1. Ravi S. Jonnal

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    1. Mentioned In 32 Articles

    2. Kilohertz retinal FF-SS-OCT and flood imaging with hardware-based adaptive optics

      Explore OSA | OSA Publishing Ophthalmology
      Kilohertz retinal FF-SS-OCT and flood imaging with hardware-based adaptive optics
      A retinal imaging system was designed for full-field (FF) swept-source (SS) optical coherence tomography (OCT) with cellular resolution. The system incorporates a real-time adaptive optics (AO) subsystem and a very high-speed CMOS sensor, and is capable of acquiring volumetric images of the retina at rates up to 1 kHz. While digital aberration correction (DAC) is an attractive potential alternative to AO, it has not yet been shown to provide resolution ...
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      Mentions: UC Davis Robert J. Zawadzki Ravi S. Jonnal

    3. Visible light OCT improves imaging through a highly scattering retinal pigment epithelial wall

      Explore OSA | OSA Publishing
      Visible light OCT improves imaging through a highly scattering retinal pigment epithelial wall
      Here we provide a counter-example to the conventional wisdom in biomedical optics that longer wavelengths aid deeper imaging in tissue. Specifically, we investigate visible light optical coherence tomography of Bruchs membrane (BM) in the non-pathologic eyes of humans and two mouse strains. Surprisingly, we find that shorter visible wavelengths improve the visualization of BM in pigmented eyes, where it is located behind a highly scattering layer of melanosomes in the ...
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      Mentions: Vivek J. Srinivasan UC Davis Robert J. Zawadzki

    4. OCT-Based Technique Captures Subtle Details of Photoreceptor Function

      Explore osa.org Ophthalmology
      OCT-Based Technique Captures Subtle Details of Photoreceptor Function
      Researchers have developed a new instrument that has, for the first time, measured tiny light-evoked deformations in individual rods and cones in a living human eye. The new approach could one day improve detection of retinal diseases such as age-related macular degeneration, a leading cause of blindness in people over 55 worldwide. Our instrument offers a unique way to study retinal disease at the cellular level, said research team leader ...
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      Mentions: UC Davis Ravi S. Jonnal

    5. Optoretinogram: optical measurement of human cone and rod photoreceptor responses to light

      Explore OSA | OSA Publishing Ophthalmology
      Optoretinogram: optical measurement of human cone and rod photoreceptor responses to light
      Noninvasive, objective measurement of rod function is as significant as that of cone function, and for retinal diseases such as retinitis pigmentosa and age-related macular degeneration, rod function may be a more sensitive biomarker of disease progression and efficacy of treatment than cone function. Functional imaging of single human rod photoreceptors, however, has proven difficult because their small size and rapid functional response pose challenges for the resolution and speed ...
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      Mentions: John S. Werner UC Davis Robert J. Zawadzki

    7. Automated quantification of choriocapillaris anatomical features in ultrahigh-speed optical coherence tomography angiograms

      Explore OSA | OSA Publishing
      Automated quantification of choriocapillaris anatomical features in ultrahigh-speed optical coherence tomography angiograms
      In vivo visualization and quantification of choriocapillaris vascular anatomy is a fundamental step in understanding the relation between choriocapillaris degradation and atrophic retinopathies, including geographic atrophy. We describe a process utilizing ultrahigh-speed swept-source optical coherence tomography and a custom-designed local min-max normalized masking algorithm to extract in vivo anatomical metrics of the choriocapillaris. We used a swept-source optical coherence tomography system with a 1.6 MHz A-scan rate to image ...
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      Mentions: John S. Werner UC Davis Ravi S. Jonnal

    9. Coextensive synchronized SLO-OCT with adaptive optics for human retinal imaging

      Explore OSA | OSA Publishing Ophthalmology
      Coextensive synchronized SLO-OCT with adaptive optics for human retinal imaging
      We describe the details of a multimodal retinal imaging system which combines adaptive optics (AO) with an integrated scanning light ophthalmoscopy (SLO) and optical coherence tomography (OCT) imaging system. The OCT subsystem consisted of a swept-source, Fourier-domain mode-locked (FDML) laser, with a very high A-scan rate (1.6 MHz), whose beam was raster scanned on the retina by two scannersone resonant scanner and one galvanometer. The high sweep rate of ...
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      Mentions: John S. Werner Robert J. Zawadzki UCSD

    10. ADAPTIVE OPTICS OPHTHALMOSCOPY CONFERENCE SEPTEMBER 4TH, PARIS

      Explore Optical Coherence Tomography News Ophthalmology
      ADAPTIVE OPTICS OPHTHALMOSCOPY CONFERENCE SEPTEMBER 4TH, PARIS
      Late Summer Course - September 4 5, 2019 - Paris High resolution imaging technologies, exemplified by adaptive optics ophthalmoscopy (AOO) and optical coherence tomography (OCT) are progressively transferring from the lab to the clinic. This is an opportunity to better understand retinal diseases, to optimize their management but also to provide novel biomarkers for other medical specialities. However, there is still an unmet need in the field of clinical interpretation of AOO ...
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      Mentions: University of Pittsburgh Michael Pircher Medical University of Vienna

    11. Feature Of The Week 03/01/2019: Functional Retina lmaging using Adaptive Optics Swept-Source OCT at 1.6 MHz

      Explore Optical Coherence Tomography News Ophthalmology
      Feature Of The Week 03/01/2019: Functional Retina lmaging using Adaptive Optics Swept-Source OCT at 1.6 MHz
      Functional assessment of the retina is a critical part of both clinical ophthalmology and vision research. Several techniques exist for measuring retinal function, such as Visual acuity/contrast sensitivity tests, Psychophysics and ERG (Electroretinogram and multifocal Electroretinogram). However, these approaches have important limitations, poor spatial resolution, slightly invasive; long duration of tests. There is great excitement about emerging noninvasive approaches to measuring retinal function, both from clinical and basic scientific ...
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      Mentions: John S. Werner UC Davis Robert J. Zawadzki

    12. Functional retinal imaging using adaptive optics swept-source OCT at 1.6  MHz

      Explore OSA | OSA Publishing
      Functional retinal imaging using adaptive optics swept-source OCT at 1.6  MHz
      Objective optical assessment of photoreceptor function may permit earlier diagnosis of retinal disease than current methods such as perimetry, electrophysiology, and clinical imaging. In this work, we describe an adaptive optics (AO) optical coherence tomography (OCT) system designed to measure functional responses of single cones to visible stimuli. The OCT subsystem consisted of a raster-scanning Fourier-domain mode-locked laser that acquires A scans at 1.64 MHz with a center wavelength ...
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      Mentions: John S. Werner Robert J. Zawadzki UCSD

    13. UC Davis Receives NIH Grant for Studying Properties of Photoreceptors and Muller Cells Investigated with AO-OCT

      Explore Optical Coherence Tomography News Ophthalmology , Funding
      UC Davis Receives NIH Grant for Studying Properties of Photoreceptors and Muller Cells Investigated with AO-OCT
      University of California Davis Receives a 2019 NIH Grant for $245,479 for Properties of Photoreceptors and Muller Cells Investigated with AO-OCT. The principal investigator is Ravi Jonnal. The program began in 2016 and ends in 2020. Below is a summary of the proposed work. The research proposed for this award will examine functional and structural properties of single cells in the human retina. The three Aims will link the ...
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      Mentions: National Institutes of Health John S. Werner UC Davis

    14. Intraframe motion correction for raster-scanned adaptive optics images using strip-based cross-correlation lag biases

      Explore Journals | PLOS Ophthalmology
      Intraframe motion correction for raster-scanned adaptive optics images using strip-based cross-correlation lag biases
      In retinal raster imaging modalities, fixational eye movements manifest as image warp, where the relative positions of the beam and retina change during the acquisition of single frames. To remove warp artifacts, strip-based registration methodsin which fast-axis strips from target images are registered to a reference framehave been applied in adaptive optics (AO) scanning light ophthalmoscopy (SLO) and optical coherence tomography (OCT). This approach has enabled object tracking and frame ...
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      Mentions: Thorlabs Dalsa Superlum

    15. Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz

      Explore bioRxiv.org Ophthalmology
      Functional retinal imaging using adaptive optics swept-source OCT at 1.6MHz
      bjective optical assessment of photoreceptor function may permit earlier diagnosis of retinal disease than current methods such as perimetry, electrophysiology, and clinical imaging. In this work, we describe an adaptive optics (AO) optical coherence tomography (OCT) system designed to measure functional responses of single cones to visible stimuli. The OCT subsystem consisted of a raster-scanning Fourier-domain mode-locked laser that acquires A-scans at 1.64MHz with a center wavelength of 1063nm ...
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      Mentions: John S. Werner Robert J. Zawadzki UCSD

    16. The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography

      Explore IOVS Journal Ophthalmology
      The Properties of Outer Retinal Band Three Investigated With Adaptive-Optics Optical Coherence Tomography
      Purpose : Optical coherence tomography's (OCT) third outer retinal band has been attributed to the zone of interdigitation between RPE cells and cone outer segments. The purpose of this paper is to investigate the structure of this band with adaptive optics (AO)-OCT. Methods : Using AO-OCT, images were obtained from two subjects. Axial structure was characterized by measuring band 3 thickness and separation between bands 2 and 3 in segmented ...
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      Mentions: John S. Werner UC Davis Robert J. Zawadzki
    17. 1-15 of 32 1 2 »
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  4. About Ravi S. Jonnal

    Ravi S. Jonnal

    Ravi S. Jonnal is a project scientist at UC Davis.

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    3. The cellular origins of the outer retinal bands in optical coherence tomography images
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    4. Volumetric retinal imaging with ultrahigh-resolution spectral-domain optical coherence tomography and adaptive optics using two broadband light sources
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