. A novel algorithm for segmentation of the three-dimensional (3D ...

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    9. Combined use of high-density and volumetric optical coherence tomography for the segmentation of neural canal opening in cases of optic nerve edema

      Combined use of high-density and volumetric optical coherence tomography for the segmentation of neural canal opening in cases of optic nerve edema

      In cases of optic-nerve-head edema, the presence of the swelling reduces the visibility of the underlying neural canal opening (NCO) within spectral-domain optical coherence tomography (SD-OCT) volumes. Consequently, traditional SD-OCT-based NCO segmentation methods often overestimate the size of the NCO. The visibility of the NCO can be improved using high-definition 2D raster scans, but such scans do not provide 3D contextual image information. In this work, we present a semi-automated approach for the segmentation of the NCO in cases of optic disc edema by combining image information from volumetric and high-definition raster SD-OCT image sequences. In particular, for each subject ...

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    10. Automated retinal fovea type distinction in spectral-domain optical coherence tomography of retinal vein occlusion

      Automated retinal fovea type distinction in spectral-domain optical coherence tomography of retinal vein occlusion

      Spectral-domain Optical Coherence Tomography (SD-OCT) is a non-invasive modality for acquiring high- resolution, three-dimensional (3D) cross-sectional volumetric images of the retina and the subretinal layers. SD-OCT also allows the detailed imaging of retinal pathology, aiding clinicians in the diagnosis of sight degrading diseases such as age-related macular degeneration (AMD), glaucoma and retinal vein occlusion (RVO). Disease diagnosis, assessment, and treatment will require a patient to undergo multiple OCT scans, possibly using multiple scanners, to accurately and precisely gauge disease activity, progression and treatment success. However, cross-vendor imaging and patient movement may result in poor scan spatial correlation potentially leading to ...

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    11. Can ganglion cell complex assessment on cirrus HD OCT aid in detection of early glaucoma?

      Can ganglion cell complex assessment on cirrus HD OCT aid in detection of early glaucoma?

      Context Ganglion cell complex is damaged early in glaucoma. Does this loss of GCC help in early diagnosis of glaucoma. Aims To compare the RNFL thickness and ganglion cell complex (GCC) in diagnosed patients of glaucoma, pre-perimetric glaucoma and normal controls. Settings and design Case controlled, observational study. Methods and material 33 glaucoma patients, 45 pre-perimetric glaucoma, and 30 controls were enrolled in the study. ONH parameters on cirrus HD OCT like CD ratio, para papillary RNFL thickness and GCC were calculated for each case. Statistical analysis used ANOVA test to analyse differences between groups. ROC for ganglion cell layer ...

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    12. Comparison of Physiologic versus Pharmacologic Mydriasis on Anterior Chamber Angle Measurements Using Spectral Domain Optical Coherence Tomography

      Comparison of Physiologic versus Pharmacologic Mydriasis on Anterior Chamber Angle Measurements Using Spectral Domain Optical Coherence Tomography

      Purpose. To compare the effects of physiologic versus pharmacologic pupil dilation on anterior chamber angle (ACA) measurements obtained with spectral domain optical coherence tomography (SD-OCT). Methods. Forty eyes from 20 healthy, phakic individuals with open angles underwent anterior segment OCT imaging under 3 pupillary states: (1) pupil constricted under standard room lighting, (2) physiologic mydriasis in a darkened room, and (3) postpharmacologic mydriasis. Inferior angle Schwalbe’s line-angle opening distance (SL-AOD) and SL-trabecular-iris-space area (SL-TISA) were computed for each eye and pupillary condition by masked, certified Reading Center graders using customized grading software. Results. SL-AOD and SL-TISA under pupillary constriction ...

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    13. Pars Plana Vitrectomy with Air Tamponade for Optic Disc Pit Maculopathy: Swept-source Optical Coherence Tomography Imaging Findings and Surgical Approach

      Pars Plana Vitrectomy with Air Tamponade for Optic Disc Pit Maculopathy: Swept-source Optical Coherence Tomography Imaging Findings and Surgical Approach

      Purpose: To describe how Swept Source Optical Coherence Tomography (SS-OCT) provides enhanced diagnostic information enabling optimisation of surgical strategy in a pediatric patient suffering from ODP maculopathy. We report the first case of successful management of ODP maculopathy via pars plana vitrectomy (PPV) and air tamponade. Methods: Interventional case report. Results: A five-year-old girl presented with ODP and serous macular detachment in her previously amblyopic left eye. SS-OCT showed optically opaque vitreous fibres perpendicularly attached to the base of the optic nerve head excavation and what appeared to be fibrous tissue at the base of the excavation of the optic ...

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    14. Applicability of the ISNT and IST rules on retinal nerve fiber layer measurement on spectral-domain optical coherence tomography in normal Indian children

      Applicability of the ISNT and IST rules on retinal nerve fiber layer measurement on spectral-domain optical coherence tomography in normal Indian children

      Background To determine the applicability of the ISNT (inferior>superior>nasal>temporal) and IST (inferior>superior>temporal) rules on retinal nerve fiber layer (RNFL) measurement on spectral-domain optical coherence tomography (SD-OCT) in normal children. Methods A prospective, cross-sectional study including consecutive subjects between the ages of 5–18 years who were born at term (≥37 weeks gestational age) and with a normal birth weight (≥2500 g) presenting to the out-patient department for refractive error examination. RNFL measurement was done on Spectralis SD-OCT. Exclusion criteria were best-corrected visual acuity less than 20/20, spherical equivalent (SE) > ± 5 diopter (D), applanation IOP ...

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    15. Corneal Stromal Demarcation Line Determined With Anterior Segment Optical Coherence Tomography Following a Very High Intensity Corneal Collagen Cross-Linking Protocol

      Corneal Stromal Demarcation Line Determined With Anterior Segment Optical Coherence Tomography Following a Very High Intensity Corneal Collagen Cross-Linking Protocol

      Purpose: To evaluate corneal stromal demarcation line depth after very high intensity (18 mW/cm2) ultraviolet-A irradiation for a 5-minute corneal collagen cross-linking (CXL) protocol with the use of anterior segment optical coherence tomography. Methods: This prospective interventional study enrolled 14 patients (18 eyes) with progressive keratoconus who underwent CXL with an ultraviolet-A irradiation intensity of 18 mW/cm2 for 5 minutes. One month postoperatively, corneal stromal demarcation line depth was measured with the use of anterior segment optical coherence tomography by 2 independent observers. The rate of reepithelialization and endothelial cell density at a 3-month follow-up period were also ...

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    16. Anomalous optical coherence tomography findings in Wyburn-Mason syndrome and isolated retinal arteriovenous malformation

      Anomalous optical coherence tomography findings in Wyburn-Mason syndrome and isolated retinal arteriovenous malformation

      We report 2 cases of unilateral retinal arteriovenous malformation (AVM) with previously unreported anomalies of the inner retinal layers detected on spectral domain optical coherence tomography (SD-OCT): a 5-year-old girl with a large unilateral retinal AVM, ipsilateral visual acuity of 20/200, and ipsilateral intracranial AVM; and a 10-year-old boy with a large unilateral retinal AVM, ipsilateral visual acuity of 20/20, ipsilateral temporal visual field defects, and no intracranial AVM. Both macular SD-OCT findings showed multiple large inner retinal vessels that created a prominent shadowing artifact, retinal thickening, and speckling and heterogeneity of inner retinal layers.

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    17. Multimodal Imaging In Type 2 Idiopathic Macular Telangiectasia

      Multimodal Imaging In Type 2 Idiopathic Macular Telangiectasia

      Background: Macular telangiectasia Type 2 is a bilateral, progressive potentially blinding retinal disease characterized by both vascular and neurodegenerative signs that have been documented using different imaging techniques. The correlation between macular telangiectasia Type 2 signs from various imaging modalities is unknown. Our aim was to investigate the relationship of various macular telangiectasia Type 2 signs using fundus fluorescein angiography, optical coherence tomography and dual-wavelength autofluorescence images. Methods: Participants were selected from the macular telangiectasia Type 2 Natural History Observation Study, based on a confirmed diagnosis and the availability of images. Signs in fundus fluorescein angiography, dual-wavelength autofluorescence, and optical ...

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    18. Preoperative OCTs for multifocal patients

      Preoperative OCTs for multifocal patients

      W hen implanting a multifocal IOL (MFIOL), it is vital the patient be a good candidate, so a careful preoperative examination is necessary. This may include optical coherence tomography (OCT) to check for any macular pathology or retina problems. Carl Regillo, MD, Mid Atlantic Retina, Philadelphia; Jeffrey Heier, MD, Ophthalmic Consultants of Boston; and Pravin Dugel, MD, Retinal Consultants of Arizona, Phoenix, spoke about important things to know about a preop examination.

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      Mentions: Optos
    19. Detecting corneal bulging with swept-source OCT

      Detecting corneal bulging with swept-source OCT

      C orneal ectasia after LASIK ranks in seriousness to endophthalmitis after cataract surgery. While the severity of each problem differs, these continue to be a significant issue when they occur after their relative surgeries. Ectasia continues to mystify, to some extent. Forme fruste keratoconus, numerous LASIK procedures, and even high myopia are just some of the risk factors for the disease, but nothing predicts with 100% accuracy who will get ectasia. Refractive surgery itself has been known to potentially cause forward protrusion of the posterior cornea, suggesting that minor bulging of the eye happens in some cases. Given the wide ...

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    20. Correlation between depth and area of retinal nerve fiber layer defect as measured by spectral domain optical coherence tomography

      Correlation between depth and area of retinal nerve fiber layer defect as measured by spectral domain optical coherence tomography

      Background To evaluate the correlation between the depth and area of retinal nerve fiber layer (RNFL) defect, as measured on an RNFL map of spectral-domain optical coherence tomography (SD-OCT). Methods The RNFL of 472 glaucoma subjects and of 217 healthy subjects was imaged by an SD-OCT. RNFL defect depth and area on the RNFL map were expressed as an RNFL defect depth percentage index (RDPI) and an RNFL defect area index (RDAI), respectively, according to the following two formulas: 100×[1–{summation of thicknesses of RNFL defects/summation of thicknesses of upper 95th percentile range of age-matched healthy subjects in ...

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    21. Anterior and Posterior Ocular Biometry in Healthy Chinese Subjects: Data Based on AS-OCT and SS-OCT

      Anterior and Posterior Ocular Biometry in Healthy Chinese Subjects: Data Based on AS-OCT and SS-OCT

      Background To measure the anterior and posterior ocular biometric characteristics concurrently and to determine the relationship between the iris and choroid in healthy Chinese subjects. Methods A total of 148 subjects (270 eyes) were enrolled in this cross-section study. The anterior and posterior ocular biometric characteristics were measured simultaneously by anterior segment optical coherence tomography (AS-OCT) and swept-source optical coherence tomography (SS-OCT). Results Compared with male eyes, female eyes had narrower anterior biometric parameters that presented with smaller anterior segment parameters [including anterior chamber depth (ACD), width (ACW), area (ACA), and volume (ACV); (all p<0.001)], narrower anterior chamber ...

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    22. Optical Coherence Tomography Opens a New Era in the Afferent Visual System Evaluation

      Optical Coherence Tomography Opens a New Era in the Afferent Visual System Evaluation

      For decades, thinning of the retinal nerve fiber layer in optic neuropathy could only be observed ophthalmoscopically or using red-free fundus photography. These days are over. Subsequently, different techniques to image the optic nerve and the retina have been developed. Optical coherence tomography (OCT) has gained the most attention and has opened a new area of revolutionary diagnostic possibilities. OCT is a noncontact diagnostic imaging technique that provides detailed, cross-sectional images of the retina and the optic disc in vivo. It was first used in 1991 to visualize the eye.[ 1 ] Image capture is noninvasive, painless, and fast. The technology ...

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    23. Applications of Optical Coherence Tomography in Pediatric Clinical Neuroscience

      Applications of Optical Coherence Tomography in Pediatric Clinical Neuroscience

      For nearly two centuries, the ophthalmoscope has permitted examination of the retina and optic nerve—the only axons directly visualized by the physician. The retinal ganglion cells project their axons, which travel along the innermost retina to form the optic nerve, marking the beginning of the anterior visual pathway. Both the structure and function of the visual pathway are essential components of the neurologic examination as it can be involved in numerous acquired, congenital and genetic central nervous system conditions. The development of optical coherence tomography now permits the pediatric neuroscientist to visualize and quantify the optic nerve and retinal ...

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    24. Spectral-Domain Optical Coherence Tomography Angiography of Choroidal Neovascularization

      Spectral-Domain Optical Coherence Tomography Angiography of Choroidal Neovascularization

      Purpose To describe the characteristics as well as the sensitivity and specificity of detection of choroidal neovascularization (CNV) on optical coherence tomography angiography (OCTA) using spectral-domain optical coherence tomography. Design Observational, retrospective study. Participants Seventy-two eyes of 61 subjects (48 eyes of 43 subjects with CNV, 24 eyes of 18 subjects without CNV). Methods Patients imaged using the prototype AngioVue OCTA system (Optovue, Inc, Fremont, CA) between August 2014 and October 2014 at New England Eye Center were assessed. Patients in whom CNV was identified on OCTA were evaluated to define characteristics of CNV on OCTA: size using greatest linear ...

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