1. 1-24 of 244 1 2 3 4 ... 9 10 11 »
    1. Corneal Lenticule Creation Using a New Solid-State Femtosecond Laser Measured by Spectral Domain OCT in a Porcine Eye Model

      Purpose: To determine the accuracy and precision of corneal lenticule creation with a new solid-state femtosecond laser in a porcine eye model. Methods: Corneal lenticule creation was performed using a new solid-state femtosecond laser on 60 porcine eyes with 10 subgroups. Optical coherence tomography images were acquired immediately after laser treatment. Cap thickness (CT), cap diameter (CD), and lenticule thickness (LT) were measured manually by three independent readers. Additionally, CT and LT were measured by an automated algorithm (aLT, aCT). Results: Measured LT was significantly greater than the intended LT (average difference 14.3 ± 5.6 µm, P < 0.001 ...

      Read Full Article
    2. Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

      Correlation Between Laser Speckle Flowgraphy and OCT-Derived Retinal and Choroidal Metrics in Healthy Human Eye

      Purpose: To investigate the correlation between laser speckle flowgraphy (LSFG) signals and the quantitative metrics derived from optical coherence tomography (OCT) in normal eyes. Methods: LSFG, OCT, and OCT angiography (OCTA) imaging were performed on normal participants using a custom-designed LSFG system and a commercial swept-source OCT system. Mean (PWM) and amplitude (PWA) of the LSFG pulse waveform were selected to quantify the LSFG signals. Retinal and choroidal maps were obtained using the standard 6 × 6 mm OCT and OCTA scans. Structural and vascular metrics maps, including thickness, vessel area density, vessel skeleton density, and vessel diameter index of the ...

      Read Full Article
    3. Quantitative Assessment of Biomechanical Properties of the Human Keratoconus Cornea Using Acoustic Radiation Force Optical Coherence Elastography

      Quantitative Assessment of Biomechanical Properties of the Human Keratoconus Cornea Using Acoustic Radiation Force Optical Coherence Elastography

      Purpose: Quantification of biomechanical properties of keratoconus (KC) corneas has great significance for early diagnosis and treatment of KC, but the corresponding clinical measurement remains challenging. Here, we developed an acoustic radiation force (ARF) optical coherence elastography technique and explored its potential for evaluating biomechanical properties of KC corneas. Methods: An ARF system was used to induce the tissue deformation, which was detected by an optical coherence tomography system, and thus the localized point-by-point Young's modulus measurements were achieved. Then, two healthy rabbit eyes were imaged to test the system, after which the human keratoconus cornea was evaluated by ...

      Read Full Article
    4. Macular Vascular Imaging and Connectivity Analysis Using High-Resolution Optical Coherence Tomography

      Macular Vascular Imaging and Connectivity Analysis Using High-Resolution Optical Coherence Tomography

      Purpose: To characterize macular blood flow connectivity in vivo using high-resolution optical coherence tomography (HighRes OCT). Methods: Cross-sectional, observational study. Dense (6-µm interscan distance) perifoveal HighRes OCT raster scans were performed on healthy participants. To mitigate the limitations of projection-resolved OCT-angiography, flow and structural data were used to observe the vascular structures of the superficial vascular complex (SVC) and the deep vascular complex. Vascular segmentation and rendering were performed using Imaris 9.5 software. Inflow and outflow patterns were classified according to vascular diameter and branching order from superficial arteries and veins, respectively. Results: Eight eyes from eight participants ...

      Read Full Article
    5. Dynamic Contrast Microscopic Optical Coherence Tomography As a Novel Method for Assessing Corneal Epithelium During Exposure to Benzalkonium Chloride

      Dynamic Contrast Microscopic Optical Coherence Tomography As a Novel Method for Assessing Corneal Epithelium During Exposure to Benzalkonium Chloride

      Purpose: Microscopic optical coherence tomography (mOCT) has an imaging resolution of 1 µm in all voxel dimensions, but individual epithelial cells are difficult to resolve due to lack of scattering contrast. Adding dynamic contrast processing to mOCT (dmOCT) results in color images that enable visualization of individual cells and possibly give information on cellular function via the calculation of a motility coefficient. We propose this technique as a novel method of evaluating the ocular surface after exposure to a toxic chemical, benzalkonium chloride (BAK). Methods: Ex vivo cross-section images were acquired with a custom-built, frequency-domain mOCT system. Eyes were explanted ...

      Read Full Article
    6. Prediction of Retinal Ganglion Cell Counts Considering Various Displacement Methods From OCT-Derived Ganglion Cell-Inner Plexiform Layer Thickness

      Prediction of Retinal Ganglion Cell Counts Considering Various Displacement Methods From OCT-Derived Ganglion Cell-Inner Plexiform Layer Thickness

      Purpose: To compare various displacement models using midget retinal ganglion cell to cone (mRGC:C) ratios and to determine viability of estimating RGC counts from optical coherence tomography (OCT)-derived ganglion cell-inner plexiform layer (GCIPL) measurements. Methods: Four Drasdo model variations were applied to macular visual field (VF) stimulus locations: (1) using meridian-specific Henle fiber length along the stimulus circumference; (2) using meridian-specific differences in RGC receptive field and counts along the stimulus circumference; (3) per method (2), averaged across principal meridians; and (4) per method (3), with the stimulus center displaced only. The Sjöstrand model was applied (5 ...

      Read Full Article
    7. Ocular Factors of Fractal Dimension and Blood Vessel Tortuosity Derived From OCTA in a Healthy Chinese Population

      Ocular Factors of Fractal Dimension and Blood Vessel Tortuosity Derived From OCTA in a Healthy Chinese Population

      Purpose: To identify the ocular factors of microvascular fractal dimension (FD) and blood vessel tortuosity (BVT) of macula measured with optical coherence tomography angiography (OCTA) in a healthy Chinese population. Methods: Healthy subjects without ocular disorders were recruited at Zhongshan Ophthalmic Center. The FD and BVT in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) at the macula were obtained from OCTA images. The FD was calculated using the box-counting method, and the BVT was defined as the ratio of the actual distance between two points to the straight distance on the skeletonized image. Univariate and stepwise multivariate ...

      Read Full Article
    8. 3D Microstructure of the Healthy Non-Human Primate Lamina Cribrosa by Optical Coherence Tomography Imaging

      3D Microstructure of the Healthy Non-Human Primate Lamina Cribrosa by Optical Coherence Tomography Imaging

      Purpose: The lamina cribrosa (LC) has an important role in the pathophysiology of ocular diseases. The purpose of this study is to characterize in vivo, noninvasively, and in 3D the structure of the LC in healthy non-human primates (NHPs). Methods: Spectral-domain optical coherence tomography (OCT; Leica, Chicago, IL) scans of the optic nerve head (ONH) were obtained from healthy adult rhesus macaques monkeys. Using a previously reported semi-automated segmentation algorithm, microstructure measurements were assessed in central and peripheral regions of an equal area, in quadrants and depth-wise. Linear mixed-effects models were used to compare parameters among regions, adjusting for visibility ...

      Read Full Article
    9. Assessment of Anterior Uveitis Through Anterior-Segment Optical Coherence Tomography and Artificial Intelligence-Based Image Analyses

      Assessment of Anterior Uveitis Through Anterior-Segment Optical Coherence Tomography and Artificial Intelligence-Based Image Analyses

      Purpose : The purpose of this study was to develop an automated artificial intelligence (AI) based method to quantify inflammation in the anterior chamber (AC) using anterior-segment optical coherence tomography (AS-OCT) and to explore the correlation between AI assisted AS-OCT based inflammation analyses and clinical grading of anterior uveitis by Standardization of Uveitis Nomenclature (SUN). Methods : A prospective double blinded study of AS-OCT images of 32 eyes of 19 patients acquired by Tomey CASIA-II. OCT images were analyzed with proprietary AI-based software. Anatomic boundaries of the AC were segmented automatically by the AI software and Spearman's rank correlation between parameters ...

      Read Full Article
    10. Detection of Early Glaucomatous Damage: Performance of Summary Statistics From Optical Coherence Tomography and Perimetry

      Detection of Early Glaucomatous Damage: Performance of Summary Statistics From Optical Coherence Tomography and Perimetry

      Purpose: To evaluate the diagnostic performance of optical coherence tomography (OCT) and visual field (VF) summary statistics (metrics) that are available in OCT and VF reports. Methods: OCT disc and macular scans and 24-2 and 10-2 VFs were obtained from 56 healthy control (HC) eyes/participants and 61 eyes/patients with 24-2 mean deviation of better than -6 dB. All metrics were obtained from OCT radial, circle, and posterior pole cube scans and 24-2 and 10-2 VFs. Their diagnostic performances were evaluated, in isolation and in combinations. For specificity, the 56 HC eyes were used. For sensitivity, 40 of the ...

      Read Full Article
    11. Assessment of Diabetic Choroidopathy Using Ultra-Widefield Optical Coherence Tomography

      Assessment of Diabetic Choroidopathy Using Ultra-Widefield Optical Coherence Tomography

      Purpose: The purpose of this study was to investigate a confocal scanning laser ophthalmoscopy (cSLO) ultra-widefield (UWF) swept-source optical coherence tomography (S-SOCT) in assessment of diabetic choroidopathy and to evaluate the agreement of measurements with a spectral-domain OCT (SD-OCT) instrument. Methods: We conducted a cross-sectional study of patients with diabetes evaluating the choroidal vascularity index (CVI) in the nasal, temporal, and central macula segments of a UWF SS-OCT scan centered to the fovea. UWF pseudocolored fundus images were used for diabetic retinopathy (DR) severity staging. The CVI values were compared between different degrees of severity of DR and different posterior-pole ...

      Read Full Article
    12. The OCT RNFL Probability Map and Artifacts Resembling Glaucomatous Damage

      The OCT RNFL Probability Map and Artifacts Resembling Glaucomatous Damage

      Purpose: The purpose of this study was to improve the diagnostic ability of the optical coherence tomography (OCT) retinal nerve fiber layer (RNFL) probability (p-) map by understanding the frequency and pattern of artifacts seen on the p-maps of healthy control (HC) eyes resembling glaucomatous damage. Methods: RNFL p-maps were generated from wide-field OCT cube scans of 2 groups of HC eyes, 200 from a commercial normative group (HC-norm) and 54 from a prospective study group, as well as from 62 patient eyes, which included 32 with early glaucoma (EG). These 32 EG eyes had 24-2 mean deviation (MD) better ...

      Read Full Article
    13. Evaluation of Ocular Biometric and Optical Coherence Tomography Parameters in Preterm Children Without Retinopathy of Prematurity

      Evaluation of Ocular Biometric and Optical Coherence Tomography Parameters in Preterm Children Without Retinopathy of Prematurity

      Purpose: To evaluate and compare biometric and optical coherence tomography parameters of ocular structures in preterm children without retinopathy of prematurity with term children. Methods: A cross-sectional, comparative study was carried out from 2018 to 2019. In this study, 124 eyes of 62 preterm children were compared with 132 eyes of 66 term children aged between 7 and 9 years. Preterm children were born at 28 to 32 weeks with a birth weight of less than 2 kg with no ocular abnormalities, and term children were delivered at 37 or greater weeks and had a birth weight of 2 kg ...

      Read Full Article
    14. Corneal Epithelial Mapping Characteristics in Normal Eyes Using Anterior Segment Spectral Domain Optical Coherence Tomography

      Corneal Epithelial Mapping Characteristics in Normal Eyes Using Anterior Segment Spectral Domain Optical Coherence Tomography

      Purpose: The detailed mapping characteristics of the corneal epithelial thickness (CET) in normal eyes from a Middle Eastern population were investigated in relation to age, sex, intraocular pressure, and keratometric power (K). Methods: A retrospective cross-sectional and analytical study was conducted using spectral domain optical coherence tomography (OCT). We calculated the CET in 124 subjects in 17 zones within a 6 mm circle. Exclusion criteria included subjects with dry eyes, keratoconus, previous eye surgery, glaucoma, and irregular corneas. Results: A total of 124 individuals was composed of 64 males and 60 females. The mean age of this population was 45 ...

      Read Full Article
    15. Evaluation of an OCT-AI-Based Telemedicine Platform for Retinal Disease Screening and Referral in a Primary Care Setting

      Evaluation of an OCT-AI-Based Telemedicine Platform for Retinal Disease Screening and Referral in a Primary Care Setting

      Purpose: To evaluate the performance of a telemedicine platform integrated with optical coherence tomography (OCT) and artificial intelligence (AI) techniques for retinal disease screening and referral. Methods: We constructed an OCT-AI-based telemedicine platform and deployed it at four primary care stations located in Jing'an district, Shanghai, to detect retinal disease cases among aged groups and refer them to Shanghai Tenth People's Hospital (TENTH Hospital). Two ophthalmologists jointly graded the data set collected from this pilot application, and then the performance of this platform was analyzed from multiple aspects. Results: This study included 1257 participants between July 2020 and ...

      Read Full Article
    16. Application of Artificial Intelligence and Deep Learning for Choroid Segmentation in Myopia

      Application of Artificial Intelligence and Deep Learning for Choroid Segmentation in Myopia

      Purpose : To investigate the correlation between choroidal thickness and myopia progression using a deep learning method. Methods : Two data sets, data set A and data set B, comprising of 123 optical coherence tomography (OCT) volumes, were collected to establish the model and verify its clinical utility. The proposed mask region-based convolutional neural network (R-CNN) model, trained with the pretrained weights from the Common Objects in Context database as well as the manually labeled OCT images from data set A, was used to automatically segment the choroid. To verify its clinical utility, the mask R-CNN model was tested with data set ...

      Read Full Article
    17. Bleb Analysis Using Anterior Segment Optical Coherence Tomography and Surgical Predictors of XEN Gel Stent

      Bleb Analysis Using Anterior Segment Optical Coherence Tomography and Surgical Predictors of XEN Gel Stent

      Purpose: To determine the early predictors of surgical success 6 months after XEN surgery among clinical parameters, including anterior segment optical coherence tomography (AS-OCT). Methods: A total of 31 eyes with medically uncontrolled primary open-angle glaucoma or pseudoexfoliation glaucoma was enrolled retrospectively. Using AS-OCT, XEN tip location was categorized into intraconjunctival, intratenon, or uviform at day 1 and blebs were classified into no or low, high sparse, high thick, cystic, or mixed walls at month 6. Using slit-lamp photography, blebs were classified into no or low, localized avascular, diffuse avascular, localized vascular, or diffuse vascular blebs at month 6. Surgical ...

      Read Full Article
    18. Application of Deep Learning Methods for Binarization of the Choroid in Optical Coherence Tomography Images

      Application of Deep Learning Methods for Binarization of the Choroid in Optical Coherence Tomography Images

      Purpose: The purpose of this study was to develop a deep learning model for automatic binarization of the choroidal tissue, separating choroidal blood vessels from nonvascular stromal tissue, in optical coherence tomography (OCT) images from healthy young subjects. Methods: OCT images from an observational longitudinal study of 100 children were used for training, validation, and testing of 5 fully semantic networks, which provided a binarized output of the choroid. These outputs were compared with ground truth images, generated from a local binarization technique after manually optimizing the analysis window size for each individual image. The performance was evaluated using accuracy ...

      Read Full Article
    19. Axial Stretching of Vessels in the Retinal Vascular Plexus With 3D OCT-Angiography

      Axial Stretching of Vessels in the Retinal Vascular Plexus With 3D OCT-Angiography

      Purpose: The purpose of this study is to describe and quantify the nonpathological axial stretching in the retinal vascular plexus in three-dimensional (3D) optical coherence tomography angiography (OCTA) images. Methods: The 3D vascular network underneath the inner limiting membrane of OCTA volumes was labeled as ground truth (GT) data. To analyze the cross-section area of the vessels the width and depth of the vessels in the GT data were computed and an elliptical quotient was proposed to quantify the axial stretching. Results: A total of 21 3D OCTA volumes were labeled. It was found that the vessels in 3D OCTA ...

      Read Full Article
    20. Development of a β-Variational Autoencoder for Disentangled Latent Space Representation of Anterior Segment Optical Coherence Tomography Images

      Development of a β-Variational Autoencoder for Disentangled Latent Space Representation of Anterior Segment Optical Coherence Tomography Images

      Purpose: To investigate the feasibility of extracting a low-dimensional latent structure of anterior segment optical coherence tomography (AS-OCT) images by use of a β-variational autoencoder (β-VAE). Methods: We retrospectively collected 2111 AS-OCT images from 2111 eyes of 1261 participants from the ongoing Asan Glaucoma Progression Study. After hyperparameter optimization, the images were analyzed with β-VAE. Results: The mean participant age was 64.4 years, with mean values of visual field index and mean deviation of 86.4% and -5.33 dB, respectively. After experiments, a latent space size of 6 and β value of 53 were selected for latent space analysis ...

      Read Full Article
    21. Comparisons Among Optical Coherence Tomography and Fundus Autofluorescence Modalities as Measurements of Atrophy in ABCA4-Associated Disease

      Comparisons Among Optical Coherence Tomography and Fundus Autofluorescence Modalities as Measurements of Atrophy in ABCA4-Associated Disease

      Purpose: In ABCA4-associated retinopathy, central atrophy was assessed by spectral domain optical coherence tomography (SD-OCT) and by short-wavelength (SW-AF) and near-infrared (NIR-AF) autofluorescence. Methods: Patients exhibited a central atrophic lesion characterized by hypoautofluorescence (hypoAF) surrounded either by hyperautofluorescent (hyperAF) rings in both AF images (group 1, 4 patients); or a hyperAF ring in SW-AF but not in NIR-AF images (group 2, 11 patients); or hyperAF rings in neither AF images (group 3, 11 patients). Choroidal hypertransmission and widths of ellipsoid zone (EZ) loss were measured in foveal SD-OCT scans, and in AF images hypoAF and total hypo+hyperAF widths were ...

      Read Full Article
    22. Noninvasive Estimation of Pulsatile and Static Intracranial Pressure by Optical Coherence Tomography

      Noninvasive Estimation of Pulsatile and Static Intracranial Pressure by Optical Coherence Tomography

      Purpose: To explore the ability of optical coherence tomography (OCT) to noninvasively estimate pulsatile and static intracranial pressure (ICP). Methods: An OCT examination was performed in patients who underwent continuous overnight monitoring of the pulsatile and static ICP for diagnostic purpose. We included two patient groups, patients with idiopathic intracranial hypertension (IIH; n = 20) and patients with no verified cerebrospinal fluid disturbances (reference; n = 12). Several OCT parameters were acquired using spectral-domain OCT (RS-3000 Advance; NIDEK, Singapore). The ICP measurements were obtained using a parenchymal sensor (Codman ICP MicroSensor; Johnson & Johnson, Raynham, MA, USA). The pulsatile ICP was determined as ...

      Read Full Article
      Mentions: Nidek
    23. Lateral Resolution of a Commercial Optical Coherence Tomography Instrument

      Lateral Resolution of a Commercial Optical Coherence Tomography Instrument

      Purpose : The lateral resolution of an optical coherence tomography (OCT) instrument was considered to be equal to the illumination spot size on the retina. To evaluate the potential lateral resolution of the Spectralis OCT, an instrument calculated to have a 14 µm resolution. Methods : The lateral point spread function (PSF) was evaluated using diamond abrasive powder 0 to 1 µm in diameter in silicone elastomer and a validated target with 800 nm FeO particles in urethane. The amplitude transfer function was calculated from human OCT images. Finally, resolution was measured using the 1951 USAF target. Results : Measurement of the lateral ...

      Read Full Article
    24. Assessment of Artifacts in Swept-Source Optical Coherence Tomography Angiography for Glaucomatous and Normal Eyes

      Assessment of Artifacts in Swept-Source Optical Coherence Tomography Angiography for Glaucomatous and Normal Eyes

      urpose: To evaluate the frequency of and identify the factors that influence the artifacts of swept-source optical coherence tomography angiography (SS-OCTA) in glaucomatous and normal eyes. Methods: Artifacts of OCTA images of open-angle glaucoma (OAG) and normal subjects were analyzed using SS-OCTA. Univariate and multivariate logistic regression analyses were performed to evaluate the association of age, sex, best-corrected visual acuity, axial length (AL), intraocular pressure, presence and severity of OAG, and image quality score (IQS) with the presence of artifacts. Results: Images from 4426 subjects were included in the study. At least one type of artifact was present in 24 ...

      Read Full Article
    1-24 of 244 1 2 3 4 ... 9 10 11 »
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks