1. Articles in category: Ophthalmology

    1-24 of 8951 1 2 3 4 ... 371 372 373 »
    1. Diabetic retinopathy and OCT angiography: clinical findings and future perspectives

      Diabetic retinopathy and OCT angiography: clinical findings and future perspectives

      In diabetic retinopathy (DR), macular involvement can present as either macular edema or ischemia. Fluorescein angiography remains the gold standard in the evaluation of retinal vascular perfusion and diagnosis of macular ischemia. However, it is a costly, time-consuming technique, it requires venipuncture, and reports of anaphylaxis and death related to fluorescein injections have been documented, despite their rarity. Optical coherence tomography (OCT) provides a fast and non-invasive method to assess retinal structures at a microscopic level. OCT angiography permits the noninvasive study of retinal and choroid circulation via motion contrast imaging. Split-spectrum amplitude decorrelation angiography combined with OCT angiography has ...

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    2. Image analysis in optical coherence tomography Retinal layer segmentation (Thesis)

      Image analysis in optical coherence tomography Retinal layer segmentation (Thesis)

      How do we explain the world around us? Two wise men started the search for an answer thousands of years ago and became two of the most influential philosophers. Their debate still remains with us today. Plato believed true knowledge comes from the mind, which is rational, and not from the senses, which can be fooled. In contrast, Aristotle believed the senses allow us to learn and interact with the world around us. Despite this ongoing debate, we use our senses to experience the world around us. Of all our senses, the sense of sight contributes the most to our ...

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    3. Improving graph-based OCT segmentation for severe pathology in retinitis pigmentosa patients

      Improving graph-based OCT segmentation for severe pathology in retinitis pigmentosa patients

      Three dimensional segmentation of macular optical coherence tomography (OCT) data of subjects with retinitis pigmentosa (RP) is a challenging problem due to the disappearance of the photoreceptor layers, which causes algorithms developed for segmentation of healthy data to perform poorly on RP patients. In this work, we present enhancements to a previously developed graph-based OCT segmentation pipeline to enable processing of RP data. The algorithm segments eight retinal layers in RP data by relaxing constraints on the thickness and smoothness of each layer learned from healthy data. Following from prior work, a random forest classifier is first trained on the ...

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    4. An automated image processing method for classification of diabetic retinopathy stages from conjunctival microvasculature images

      An automated image processing method for classification of diabetic retinopathy stages from conjunctival microvasculature images

      The conjunctiva is a densely vascularized tissue of the eye that provides an opportunity for imaging of human microcirculation. In the current study, automated fine structure analysis of conjunctival microvasculature images was performed to discriminate stages of diabetic retinopathy (DR). The study population consisted of one group of nondiabetic control subjects (NC) and 3 groups of diabetic subjects, with no clinical DR (NDR), non-proliferative DR (NPDR), or proliferative DR (PDR). Ordinary least square regression and Fisher linear discriminant analyses were performed to automatically discriminate images between group pairs of subjects. Human observers who were masked to the grouping of subjects ...

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      Mentions: Mahnaz Shahidi
    5. Collaborative SDOCT segmentation and analysis software

      Collaborative SDOCT segmentation and analysis software

      Spectral domain optical coherence tomography (SDOCT) is routinely used in the management and diagnosis of a variety of ocular diseases. This imaging modality also finds widespread use in research, where quantitative measurements obtained from the images are used to track disease progression. In recent years, the number of available scanners and imaging protocols grown and there is a distinct absence of a unified tool that is capable of visualizing, segmenting, and analyzing the data. This is especially noteworthy in longitudinal studies, where data from older scanners and/or protocols may need to be analyzed. Here, we present a graphical user ...

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    6. Longitudinal analysis of mouse SDOCT volumes

      Longitudinal analysis of mouse SDOCT volumes

      Spectral-domain optical coherence tomography (SDOCT), in addition to its routine clinical use in the diagnosis of ocular diseases, has begun to fund increasing use in animal studies. Animal models are frequently used to study disease mechanisms as well as to test drug efficacy. In particular, SDOCT provides the ability to study animals longitudinally and non-invasively over long periods of time. However, the lack of anatomical landmarks makes the longitudinal scan acquisition prone to inconsistencies in orientation. Here, we propose a method for the automated registration of mouse SDOCT volumes. The method begins by accurately segmenting the blood vessels and the ...

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    7. Extraction of membrane structure in eyeball from MR volumes

      Extraction of membrane structure in eyeball from MR volumes

      This paper presents an accurate extraction method of spherical shaped membrane structures in the eyeball from MR volumes. In ophthalmic surgery, operation field is limited to a small region. Patient specific surgical simulation is useful to reduce complications. Understanding of tissue structure in the eyeball of a patient is required to achieve patient specific surgical simulations. Previous extraction methods of tissue structure in the eyeball use optical coherence tomography (OCT) images. Although OCT images have high resolution, imaging regions are limited to very small. Global structure extraction of the eyeball is difficult from OCT images. We propose an extraction method ...

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    8. Inter-session repeatability of retinal layer thickness in optical coherence tomography

      Inter-session repeatability of retinal layer thickness in optical coherence tomography

      Reliable retinal layer thickness measurements using optical coherence tomography (OCT) are important to track the subtle retinal changes in longitudinal studies. A total of 10 eyes (5 healthy subjects, 40±13 years old) were enrolled to study the inter-session repeatability and identify the pitfalls affecting the reliabilities. Each eye was scanned using spectral domain OCT (Spectralis SDOCT, Heidelberg Engineering) for 3 sessions with 30 seconds rest in between. The first and second sessions were scanned independently and the third one was scanned with the first one as the baseline visit. Each session consisted of a confocal scanning laser ophthalmoscopy (cSLO ...

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    9. Fluorescein Angiography Versus Optical Coherence Tomography Angiography in Macular Telangiectasia Type I Treated With Bevacizumab Therapy

      Fluorescein Angiography Versus Optical Coherence Tomography Angiography in Macular Telangiectasia Type I Treated With Bevacizumab Therapy

      This is a report of microvascular changes seen on fluorescein angiography (FA) and optical coherence tomography angiography (OCTA) in a 47-year-old man with macular telangiectasia Type 1 (MacTel1) after a 7-year bevacizumab (Avastin; Genentech, South San Francisco, CA) treatment course. OCTA allowed for clear visualization of most telangiectasias and aneurysms in the deep capillary plexus, with only few microvascular dilatations in the superficial plexus. In addition, areas of capillary dropout in the superficial and deep vascular plexa located near telangiectasias were documented on OCTA. Serial FA demonstrated reduced number of aneurysms and telangiectasias at the 7-year mark compared to baseline.

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    10. Spectral domain optical coherence tomography features of traumatic macular retinoschisis

      Spectral domain optical coherence tomography features of traumatic macular retinoschisis

      A 30-year-old man noticed acute visual loss in his left eye following explosion of a vehicle tire tube while inflating. On presentation, Snellen visual acuity (VA) was 20/20 in the right eye and 2 meters counting fingers in the left eye. Relative afferent pupillary defect was negative. A small area of temporal conjunctival hemorrhage, anterior chamber red blood cells (1+), and inferotemporal iridodialysis extending 3 clock hours were evident on slit lamp biomicroscopy. Fundus examination revealed thickening and yellow discoloration of the macula and a mild vitreous hemorrhage [Figure 1] . Figure 1: Infrar

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    11. A computer-aided diagnostic system for detecting diabetic retinopathy in optical coherence tomography images

      A computer-aided diagnostic system for detecting diabetic retinopathy in optical coherence tomography images

      Purpose Detection (diagnosis) of diabetic retinopathy (DR) in optical coherence tomography (OCT) images for patients with type 2 diabetes, but almost clinically normal retina appearances. Methods The proposed computer-aided diagnostic (CAD) system detects the DR in three steps: (a) localizing and segmenting 12 distinct retinal layers on the OCT image; (b) deriving features of the segmented layers, and (c) learning most discriminative features and classifying each subject as normal or diabetic. To localise and segment the retinal layers, signals (intensities) of the OCT image are described with a joint Markov-Gibbs random field (MGRF) model of intensities and shape descriptors. Each ...

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    12. Microscope-Integrated OCT Feasibility and Utility With the EnFocus System in the DISCOVER Study

      Microscope-Integrated OCT Feasibility and Utility With the EnFocus System in the DISCOVER Study

      BACKGROUND AND OBJECTIVE: To evaluate the feasibility and utility of a novel microscope-integrated intraoperative optical coherence tomography (OCT) system. PATIENTS AND METHODS: The DISCOVER study is an investigational device study evaluating microscope-integrated intraoperative OCT systems for ophthalmic surgery. This report focuses on subjects imaged with the EnFocus prototype system (Leica Microsystems/Bioptigen, Morrisville, NC). OCT was performed at surgeon-directed milestones. Surgeons completed a questionnaire after each case to evaluate the impact of OCT on intraoperative management. RESULTS: Fifty eyes underwent imaging with the EnFocus system. Successful imaging was obtained in 46 of 50 eyes (92%). In eight cases (16%), surgical ...

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    13. Subfoveal Choroidal Vascularity in Myopia: Evidence From Spectral-Domain Optical Coherence Tomography

      Subfoveal Choroidal Vascularity in Myopia: Evidence From Spectral-Domain Optical Coherence Tomography

      BACKGROUND AND OBJECTIVE: To evaluate subfoveal choroidal vascularity in eyes with myopia in comparison to age-matched healthy subjects. PATIENTS AND METHODS: Retrospective analysis of single foveal enhanced depth imaging optical coherence tomography (EDI-OCT) scans of 30 eyes with myopia (axial length greater than 25 mm). Subfoveal choroidal vascularity was evaluated by calculating vessel-area-to-stromal-area ratio using a previously validated automated algorithm. RESULTS: The subfoveal stromal area was significantly smaller in myopes (0.95 mm 3 ± 0.22 mm 3 ) compared to controls (1.33 mm 3 ± 0.23 mm 3 ; P < .0001). However, there was no significant difference in vascular area ...

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    14. Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Visual dysfunction and its correlation with retinal changes in patients with Alzheimer's disease

      Aim To evaluate visual dysfunction and its correlation with structural changes in the retina in patients with Alzheimer's disease (AD). Methods Patients with AD (n = 24) and controls (n = 24) underwent evaluation of visual acuity (VA), color vision (using the Farnsworth and L’Anthony desaturated (D) 15 color tests), and contrast sensitivity vision (CSV; using the Pelli-Robson chart and CSV-1000E test) to measure visual dysfunction. Structural measurements of the retinal nerve fiber layer (RNFL) and macular thickness were obtained using spectral domain-optical coherence tomography (SD-OCT). Results CSV at three of the four spatial frequencies was significantly worse in AD ...

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    15. Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Surgical treatment and optical coherence tomographic evaluation for accidental laser-induced full-thickness macular holes

      Purpose To report OCT appearance and surgical outcomes of full-thickness macular holes (MHs) accidentally caused by laser devices. Patients and methods This retrospective case series included 11 eyes of 11 patients with laser-induced MHs treated by pars plana vitrectomy, internal limiting membrane (ILM) peeling, and gas or silicone oil tamponade. Evaluations included a full ophthalmic examination, macular spectral-domain optical coherence tomography (SD-OCT), and fundus photography. Main outcome measures is MH closure and final visual acuity; the secondary outcome was the changes of retinal pigment epithelium and photoreceptor layer evaluated by sequential post-operative SD-OCT images. Results Five patients were accidentally injured ...

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    16. New Insights into the Pathoanatomy of Macular Holes Based on Features of Optical Coherence Tomograph

      New Insights into the Pathoanatomy of Macular Holes Based on Features of Optical Coherence Tomograph

      Various important findings related to the development and progression of idiopathic macular holes (MHs) have been described using optical coherence tomography (OCT) since Gass first described the stages of MH development using biomicroscopy in 1988 and 1995. We believe that a system for classifying and staging MHs should reflect the degree of disease status and its progression and have value not only from a practical point of view (by predicting the chance of closure or visual recovery) but also provides researchers and clinicians with insights into the pathogenesis and disease progression of MH. These data pave the way for the ...

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      Mentions: Hyewon Chung
    17. Optical coherence tomography angiography of the peripapillary retina and optic nerve head in dominant optic atrophy

      Optical coherence tomography angiography of the peripapillary retina and optic nerve head in dominant optic atrophy

      Peripapillar and nerve head vessel density (VD) was measured in 10 patients affected by Dominant optic atrophy (DOA) using optical coherence tomography angiography (OCT-A) and compared to the measurements of 15 age- and gender-matched controls. DOA patients showed VD reduction, mostly in the temporal and inferotemporal peripapillary sectors, according to the preferential involvement of the papillomacular bundle. Despite poor best-corrected visual acuity (BCVA), OCT-A revealed good repeatability. VD correlated with functional (mean deviation of visual field and BCVA) and structural (retinal nerve fiber layer thickness) parameters and could be a non-invasive, quantitative tool for the monitoring of the disease and ...

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    18. Underlying Microstructure of Parapapillary Deep-Layer Capillary Dropout Identified by Optical Coherence Tomography Angiography

      Underlying Microstructure of Parapapillary Deep-Layer Capillary Dropout Identified by Optical Coherence Tomography Angiography

      Purpose : To characterize the microstructure underlying the parapapillary deep-layer microvasculature dropout (MvD) identified by optical coherence tomography (OCT) angiography (OCTA) in eyes with primary open-angle glaucoma (POAG). Methods : Parapapillary MvD was defined as a focal sectoral capillary dropout without any visible microvascular network identified in deep-layer en face images obtained using swept-source OCTA. The peripapillary microstructure was characterized in 188 POAG patients with MvD in the parapapillary deep layer. Twelve radial optic nerve images were obtained using swept-source OCT to examine the peripapillary structure and measure the juxtapapillary choroidal thickness (JPCT). The JPCT was also measured in 72 age-matched POAG ...

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    19. Spectral domain optical coherence tomography findings of patients under treatment for pediatric acute lymphoblastic leukemia

      Spectral domain optical coherence tomography findings of patients under treatment for pediatric acute lymphoblastic leukemia

      Purpose To investigate the use of spectral domain optical coherence tomography (SD-OCT) findings in pediatric acute lymphoblastic leukemia (ALL) patients. Methods Children that were diagnosed with precursor B-cell ALL and classified as belonging to the medium-risk group for relapse were selected for this study. Individuals who were in continuous remission and on maintenance therapy were included in the study group. Cases that had central nervous system involvement were excluded. Age-matched, otherwise healthy children were selected for the control group. Each study participant underwent a comprehensive eye examination and SD-OCT evaluation. Thickness measurements were made within the retinal nerve fiber layer ...

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    20. IDx and IBM Watson Health Forge Alliance for Eye Health

      IDx and IBM Watson Health Forge Alliance for Eye Health

      IBM Watson Health and IDx, LLC today announced a five-year strategic alliance to advance eye health through cognitive computing applications. The alliance aims to help primary care providers, hospitals, health systems, and integrated delivery networks deliver value-based care to patients with diabetic retinopathy and other serious eye conditions such as glaucoma and age-related macular degeneration . The alliance expands IBM Watson Health’s focus on eye health. The alliance leverages more than a decade of IDx’s ophthalmic image analysis work and IBM’s cognitive healthcare offerings and global reach. As part of the alliance, IBM Watson Health has the option ...

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    21. OPTICAL PROPERTIES OF PHOTORECEPTOR AND RETINAL PIGMENT EPITHELIUM CELLS INVESTIGATED WITH ADAPTIVE OPTICS OPTICAL COHERENCE TOMOGRAPHY (Thesis)

      OPTICAL PROPERTIES OF PHOTORECEPTOR AND RETINAL PIGMENT EPITHELIUM CELLS INVESTIGATED WITH ADAPTIVE OPTICS OPTICAL COHERENCE TOMOGRAPHY (Thesis)

      Human vision starts when photoreceptors collect and respond to light. Photoreceptors do not function in isolation though, but share close interdependence with neighboring photoreceptors and underlying retinal pigment epithelium (RPE) cells. These cellular interactions are essential for normal function of the photoreceptor-RPE complex, but methods to assess these in the living human eye are limited. One approach that has gained increased promise is highresolution retinal imaging that has undergone tremendous technological advances over the last two decades to probe the living retina at the cellular level. Pivotal in these advances has been adaptive optics (AO) and optical coherence tomography (OCT ...

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    22. QuaSI: Quantile Sparse Image Prior for Spatio-Temporal Denoising of Retinal OCT Data

      QuaSI: Quantile Sparse Image Prior for Spatio-Temporal Denoising of Retinal OCT Data

      Optical coherence tomography (OCT) enables high-resolution and non-invasive 3D imaging of the human retina but is inherently impaired by speckle noise. This paper introduces a spatio-temporal denoising algorithm for OCT data on a B-scan level using a novel quantile sparse image (QuaSI) prior. To remove speckle noise while preserving image structures of diagnostic relevance, we implement our QuaSI prior via median filter regularization coupled with a Huber data fidelity model in a variational approach. For efficient energy minimization, we develop an alternating direction method of multipliers (ADMM) scheme using a linearization of median filtering. Our spatio-temporal method can handle both ...

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    23. Acute Branch Retinal Artery Occlusion and OCT Angiography Imaging

      Acute Branch Retinal Artery Occlusion and OCT Angiography Imaging

      A 70year old male presented with a 2day history of sudden painless decreased vision in the right eye. Other than presbyopia and senile cataracts, there was no significant past ocular history. His past medical history was significant for a cerebral vascular event of unclear origin several years prior. Evaluation revealed a branch retinal artery occlusion. Optical Coherence Tomography (OCT) angiography was employed as part of the evaluation process. We describe the OCT-angiographic findings in acute branch retinal artery occlusion.

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