1. Articles from Antoine Ramier

    1-5 of 5
    1. Ultrahigh resolution spectral-domain optical coherence tomography using the 1000-1600 nm spectral band

      Ultrahigh resolution spectral-domain optical coherence tomography using the 1000-1600 nm spectral band

      Ultrahigh resolution optical coherence tomography (UHR-OCT) can image microscopic features that are not visible with the standard OCT resolution of 5-15 µm. In previous studies, high-speed UHR-OCT has been accomplished within the visible (VIS) and near-infrared (NIR-I) spectral ranges, specifically within 550-950 nm. Here, we present a spectral domain UHR-OCT system operating in a short-wavelength infrared (SWIR) range from 1000 to 1600 nm using a supercontinuum light source and an InGaAs-based spectrometer. We obtained an axial resolution of 2.6 µm in air, the highest ever recorded in the SWIR window to our knowledge, with deeper penetration into tissues than ...

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    2. Optical coherence tomographic measurements of the sound-induced motion of the ossicular chain in chinchillas: Additional modes of ossicular motion enhance the mechanical response of the chinchilla middle ear at higher frequencies

      Optical coherence tomographic measurements of the sound-induced motion of the ossicular chain in chinchillas: Additional modes of ossicular motion enhance the mechanical response of the chinchilla middle ear at higher frequencies

      Wavelength-swept optical coherence tomography (OCT) was used to scan the structure of cadaveric chinchilla ears in three dimensions with high spatial resolution and measure the sound-induced displacements of the entire OCT-visible lateral surfaces of the ossicles in the lateral-to-medial direction. The simultaneous measurement of structure and displacement allowed a precise match between the observed motion and its structural origin. The structure and measured displacements are consistent with previously published data. The coincident detailed structural and motion measurements demonstrate the presence of several frequency-dependent modes of ossicular motion, including: (i) rotation about an anteriorly-to-posteriorly directed axis positioned near the commonly defined ...

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    3. 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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    4. Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography

      Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography

      The sound-driven vibration of the tympanic membrane and ossicular chain of middle-ear bones is fundamental to hearing. Here we show that optical coherence tomography in phase synchrony with a sound stimulus is well suited for volumetric, vibrational imaging of the ossicles and tympanic membrane. This imaging tool — OCT vibrography — provides intuitive motion pictures of the ossicular chain and how they vary with frequency. Using the chinchilla ear as a model, we investigated the vibrational snapshots and phase delays of the manubrium, incus, and stapes over 100 Hz to 15 kHz. The vibrography images reveal a previously undescribed mode of motion ...

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    5. Observation of sound-induced corneal vibrational modes by optical coherence tomography

      Observation of sound-induced corneal vibrational modes by optical coherence tomography

      The mechanical stability of the cornea is critical for maintaining its normal shape and refractive function. Here, we report an observation of the mechanical resonance modes of the cornea excited by sound waves and detected by using phase-sensitive optical coherence tomography. The cornea in bovine eye globes exhibited three resonance modes in a frequency range of 50-400 Hz. The vibration amplitude of the fundamental mode at 80-120 Hz was ~8 µm at a sound pressure level of 100 dB (2 Pa). Vibrography allows the visualization of the radially symmetric profiles of the resonance modes. A dynamic finite-element analysis supports our ...

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    1-5 of 5
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  2. Topics in the News

    1. (5 articles) Harvard University
    2. (3 articles) Massachusetts General Hospital
    3. (2 articles) Massachusetts Eye and Ear Infirmary
    4. (1 articles) Tsinghua University
    5. (1 articles) Spanish National Research Council
    6. (1 articles) University of Maryland
    7. (1 articles) Massachusetts Institute of Technology
    8. (1 articles) University of Bologna
    9. (1 articles) University of Cambridge
    10. (1 articles) FDA
    11. (1 articles) Notal Vision
    12. (1 articles) Topcon Medical Systems
    13. (1 articles) Tomey Corporation
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    Observation of sound-induced corneal vibrational modes by optical coherence tomography Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography Measuring mechanical wave speed, dispersion, and viscoelastic modulus of the cornea using optical coherence elastography Optical coherence tomographic measurements of the sound-induced motion of the ossicular chain in chinchillas: Additional modes of ossicular motion enhance the mechanical response of the chinchilla middle ear at higher frequencies Ultrahigh resolution spectral-domain optical coherence tomography using the 1000-1600 nm spectral band Comparison of Anterior Segment Measurements with a New Multifunctional Unit and Five Other Devices Efficacy of Notal Vision Home OCT demonstrated by a series of scientific and clinical work Synergy Between morpHOlogical and inflammatoRy Evaluation in Predicting Long-term Coronary Plaque Progression Altered ocular microvasculature in patients with systemic sclerosis and very early disease of systemic sclerosis using optical coherence tomography angiography Assessment of macular findings by OCT angiography in patients without clinical signs of diabetic retinopathy: radiomics features for early screening of diabetic retinopathy Self-Examination Low-Cost Full-Field Optical Coherence Tomography (SELFF-OCT) for neovascular age-related macular degeneration: a cross-sectional diagnostic accuracy study The Use of Optical Coherence Tomography to Demonstrate Dark and Light Adaptation in a Live Moth