1. Articles in category: Ophthalmology

    49-72 of 11881 « 1 2 3 4 5 6 ... 493 494 495 »
    1. Detection of missampled interferograms in frequency domain OCT with a k-clock

      Detection of missampled interferograms in frequency domain OCT with a k-clock

      Optical coherence tomography light sources can be non-linear and attempts to linearize them can lead to asynchrony between the light source and A-line scans and missampling in the scans causing signal noise. Accordingly, a system and methods are provided herein to detect missampling by obtaining a plurality of interferograms; providing at least two wavenumber reference signals at different wavenumbers, wherein the wavenumber reference signals comprise attenuated or enhanced portions of each of the plurality of interferograms; aligning each of the plurality of interferograms according to one of the at least two wavenumber reference signals; and for each of the plurality ...

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    2. Posterior staphylomas and scleral curvature in highly myopic children and adolescents investigated by ultra-widefield optical coherence tomography

      Posterior staphylomas and scleral curvature in highly myopic children and adolescents investigated by ultra-widefield optical coherence tomography

      Purpose To determine the early signs of posterior staphylomas in highly myopic eyes of younger subjects by swept-source ultra-widefield optical coherence tomography (WF-OCT). Methods This was an observational case series study. Highly myopic subjects younger than 20 years old who were examined consecutively by prototype WF-OCT were studied. High myopia was defined according to the Ministry of Health and Welfare, Japan classification. A posterior displacement of the sclera and two OCT features indicating the staphyloma edges were used as markers of a staphyloma. Results Fifty-five eyes of 30 patients with the mean age of 12.3 years, and the mean ...

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    3. Diurnal Choroidal Variations Detected by OCT-A

      Diurnal Choroidal Variations Detected by OCT-A

      Upon investigating the diurnal changes of choroidal sublayer perfusion in normal eyes and identifying influencing factors using optical coherence tomography angiography (OCT-A), German researchers found that OCTA-based analysis demonstrated significant diurnal variations in choroidal sublayer perfusion. The prospective study evaluated 22 healthy volunteers who underwent repeated measurements of subfoveal choroidal thickness with enhanced-depth-imaging OCT as well as perfusion of choroidal vascular sublayers using OCT-A at 7am, 12pm, 4pm and 8pm. The team looked into possible interactions between diurnal variations and other factors, such as mean arterial pressure, gender and age. The study authors observed a significant pattern of diurnal variation ...

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    4. Optical Coherence Tomography Angiography to Assess Vascular Remodeling of the Choriocapillaris After Low-Fluence Photodynamic Therapy for Chronic Central Serous Chorioretinopathy

      Optical Coherence Tomography Angiography to Assess Vascular Remodeling of the Choriocapillaris After Low-Fluence Photodynamic Therapy for Chronic Central Serous Chorioretinopathy

      Background To evaluate the efficacy of optical coherence tomography angiography (OCTA) in identifying changes in the choriocapillaris layer after low-fluence verteporfin photodynamic therapy (vPDT) in patients affected by chronic central serous chorioretinopathy (CSCR). Methods Low-fluence vPDT was performed on 28 eyes of 27 patients with CSCR. All patients underwent the following tests at baseline and 6 months after treatment: best corrected visual acuity (BCVA), fluorescein angiography, indocyanine green angiography, enhanced depth imaging OCT and OCTA. Results Subretinal fluid was completely absorbed in 18 of the 28 affected eyes (64.3%) after low-fluence vPDT (“responders”), and incompletely absorbed in 10 eyes ...

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    5. Automatic Classification of Retinal Optical Coherence Tomography Images With Layer Guided Convolutional Neural Network

      Automatic Classification of Retinal Optical Coherence Tomography Images With Layer Guided Convolutional Neural Network

      Optical coherence tomography (OCT) enables instant and direct imaging of morphological retinal tissue and has become an essential imaging modality for ophthalmology diagnosis. As one of the important morphological retinal characteristics, the structural information of retinal layers provides meaningful diagnostic information and is closely related to several retinal diseases. In this letter, we propose a novel layer guided convolutional neural network (LGCNN) to identify normal retina and three common types of macular pathologies, namely, diabetic macular edema, drusen, and choroidal neovascularization. Specifically, an efficient segmentation network is first employed to generate the retinal layer segmentation maps, which can delineate two ...

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    6. Segmentation of Retinal Cysts From Optical Coherence Tomography Volumes Via Selective Enhancement

      Segmentation of Retinal Cysts From Optical Coherence Tomography Volumes Via Selective Enhancement

      Automated and accurate segmentation of cystoid structures in optical coherence tomography (OCT) is of interest in the early detection of retinal diseases. It is, however, a challenging task. We propose a novel method for localizing cysts in 3-D OCT volumes. The proposed work is biologically inspired and based on selective enhancement of the cysts, by inducing motion to a given OCT slice. A convolutional neural network is designed to learn a mapping function that combines the result of multiple such motions to produce a probability map for cyst locations in a given slice. The final segmentation of cysts is obtained ...

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    7. OCT Signs Associated With Fellow Eye AMD Progression

      OCT Signs Associated With Fellow Eye AMD Progression

      Researchers confirmed that four previously reported optical coherence tomography (OCT) risk factors were associated with progression to late age-related macular degeneration (AMD) in the fellow eyes of participants newly diagnosed with macular neovascularization. This multicenter, prospective, randomized, double-masked, active treatment-controlled phase 3 clinical trial evaluated 501 eyes of 501 patients with macular neovascularization secondary to neovascular AMD and early or intermediate AMD in the fellow eye. The team reviewed OCT scans and assessed baseline features, including intraretinal hypereflective foci (IHRF), hyporeflective foci (hRF) within drusenoid lesions (DLs), subretinal drusenoid deposits (SDDs) and drusen volume (DV) ≥ 0.03 mm 3 . Masked ...

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    8. Comparison of foveal avascular zone between optical coherence tomography angiography and fluorescein angiography in patients with retinal vein occlusion

      Comparison of foveal avascular zone between optical coherence tomography angiography and fluorescein angiography in patients with retinal vein occlusion

      Objective To compare area of foveal avascular zone (FAZ) in different retinal vascular layers in optical coherence tomography angiography (OCTA) and fluorescein angiography (FA) in patients with retinal vein occlusion (RVO). Design and methods Prospective cross-sectional comparative study in 47 eyes of 47 patients. FA was recorded with the Zeiss FF450plusIR camera and OCTA was obtained with the Zeiss Cirrus 5000 equipped with the AngioPlex module. Area of FAZ was graded by two independent investigators and calculated with Adobe Photoshop. Analysis for the total study population as well as subgroup analysis for branch retinal vein occlusion (BRVO), central retinal vein ...

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    9. Measuring mechanical wave speed, dispersion, and viscoelastic modulus of the cornea using optical coherence elastography

      Measuring mechanical wave speed, dispersion, and viscoelastic modulus of the cornea using optical coherence elastography

      Acoustic wave velocity measurement based on optical coherence tomography (OCT) is a promising approach to assess the mechanical properties of biological tissues and soft materials. While studies to date have demonstrated proof of concept of different ways to excite and detect mechanical waves, the quantitative performance of this modality as mechanical measurement has been underdeveloped. Here, we investigate the frequency dependent measurement of the wave propagation in viscoelastic tissues, using a piezoelectric point-contact probe driven with various waveforms. We found that a frequency range of 2–10 kHz is a good window for corneal elastography, in which the lowest-order flexural ...

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    10. Intraoperative optical coherence tomographic findings may predict postoperative visual outcome in eyes with idiopathic macular hole

      Intraoperative optical coherence tomographic findings may predict postoperative visual outcome in eyes with idiopathic macular hole

      Purpose To determine the significance of the correlation between the intraoperative optical coherence tomographic (OCT) findings and the postoperative retinal morphology and physiology in eyes with an idiopathic macular hole (MH). Design Retrospective interventional case control study. Subjects Pars plana vitrectomy with internal limiting membrane (ILM) peeling and air tamponade was performed on 33 eyes with idiopathic MHs. All of the eyes were followed for at least 6 months. Methods The intraoperative OCT (Rescan, Carl Zeiss Meditec) images were used to detect the presence of residual fragments at the edge of the MH, and the eyes were divided into those ...

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    11. Assessment of posterior capsular integrity on optical coherence tomography

      Assessment of posterior capsular integrity on optical coherence tomography

      The integrity of posterior capsule is of paramount importance to cataract surgeon. Careful preoperative assessment is routinely performed to avoid undesirable intraoperative complications. Routine slit-lamp-based assessment provides a detailed understanding of the posterior capsule, provided that lens matter is optically clear to an acceptable extent. However, the presence of opacity along the posterior capsule with a hidden defect such as posterior polar cataract may pose a challenge to decipher the intactness of the capsule. 1 Under such circumstances, noninvasive imaging modalities, such as anterior segment optical coherence tomography (OCT), is at surgeons rescue during the preoperative period. Therefore, here we ...

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    12. Optical coherence tomography angiography of perilimbal vasculature: validation of a standardised imaging algorithm

      Optical coherence tomography angiography of perilimbal vasculature: validation of a standardised imaging algorithm

      Purpose To test the reliability and accuracy of a standardised non-invasive imaging algorithm using optical coherence tomography angiography (OCTA) in detecting and quantifying pharmacologically induced changes in the perilimbal vasculature. Methods In this prospective observational imaging study, 370 angiograms of 15 normal eyes and 10 eyes with nasal pterygiums were obtained using a commercially available OCTA system with split-spectrum amplitude-decorrelation angiography technology. Postprocessing of the images to quantify the area occupied by the blood vessels was performed using the Fiji software. The main outcome measures were reliability (intraobserver and interobserver agreement) and accuracy of the standardised algorithm in detecting and ...

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    13. Pars plana vitrectomy with intraoperative optical coherence tomography for sub-internal limiting membrane fibrosis excision in a child with Terson syndrome: Surgical and pathological correlation

      Pars plana vitrectomy with intraoperative optical coherence tomography for sub-internal limiting membrane fibrosis excision in a child with Terson syndrome: Surgical and pathological correlation

      Purpose To report the intraoperative optical coherence tomography (OCT)-guided surgery of a consolidated sub-internal limiting membrane (ILM) hemorrhage that developed into a sub-ILM fibrotic membrane in a child with a history of Terson syndrome. Observations A one year-old boy with a history of Terson syndrome due to a motor vehicle accident presented three months after trauma with a white feather-shaped membrane in the left macula. Preoperative OCT showed a preretinal hyperreflective tissue at the foveal center. The patient underwent pars plana vitrectomy. After separation of the posterior hyaloid, intraoperative OCT did not show any change in structural components. After ...

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    14. Automated Measurement of the Foveal Avascular Zone in Swept-Source Optical Coherence Tomography Angiography Images

      Automated Measurement of the Foveal Avascular Zone in Swept-Source Optical Coherence Tomography Angiography Images

      Purpose : The purpose of this study was to evaluate automated measurement of the foveal avascular zone (FAZ) area using the Kanno-Saitama macro (KSM) software in Image J with swept-source optical coherence tomography angiography (SS-OCTA) images. Methods : In this cross-sectional study, one photographer scanned the macular area (3 × 3 mm) of healthy volunteers twice on the same day, at the same time. The FAZ area was measured from the en face image of the superficial retinal layer by two masked examiners, using the KSM and the Advanced Retina Imaging (ARI)-network method in Carl Zeiss online analysis. Intra- and interscan reproducibility ...

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    15. In Vivo Mapping of the Choriocapillaris in Healthy Eyes: a Widefield Swept Source Optical Coherence Tomography Angiography Study

      In Vivo Mapping of the Choriocapillaris in Healthy Eyes: a Widefield Swept Source Optical Coherence Tomography Angiography Study

      Purpose To report variation of choriocapillaris (CC) flow in peripapillary, macular and near/mid periphery regions in healthy subjects using widefield swept source optical coherence tomography angiography (SS-OCTA). Design Prospective, cross-sectional study. Subjects Fifty healthy subjects. Methods Healthy young subjects were imaged with the SS-OCTA system (PLEX Elite 9000, Carl Zeiss Meditec Inc., Dublin, CA, USA). OCTA scans were taken in primary and extremes of gaze and a montage was automatically created. The en face CC images were then exported to imageJ and a semi-automated algorithm was used for subsequent quantitative analysis. Main outcome measures Quantitative analysis of the CC ...

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    16. Time course of swept-source optical coherence tomography angiography findings after photodynamic therapy and aflibercept in eyes with age-related macular degeneration

      Time course of swept-source optical coherence tomography angiography findings after photodynamic therapy and aflibercept in eyes with age-related macular degeneration

      Purpose To report swept-source optical coherence tomography angiography (SS-OCTA) findings after full-fluence photodynamic therapy (PDT) and aflibercept intravitreal injection (IVA) for age-related macular degeneration (AMD). Methods Five eyes of five patients with AMD treated with PDT and IVA were include into the study. We retrospectively reviewed the data obtained from the five patients using SS-OCTA before and after treatment. Three eyes had type 1 choroidal neovascularization (CNV) and two eyes had polypoidal choroidal vasculopathy. Results Before treatment, the CNV signals detected in all cases, decreased in three eyes and were not detected completely in two eyes at 1 months after ...

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      Mentions: Osaka University
    17. Performance of the “Rule of 5” for Detecting Glaucoma Progression Between Visits with Optical Coherence Tomography

      Performance of the “Rule of 5” for Detecting Glaucoma Progression Between Visits with Optical Coherence Tomography

      Purpose To evaluate whether loss of 5 μm in global retinal nerve fiber layer (RNFL) thickness on spectral-domain optical coherence tomography (SDOCT) between two consecutive visits is specific for glaucoma progression. Design Prospective cohort. Participants 92 eyes in 49 controls and 300 eyes in 210 glaucoma subjects. Methods Study subjects completed at least five standard automated perimetry and SDOCT examinations at 6-month intervals over at least 2 years. Eyes were categorized as progressing from glaucoma if the average RNFL declined by 5 μm between two consecutive visits. The false positive proportion was estimated by two methods: 1) 5 μm loss ...

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    18. Duke University Receives NIH Grant for Handheld Confocal Scanning Laser Ophthalmoscope for Remote Screening of Diabetic Retinopathy

      Duke University Receives NIH Grant for Handheld Confocal Scanning Laser Ophthalmoscope for Remote Screening of Diabetic Retinopathy

      Duke University Receives a 2019 NIH Grant for $233,465 for Handheld Confocal Scanning Laser Ophthalmoscope for Remote Screening of Diabetic Retinopathy. The principal investigator is Joseph Izatt. The program began in 2019 and ends in 2021. Below is a summary of the proposed work. This is an application for an Exploratory/Developmental Research Grant which brings together a team of engineers and clinician-scientists with expertise in ophthalmic imaging technology development and translation to advance the state of the art remote screening for diabetic retinopathy (DR). Diabetic retinopathy (DR) is a complication from diabetes mellitus (DM) that causes damage to ...

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    19. Duke University Receives NIH Grant for Portable Stabilized Optical Coherence Tomography for Eye Care in Acute Care Settings

      Duke University Receives NIH Grant for Portable Stabilized Optical Coherence Tomography for Eye Care in Acute Care Settings

      Duke University Receives a 2019 NIH Grant for $384,440 for Portable Stabilized Optical Coherence Tomography for Eye Care in Acute Care Settings. The principal investigator is Anthony Kuo The program began in 2018 and ends in 2021. Below is a summary of the proposed work. This research proposal from a multi-disciplinary team including an emergency medicine physician, ophthalmologists, and biomedical engineers seeks to improve the ability of acute care providers to diagnose and triage eye pathology at the point of care. Acute care settings such as emergency departments frequently take care of patients seeking eye care. In these acute ...

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    20. Johns Hopkins University Receives NIH Grant for Eye Determinants of Cognition (EYEDOC) study.

      Johns Hopkins University Receives NIH Grant for Eye Determinants of Cognition (EYEDOC) study.

      Johns Hopkins University Receives a 2019 NIH Grant for $395,304 for Eye Determinants of Cognition (EYEDOC) study. The principal investigator is Alison Abraham. The program began in 2016 and ends in 2020. Below is a summary of the proposed work. Eye Determinants of Cognition (EyeDOC) Study Rationale: Dementia and mild cognitive impairment (MCI) pose enormous health and societal costs in our aging US population. While cerebral neural loss is known to contribute to Alzheimer's dementia, vascular diseases may contribute substantially to the total burden of dementia and its precursor, MCI. Small-vessel cerebrovascular changes, which are most strongly associated ...

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    21. Systems and methods for quantitative doppler optical coherence tomography

      Systems and methods for quantitative doppler optical coherence tomography

      Methods of obtaining a measure of blood flow using a Fourier domain optical coherence tomography (FDOCT) system is provided. The method includes obtaining a first optical coherence tomography (OCT) survey scan of a retina of a subject using an OCT scan beam and obtaining a second OCT scan of the retina. The second OCT scan is within an area defined by the obtained first OCT scan and includes a region of retinal blood vessels emerging from and returning to an Optic Nerve Head (ONH) of the retina. An optical phase change is determined from the obtained second OCT scan, the ...

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    22. Application of optical coherence tomography and optical path length method for monitoring corneal thickness and refractive index change during corneal cross-linking

      Application of optical coherence tomography and optical path length method for monitoring corneal thickness and refractive index change during corneal cross-linking

      Corneal cross-linking (CXL) using UVA irradiation with a riboflavin photosensitizer has emerged as a new treatment paradigm for corneal ectatic disorders. The thickness threshold for protection of intraocular structures has often been challenged with ongoing developments, and corneal thinning becomes an important safety concern, especially for patients with thin corneas. In this study with an ex vivo bovine eye model, we monitored corneal thinning and corneal refractive index changes using optical coherence tomography (OCT) integrated with an adaptation of the optical path length method. CXL experiments were performed based on the standard protocol that includes removal of the corneal epithelium ...

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