1. Articles from Alireza Akhlagh Moayed

    1-10 of 10
    1. Automatic tracking of pupillary dynamics from in vivo functional optical coherence tomography images

      Automatic tracking of pupillary dynamics from in vivo functional optical coherence tomography images

      A major challenge currently faced in measuring visually evoked optical changes in different retinal layers using in vivo and non-invasive functional optical coherence tomography (fOCT) is the need for pupillary dilation drugs to enable reliable measurement of the retinal functional responses. However, there are situations where the use of pupillary dilation drugs is not suitable in both clinical and animal ophthalmic research situations. To overcome this challenge, we propose a new approach to tracking visually evoked pupillary dynamics, based on the use of a fast scanning fOCT system and a novel computerised framework, which can then be used to isolate ...

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    2. 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 ...

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    3. 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 ...
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    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, 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 ...

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    5. 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 ...

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    6. 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 ...

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    7. 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.

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    8. 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 ...

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    9. 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 ...

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    10. Modelling the optical response of human retinal photoreceptors to plane wave illumination with the finite integration technique

      The early stages of ocular diseases such as Diabetic Retinopathy are manifested by morphological changes in retinal tissue occurring on cellular level. Therefore, a number of ophthalmic diseases can be diagnosed at an early stage by detecting spatial and temporal variations in the scattering profile ... [Proc. SPIE 7168, 71680H (2009)] published Tue Feb 24, 2009.
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    1-10 of 10
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    1. (10 articles) University of Waterloo
    2. (10 articles) Kostadinka K. Bizheva
    3. (9 articles) Alireza A. Moayed
    4. (8 articles) Sepideh Hariri
    5. (1 articles) University of Toronto
    6. (1 articles) Medical University of Vienna
    7. (1 articles) Harbin Medical University
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    Combined optical coherence tomography and electroretinography system for in vivo simultaneous morphological and functional imaging of the rodent retina 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 Correlation of visually evoked intrinsic optical signals and electroretinograms recorded from chicken retina with a combined functional optical coherence tomography and electroretinography system In vivo Assessment of Thickness and Reflectivity in a Rat Outer Retinal Degeneration Model with Ultrahigh Resolution Optical Coherence Tomography 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 Noninvasive imaging of the early effect of sodium iodate toxicity in a rat model of outer retina degeneration with spectral domain optical coherence tomography Automatic tracking of pupillary dynamics from in vivo functional optical coherence tomography images Changes in the Retinal Microvasculature Measured Using Optical Coherence Tomography Angiography According to Age Direct en-face, speckle-reduced images using angular-compounded Master-Slave optical coherence tomography A case report of a recurrent early and late Bioresorbable vascular scaffold thrombosis: serial angiography and optical coherence tomography findings