1. Articles in category: Ophthalmology

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    1. An Overview of OCT Techniques for Detection of Ophthalmic Syndromes

      An Overview of OCT Techniques for Detection of Ophthalmic Syndromes

      The retina is an essential part of the human eye. It is a very small part at the subsequent pole of the human eye, and it is composed of a tissue cell that can detect the presence of light. The tissue is sensitive enough to detect the amount of light present, its intensity, and a range of different wavelengths as well. These tissues generate nerve signals, and those signals are passed to the brain via the optic nerve. If the retina malfunctions, then different retinal disorders can occur such as diabetic retinopathy, glaucoma, and pathologic myopia. These can be considered ...

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    2. En Face Optical Coherence Tomography Imaging of the Photoreceptor Layers in Hydroxychloroquine Retinopathy

      En Face Optical Coherence Tomography Imaging of the Photoreceptor Layers in Hydroxychloroquine Retinopathy

      Objective To investigate the application of en face optical coherence tomography (OCT) imaging in eyes with hydroxychloroquine (HCQ) retinopathy. Design Retrospective case series Methods: Setting Institutional Patient Population Sixty-two eyes of 31 Asian patients with HCQ retinopathy. Observation Procedures Macular volume scanning using swept-source OCT was performed in 6 × 6 and 9 × 9 mm areas centered on the fovea. Segmentation of the photoreceptor layers was automatically performed between the inner border of the ellipsoid zone and that of the retinal pigment epithelium-Bruch’s membrane complex to obtain en face OCT images. Findings from the en face images were qualitatively and ...

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    3. A vision exam focused on preemies

      A vision exam focused on preemies

      Many babies born prematurely grow up to be healthy, happy kids. But those who weigh below 2 ¾ pounds at birth could have problems seeing well. This is something Michelle T. Cabrera, an associate professor of ophthalmology at the University of Washington School of Medicine and a pediatric ophthalmologist at Seattle Childrens, wants to help fix. She is using handheld, swept source optical coherence tomography in a study of 50 premature infants. The device obtains high-resolution, cross-sectional images of the vitreous in the babies’ eyes. The vitreous is the eye’s gel-like filling. The pictures Cabrera is taking can show fine ...

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    4. Ocular coherence tomography‐measured changes over time in anterior chamber angle and diurnal intraocular pressure after laser iridotomy: IMPACT study

      Ocular coherence tomography‐measured changes over time in anterior chamber angle and diurnal intraocular pressure after laser iridotomy: IMPACT study

      Importance The change in the anatomical dimensions over time and the effect on diurnal intraocular pressure (DIOP) following laser peripheral iridotomy is poorly understood. Background To evaluate change over time in anterior chamber angle anatomy following laser peripheral iridotomy (LPI) in patients with primary angle closure compared to control eyes. Additionally, the effect of LPI on DIOP fluctuation was investigated. Design Longitudinal, prospective, double‐randomized research study. Participants Adults with suspected angle closure or angle closure diagnosis referred to hospital services in the United Kingdom. Methods Thirty‐nine patients newly diagnosed with bilateral primary angle closure/suspects (PAC/PACS) received ...

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    5. Feature-oriented singular value shrinkage for optical coherence tomography image

      Feature-oriented singular value shrinkage for optical coherence tomography image

      Optical coherence tomography (OCT) is a non-invasive optical imaging modality that has been widely used in the field of medical diagnosis. However, OCT images are often degraded by speckle noise. To address this problem, this paper proposes a two-stage feature-oriented singular value shrinkage algorithm in a low-rank approximation framework, for speckle noise reduction and contrast enhancement of intra-retinal layers of OCT images. First, a weighted absolute distance is employed to find nonlocal similar patches that exhibit high correlation to a given reference one. Next, the singular values of the group matrix formed by similar patches are shrunk by mixed thresholding ...

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    6. The Validity of Optical Coherence Tomography Angiography as a Screening Test for the Early Detection of Retinal Changes in Patients with Hydroxychloroquine Therapy

      The Validity of Optical Coherence Tomography Angiography as a Screening Test for the Early Detection of Retinal Changes in Patients with Hydroxychloroquine Therapy

      Purpose : The aim of this study was to quantitatively compare both the vessel density of macular capillary plexuses and the foveal avascular zone (FAZ) areas of patients receiving hydroxychloroquine (HCQ) therapy for more than 5 years while using age- and sex- matched controls. Methods : The patients undergoing HCQ who were screened for toxic effects were evaluated. The FAZ parameters included the area, perimeter, and the acircularity index. The foveal density and vessel density values of both the superficial (SCP) and deep capillary plexuses (DCP) were measured using optical coherence tomography angiography (OCTA). Results : This study included 80 eyes of 40 ...

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    7. Ultrahigh Resolution Mouse Optical Coherence Tomography to Aid Intraocular Injection in Retinal Gene Therapy Research

      Ultrahigh Resolution Mouse Optical Coherence Tomography to Aid Intraocular Injection in Retinal Gene Therapy Research

      HR-SD-OCT is utilized to monitor the progression of photoreceptor degeneration in live mouse models, assess the delivery of therapeutic agents into the subretinal space, and to evaluate toxicity and efficacy in vivo. HR-SD-OCT uses near infrared light (800-880 nm) and has optics specifically designed for the unique optics of the mouse eye with sub-2-micron axial resolution. Transgenic mouse models of outer retinal (photoreceptor) degeneration and controls were imaged to assess the disease progression. Pulled glass microneedles were used to deliver sub retinal injections of adeno-associated virus (AAV) or nanoparticles (NP) via a trans-scleral and trans-choroidal approach. Careful positioning of the ...

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    8. The International Multiple Sclerosis Visual System Consortium: Advancing Visual System Research in Multiple Sclerosis

      The International Multiple Sclerosis Visual System Consortium: Advancing Visual System Research in Multiple Sclerosis

      Background: The International Multiple Sclerosis Visual System Consortium (IMSVISUAL) was formed in November 2014 with the primary goal of improving research, care, and education regarding the role of the visual system in multiple sclerosis (MS) and related disorders. Methods: In this review, we describe the formation, goals, activities, and structure of IMSVISUAL, as well as the relationship of IMSVISUAL with the Americas Committee for Treatment and Research in MS (ACTRIMS). Finally, we provide an overview of the work IMSVISUAL has completed to date, as well as an outline of research projects ongoing under the auspices of IMSVISUAL. Results: IMSVISUAL has ...

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    9. Anterior Segment Optical Coherence Tomography Angiography in a Patient With Persistent Pupillary Membrane

      Anterior Segment Optical Coherence Tomography Angiography in a Patient With Persistent Pupillary Membrane

      The image depicts a 60-year-old woman with bilateral cataracts and no history of amblyopia, strabismus, or systemic diseases. Color slitlamp photography of the left eye ( Figure , A) showed a persistent pupillary membrane, with multiple iris strands extending from collarette to collarette and adhering to the anterior lens surface. Anterior segment optical coherence tomography angiography ( Figure , B) showed vessels originating from the lesser arterial circle of the iris and anastomosing with one another centrally. Persistent pupillary membrane results from incomplete involution of the tunica vasculosa lentis, which supplies the epithelium of the lens during fetal development. 1

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    10. Systems and methods for retinal layer segmentation in OCT imaging and OCT angiography

      Systems and methods for retinal layer segmentation in OCT imaging and OCT angiography

      Disclosed herein are methods and systems for segmenting, visualizing, and quantifying the layered structure of retina in optical coherence tomography datasets. The disclosed methods have particular application to OCT angiography data, where specific retina layers have distinct vascular structures and characteristics that can be altered in various pathological conditions of the eye.

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    11. Can we Predict COronary Resistance By EYE Examination ? (COREYE)

      Can we Predict COronary Resistance By EYE Examination ? (COREYE)

      Prospective interventional study, open, non-comparative and non-randomized. The research concerns physiological parameters of the coronary and ocular blood circulation. At the coronary level, the curves of pressure and Doppler flow will be extracted from ComboMap® (Philips). The coronary microvascular resistances, basal and hyperemic, will be determined by the average ratio of the distal pressure and flow. At the ocular level, a fundus oculi and an OCTA (angiography by tomography in optical coherence) examination will be performed. The measures of the FFR and the coronary microvascular resistance will be determined by a specific guidewire allowing simultaneous measures of pressure and Doppler ...

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    12. Attenuation correction assisted automatic segmentation for assessing choroidal thickness and vasculature with swept-source OCT

      Attenuation correction assisted automatic segmentation for assessing choroidal thickness and vasculature with swept-source OCT

      Swept source optical coherence tomography (SS-OCT) is being used more widely in clinical studies to investigate the choroid due to its deeper penetration under the retinal pigment epithelium and improved image quality compared with spectral domain OCT. However, automatic methods to reliably assess choroidal thickness and vasculature are still limited. This paper reports an approach that applies attenuation correction on SS-OCT structural scans to facilitate accurate automatic segmentation of the choroid and provides visualization of the choroidal vasculature without the necessity of OCT angiography. After attenuation correction, enhanced interlayer contrast at the choroidal-scleral interface was observed (from 0.13 ± 0 ...

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    13. SS-OCT enables increased speed, deeper penetration, but steeper cost

      SS-OCT enables increased speed, deeper penetration, but steeper cost

      Swept source OCT has many benefits over spectral domain OCT, but its biggest obstacle today is cost, according to Jay S. Du k er at the American Academy of Optometry annual meeting. SS-OCT is a form of fourier domain detection, which is how the echo time delay is calculated in the device, he said. The SS light source is a tunable laser that rapidly changes the wavelength, which is very expensive, he added. The reflections of depth are detected with photodetectors, not with a camera as with SD-OCT. The longer wavelength of SS-OCT images (1,000 nm to 1,300 ...

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    14. The use of optical coherence tomography for the detection of ocular toxicity by ethambutol

      The use of optical coherence tomography for the detection of ocular toxicity by ethambutol

      Objectives To evaluate, through (OCT), alterations in retinal thickness, secondary to use of ethambutol in the treatment of patients with tuberculosis. In addition to studying the use of simpler semiological tools, such as Amsler and Ishihara, in the screening of these cases. Methods Thirty patients with ethambutol were recruited from the reference service of tuberculosis treatment at the Federal University of Espírito Santo from May 2015 to July 2016. After clinical history, the following parameters were analyzed; best corrected visual acuity, biomicroscopy, tonometry, photomotor reflex testing, Ishihara test, Amsler’s grid test, color digital retinography and optical coherence tomography ...

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    15. Retinal blood flow reduction after panretinal photocoagulation in Type 2 diabetes mellitus: Doppler optical coherence tomography flowmeter pilot study

      Retinal blood flow reduction after panretinal photocoagulation in Type 2 diabetes mellitus: Doppler optical coherence tomography flowmeter pilot study

      To use a Doppler optical coherence tomography (DOCT) flowmeter to investigate segmental retinal blood flow (RBF) and sum of the segmental RBFs (SRBF) changes after panretinal photocoagulation (PRP) was used to treat type 2 diabetes mellitus with severe diabetic retinopathy (DR). Data from five patients with proliferative DR (PDR) (mean age 51.9 ± 10.5 years) was analyzed. The vessel diameter (D), average velocity (V), and retinal blood flow (RBF) in veins were measured using a DOCT flowmeter before and four weeks after PRP. Segmental RBF from inferotemporal (IT), superotemporal (ST), inferonasal (IN), and superonasal (SN) veins were measured, and ...

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    16. Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography in Different Clinical Subtypes of Multiple Sclerosis

      Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography in Different Clinical Subtypes of Multiple Sclerosis

      Background Multiple sclerosis (MS) is a chronic inflammatory demyelinating autoimmune disease of the central nervous system (CNS) with axonal degeneration as major determinant of neurological disability. Assessment of unmyelinated retinal nerve fibers using optical coherence tomography (OCT) may be useful for diagnosing the onset and rate of progression of neurodegeneration. Objective To assess the incidence and severity of damage of the peripapillary retinal nerve fiber layer (RNFL) in two different MS subtypes: non-progressive [Prog(-)MS] and progressive [Prog(+)MS]. Methods 48 patients (96 eyes) with MS were included: 13 males, 35 females; aged 22-62 years (mean 38.8; SD ±10 ...

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    17. Usefulness of peripapillary nerve fiber layer thickness assessed by optical coherence tomography as a biomarker for Alzheimer’s disease

      Usefulness of peripapillary nerve fiber layer thickness assessed by optical coherence tomography as a biomarker for Alzheimer’s disease

      The use of optical coherence tomography (OCT) has been suggested as a potential biomarker for Alzheimer’s Disease based on previously reported thinning of the retinal nerve fiber layer (RNFL) in Alzheimer’s disease’s (AD) and Mild Cognitive Impairment (MCI). However, other studies have not shown such results. 930 individuals (414 cognitively healthy individuals, 192 probable amnestic MCI and 324 probable AD) attending a memory clinic were consecutively included and underwent spectral domain OCT (Maestro, Topcon) examinations to assess differences in peripapillary RNFL thickness, using a design of high ecological validity. Adjustment by age, education, sex and OCT image ...

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    18. Optical coherence tomography-angiography in the multimodal imaging of age-related macular degeneration – a review

      Optical coherence tomography-angiography in the multimodal imaging of age-related macular degeneration – a review

      Age-related macular degeneration is the leading cause of irreversible visual function loss in individuals from developed countries over the age of 65 years. The global prevalence of age-related macular degeneration is expected to increase by 50% in 2020 due to increased life expectancy and aging population worldwide. The central vision loss in the late stage of the disease – geographic atrophy and choroidal neovascularization is a serious social and economic problem. It requires regular screening, early diagnosis, and timely treatment. Оptical coherence tomography-angiography is a relatively new diagnostic method. Based on its noninvasiveness it is widely used in age-related macular degeneration.

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    19. Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography

      Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography

      Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in human studies, but no SAR-OCT system has been reported in detail for imaging the retinas of mice. An optical model of a mouse eye was designed and extended for validity at wavelengths of light around 1310 nm; this model was then utilized to develop a SAR-OCT design for murine retinal imaging. A Monte Carlo technique simulates ...

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    20. Peripapillary microvasculature in the retinal nerve fiber layer in glaucoma by optical coherence tomography angiography: focal structural and functional correlations and diagnostic performance

      Peripapillary microvasculature in the retinal nerve fiber layer in glaucoma by optical coherence tomography angiography: focal structural and functional correlations and diagnostic performance

      Purpose: To quantify peripapillary microvasculature within the retinal nerve fiber layer (RNFL) in primary open-angle glaucoma (POAG) and normal eyes, determine association of perfusion parameters with structural and functional measures, and report diagnostic accuracy of perfusion parameters. Patients and methods: POAG and normal patients underwent 6×6 mm2 optic nerve head scans (Angioplex optical coherence tomography angiography [OCTA]; Cirrus HD-OCT 5000) and Humphrey Field Analyzer II-i 24-2 visual field (VF) testing. Prototype software performed semiautomatic segmentation to create RNFL en face images and quantified vessel area density (VAD), vessel skeleton density (VSD), and vessel complexity index (VCI) in the optic ...

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    21. SD-OCT Detects Elusive Epiretinal Membrane

      SD-OCT Detects Elusive Epiretinal Membrane

      Researchers from Spain recommend practitioners perform spectral-domain optical coherence tomography (SD-OCT) before cataract surgery because fundus examination might not detect an epiretinal membrane. In their study, the membrane’s presence in the macular area with no foveal alterations was the only risk factor for pseudophakic cystoid macular edema (CME) and may implicate a previous subclinical damage or increased predisposition to both conditions. In a prospective cohort study, 112 patients underwent SD-OCT within one week pre-op and three months post-op. CME incidence in the cohort was 11.6% (13 eyes), all of which were diagnosed at one month, and seven eyes ...

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    22. Glaucoma Specialist Detection of Optical Coherence Tomography Suspicious Rim Tissue in Glaucoma and Glaucoma Suspect Eyes.

      Glaucoma Specialist Detection of Optical Coherence Tomography Suspicious Rim Tissue in Glaucoma and Glaucoma Suspect Eyes.

      Purpose To assess glaucoma specialists’ detection of optic nerve head (ONH) rim tissue that is thin by optical coherence tomography (OCT) criteria. Design Reliability analysis Methods 5 clinicians marked the disc margin (DM) and rim margin (RM) on stereo-photos of 151 glaucoma or glaucoma suspect eyes obtained within 3 months of OCT imaging. The photo and OCT infrared image for each eye were colocalized and regionalized into twelve sectors relative to the axis between Bruch’s membrane opening (BMO) centroid and the fovea. For each clinician, the distance from BMO centroid to their DM (DM radius) and RM (RM radius ...

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    23. Evaluation of Retinal Nerve Fiber Layer and Inner Macular Layers in Primary Open-Angle Glaucoma with Spectral-Domain Optical Coherence Tomography (Book Chapter)

      Evaluation of Retinal Nerve Fiber Layer and Inner Macular Layers in Primary Open-Angle Glaucoma with Spectral-Domain Optical Coherence Tomography (Book Chapter)

      Purpose: The aim of our research is to assess and compare the peripapillary retinal nerve fiber layer (pRNFL) thickness diagnostic capability with those of three macular parameters—macular RNFL (mRNFL) thickness, GCL+ (ganglion cell layer with inner plexiform layer thickness), and GCL++ (mRNFL and GCL+) in primary open-angle glaucoma patients with spectral-domain optical coherence tomography (SD-OCT). Material and methods: The 414 participants (483 eyes) aged 45–84 years in this prospective study were recruited from Eye Clinic at the University Hospital “Alexandrovska” (Sofia, Bulgaria). They were divided into 6 groups: controls, ocular hypertension, preperimetric glaucoma (PPG), and three groups of ...

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