1. Articles from Sepideh Hariri

    1-16 of 16
    1. Anterior segment optical coherence tomography evaluation of ocular graft-versus-host disease: a case study

      Anterior segment optical coherence tomography evaluation of ocular graft-versus-host disease: a case study

      To explore ocular graft-versus-host disease (GVHD), anterior segment optical coherence tomography (AS-OCT) imaging of eyelids, tear meniscus, cornea and conjunctiva is performed in subsequent sessions on a patient who has ocular GVHD after allogeneic related donor stem cell transplant. The OCT results are presented together with those from a normal subject. OCT imaging is promising in visualizing several ocular GVHD manifestations, such as abnormal meibomian gland orifice (MGO), conjunctival keratinization, conjunctival hyperemia and chemosis, corneal epithelium opacification, thinning and sloughing. This case study demonstrates the capability of AS-OCT in the imaging and monitoring of ocular GVHD, which may be useful ...

      Read Full Article
    2. Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

      The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the ...

      Read Full Article
    3. Noninvasive imaging of the early effect of sodium iodate toxicity in a rat model of outer retina degeneration with spectral domain optical coherence tomography

      Noninvasive imaging of the early effect of sodium iodate toxicity in a rat model of outer retina degeneration with spectral domain optical coherence tomography

      An ultrahigh resolution spectral domain optical coherence tomography (SD-OCT) system is used to observe for the first time in vivo the early effect of sodium iodate ( NaIO 3 ) toxicity on retinal morphology. Retinal degeneration is induced in rats via tail vein injection of NaIO 3 and structural changes in the outer retina are assessed longitudinally at baseline and 1, 2, 3, 6, 8, and 10 h, and 12 post drug administration with OCT, H&E histology, and IgG immunochemistry. Disruption of the structural integrity and changes in the optical reflectivity of the photoreceptor inner (IS) and outer segment (OS) layers ...

      Read Full Article
    4. Stimulus-Specific Pupil Dynamics Measured in Birds (Gallus gallus domesticus) In Vivo with Ultrahigh Resolution Optical Coherence Tomography

      Stimulus-Specific Pupil Dynamics Measured in Birds (Gallus gallus domesticus) In Vivo with Ultrahigh Resolution Optical Coherence Tomography
      Purpose. To demonstrate the ability of high speed, ultrahigh-resolution optical coherence tomography (UHR-OCT) to measure and characterize in vivo visual stimulus-specific pupil dynamics in birds. Methods. Ten two-week old White Leghorn ( Gallus gallus domesticus ) chickens were imaged in this study. The chickens were dark-adapted for 1 hour and anesthetized with 2% isoflurane prior to the imaging procedure. Blue, green, and red single flash visual stimuli of 7 ms duration were used to evoke pupillary responses. UHR-OCT cross-sectional images of the pupil were acquired prior, during, and for several seconds after the visual stimuli onset. Images were processed with a novel ...
      Read Full Article
    5. Stimulus Specific Pupil Dynamics Measured in Birds (Gallus Gallus Domesticus) in vivo with Ultrahigh Resolution Optical Coherence Tomography

      Stimulus Specific Pupil Dynamics Measured in Birds (Gallus Gallus Domesticus) in vivo with Ultrahigh Resolution Optical Coherence Tomography

      Purpose:To demonstrate the ability of high speed, ultra-high resolution optical coherence tomography (UHR-OCT) to measure and characterize in vivo visual stimulus specific pupil dynamics in birds. Methods:Ten two-week old White Leghorn (Gallus gallus domesticus) chickens were imaged in this study. The chickens were dark adapted for one hour and anesthetized with 2% isoflurane prior to the imaging procedure. Blue, green, and red single flash visual stimuli of 7ms duration were used to evoke pupillary responses. UHR-OCT cross-sectional images of the pupil were acquired prior, during and for several seconds after the visual stimuli onset. Images were processed with ...

      Read Full Article
    6. In vivo Assessment of Thickness and Reflectivity in a Rat Outer Retinal Degeneration Model with Ultrahigh Resolution Optical Coherence Tomography

      In vivo Assessment of Thickness and Reflectivity in a Rat Outer Retinal Degeneration Model with Ultrahigh Resolution Optical Coherence Tomography

      Purpose: To provide in vivo quantitative assessment of sodium iodate-induced retinal damage in a rat model of outer retina degeneration using ultrahigh resolution optical coherence tomography (UHR-OCT). Methods: Outer retinal degeneration was induced in 4 female Long Evans rats via tail vein injection of sodium iodate (40 mg/kg). Changes in the thickness and optical reflectivity of individual retinal layers were extracted using a semi-automatic segmentation algorithm and were assessed in vivo at 6 hours, days 1, 3 and 7 and up to 3 months post-injection with UHR-OCT. H & E histology was used to confirm the morphological changes observed in ...

      Read Full Article
    7. Correlation of visually evoked intrinsic optical signals and electroretinograms recorded from chicken retina with a combined functional optical coherence tomography and electroretinography system

      Correlation of visually evoked intrinsic optical signals and electroretinograms recorded from chicken retina with a combined functional optical coherence tomography and electroretinography system

      Visually evoked fast intrinsic optical signals (IOSs) were recorded for the first time in vivo from all layers of healthy chicken retina by using a combined functional optical coherence tomography (fOCT) and electroretinography (ERG) system. The fast IOSs were observed to develop within ∼ 5  ms from the on-set of the visual stimulus, whereas slow IOSs were measured up to 1 s later. The visually evoked IOSs and ERG traces were recorded simultaneously, and a clear correlation was observed between them. The ability to measure visually evoked fast IOSs non-invasively and in vivo from individual retinal layers could significantly improve the ...

      Read Full Article
    8. Tensor total variation approach to optical coherence tomography reconstruction for improved visualization of retinal microvasculature

      Tensor total variation approach to optical coherence tomography reconstruction for improved visualization of retinal microvasculature

      A novel optical coherence tomography (OCT) reconstruction approach is introduced for improved visualization of inner-retina capillaries in retinal OCT tomograms. The proposed method utilizes a minimization framework based on a tensor total variation (TTV) energy functional, to enforce capillary structural characteristics in the spatial domain. By accounting for structure tensor characteristics, the TTV reconstruction method allows for contrast enhancement of capillary structural characteristics. The novel TTV method was tested on high resolution OCT images acquired in-vivo from the foveal region of the retina of a healthy human subject. Experimental results demonstrate significant contrast and visibility enhancement of the inner retina ...

      Read Full Article
    9. In vivo imaging of intrinsic optical signals in chicken retina with functional optical coherence tomography

      In vivo imaging of intrinsic optical signals in chicken retina with functional optical coherence tomography

      Visually evoked intrinsic optical signals (IOSs) were measured in vivo for the first time to our knowledge from all retina layers of the chicken retina with a combined functional optical coherence tomography and electroretinography (ERG) system. IOS traces were recorded from a small volume in the retina with 3.5 μm axial resolution and 7 ms time resolution. Comparison of the IOS and ERG traces shows a correlation between the positive and negative IOS measured from different retinal layers and the timing of the a and b waves in the ERG recording.

      Read Full Article
    10. In vivo volumetric imaging of chicken retina with ultrahigh-resolution spectral domain optical coherence tomography

      In vivo volumetric imaging of chicken retina with ultrahigh-resolution spectral domain optical coherence tomography

      The chicken retina is an established animal model for myopia and light-associated growth studies. It has a unique morphology: it is afoveate and avascular; oxygen and nutrition to the inner retina is delivered by a vascular tissue (pecten) that protrudes into the vitreous. Here we present, to the best of our knowledge, the first in vivo, volumetric high-resolution images of the chicken retina. Images were acquired with an ultrahigh-resolution optical coherence tomography (UHROCT) system with 3.5 µm axial resolution in the retina, at the rate of 47,000 A-scans/s. Spatial variations in the thickness of the nerve fiber ...

      Read Full Article
    11. In-vivo human retina imaging with 5μm axial resolution, at 92000 A-scans/s with 1μm spectral domain OCT system

      In-vivo human retina imaging with 5μm axial resolution, at 92000 A-scans/s with 1μm spectral domain OCT system

      We have outfitted a 1060nm Spectral Domain Optical Coherence Tomography system with a prototype, high speed infrared linear array camera and a custom spectrally reshaped superluminescent diode to achieve 5μm axial resolution at 91,911 A-scans/s image acquisition rate in-vivo in the human retina. 4dB loss of sensitivity was observed as a result of the reduced integration time (7μs) of the fast camera as compared to similar commercially available cameras with 14μs integration time and 47kHz readout rate. Fewer motion artefacts were observed in the retinal images acquired with the fast camera, while the higher axial resolution along with ...

      Read Full Article
    12. Combined optical coherence tomography and electroretinography system for in vivo simultaneous morphological and functional imaging of the rodent retina

      Combined optical coherence tomography and electroretinography system for in vivo simultaneous morphological and functional imaging of the rodent retina

      A combined ultrahigh resolution optical coherence tomography (UHROCT) and a electroretinography (ERG) system is presented for simultaneous imaging of the retinal structure and physiological response to light stimulation in the rodent eye. The 1060-nm UHROCT system provides ~3×5 µm (axial×lateral) resolution in the rat retina and time resolution of 22 µs. A custom-designed light stimulator integrated into the UHROCT imaging probe provides light stimuli with user-selected color, duration, and intensity. The performance of the combined system is demonstrated in vivo in healthy rats, and in a rat model of drug-induced outer retinal degeneration. Experimental results show correlation between ...

      Read Full Article
    13. Swelling of the Human Cornea Revealed by High Speed, Ultrahigh Resolution Optical Coherence Tomography

      Swelling of the Human Cornea Revealed by High Speed, Ultrahigh Resolution Optical Coherence Tomography

      Purpose: To evaluate the change in thickness of the anterior, stromal and posterior corneal laminae in response to hypoxia induced corneal swelling using ultra-high resolution optical coherence tomography (UHR-OCT). Methods: An UHR-OCT system, operating in the 1060nm range, was used to acquire in vivo cross-sectional images of human cornea with 3.2µm x 10µm (axial x lateral) resolution in corneal tissue. Corneal edema was induced by inserting a thick, positive powered soft contact lens over which the eye was closed and patched for 3 hours. Tomograms were acquired from 8 non-contact lens wearers. Baseline images were obtained prior ...

      Read Full Article
    14. Limiting factors to the OCT axial resolution
for in-vivo imaging of human and rodent retina in the 1060nm wavelength range

      Limiting factors to the OCT axial resolution
for in-vivo imaging of human and rodent retina in the 1060nm wavelength range

      A computational model was developed to evaluate the limitations to the highest axial resolution, achievable with ultrahigh resolution optical coherence tomography (UHROCT) in the 1060nm wavelength region for in-vivo imaging of the human and rodent retina. The model considers parameters such as the wavelength dependent water absorption, the average length of the human and rodent eyes, and the power limitations for the imaging beam as defined in the ANSI standard. A custom-built light source with re-shaped spectrum was used to verify experimentally the results from the computational model. Axial OCT resolution of 4.2µm and 7.7µm was ...

      Read Full Article
    15. The broadest spectral bandwidth suitable for in-vivo UHROCT imaging of human and animal retina at 1060nm

      A computational model for an "ideal" light source for in-vivo UHROCT imaging of human and animal retina is presented. The model considers parameters such as the wavelength dependent absorption of water, the length of the human or animal eye, the power limitations for the imaging beam as defined in the ANSI standard, etc., to determinethe broadest possible spectral bandwidth that can result in the best axial OCT resolution in the 1060nm wavelength region. A custom light source with a re-shaped spectrum was used to verify experimentally the results from the computational model. 4.3m axial OCT resolution was achieved experimentally ...

      Read Full Article
    16. Evaluation of hypoxic swelling of human cornea with high speed, ultrahigh resolution optical coherence tomography

      Hypoxia induced corneal swelling was observed and evaluated in healthy human volunteers by use of high speed, ultrahigh resolution optical coherence tomography (UHROCT). Two dimensional corneal images were acquired at a speed of 47,000 A-scans/s with 3m x 10m (axial x lateral) resolution in corneal tissue. The UHROCT tomograms showed clear visualization of all corneal layers, including the Bowman's layer and the Descemet's membrane - Endothelium complex. A segmentation algorithm was developed and used for automatic detection of the boundaries of the different corneal layers and evaluation the individual layer thickness as a function of location. Corneal ...

      Read Full Article
    1-16 of 16
  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
  2. Topics in the News

    1. (16 articles) Sepideh Hariri
    2. (14 articles) University of Waterloo
    3. (14 articles) Kostadinka K. Bizheva
    4. (11 articles) Alireza A. Moayed
    5. (3 articles) University of Toronto
    6. (2 articles) University of Washington
    7. (2 articles) Ruikang K. Wang
    8. (2 articles) Natalie Hutchings
    9. (2 articles) Massachusetts General Hospital
    10. (1 articles) Luigina Sorbara
    11. (1 articles) Superlum
    12. (1 articles) Harvard University
    13. (1 articles) The Chinese University of Hong Kong
    14. (1 articles) University of Miami
    15. (1 articles) VU University Amsterdam
    16. (1 articles) David A. Boas
    17. (1 articles) Brett E. Bouma
    18. (1 articles) Johannes F. de Boer
    19. (1 articles) Frank D. Verbraak
    20. (1 articles) Apollo Medical Optics
  3. Popular Articles

  4. Picture Gallery

    Limiting factors to the OCT axial resolution
for in-vivo imaging of human and rodent retina in the 1060nm wavelength range Swelling of the Human Cornea Revealed by High Speed, Ultrahigh Resolution Optical Coherence Tomography Combined optical coherence tomography and electroretinography system for in vivo simultaneous morphological and functional imaging of the rodent retina In-vivo human retina imaging with 5μm axial resolution, at 92000 A-scans/s with 1μm spectral domain OCT system In vivo volumetric imaging of chicken retina with ultrahigh-resolution spectral domain optical coherence tomography In vivo imaging of intrinsic optical signals in chicken retina with functional optical coherence tomography Tensor total variation approach to optical coherence tomography reconstruction for improved visualization of retinal microvasculature Noninvasive imaging of the early effect of sodium iodate toxicity in a rat model of outer retina degeneration with spectral domain optical coherence tomography Optical Coherence Tomography: Critical Tool to Manage Expectations after Cataract Extraction Improving the characterization of ex vivo human brain optical properties using high numerical aperture optical coherence tomography by spatially constraining the confocal parameters Choroidal, macular and ganglion cell layer thickness assessment in Caucasian children measured with spectral domain optical coherence tomography Examination of retinal vascular density changes via optical coherence tomography angiography in patients with glaucoma