1. Articles from Jun Zhu

    1-7 of 7
    1. Visibility of microvessels in Optical Coherence Tomography Angiography depends on angular orientation

      Visibility of microvessels in Optical Coherence Tomography Angiography depends on angular orientation

      OCT Angiography (OCTA) is a widespread tool for depth‐resolved imaging of chorioretinal vasculature with single microvessel resolution. To improve the clinical interpretation of OCTA, the conditions affecting visualization of microvessels must be defined. Here we inject a scattering plasma tracer (Intralipid) during OCTA imaging of the anesthetized rat eye. In the retina, we find that interlaminar (vertical) vessels that connect laminae have one‐fourth to one‐third the OCTA red blood cell to tracer (RBC‐to‐tracer) signal ratio of intralaminar (horizontal) vessels. This finding suggests that the OCTA signal from microvessels depends on angular orientation, making vertically‐oriented ...

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    2. Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns

      Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns

      n biological tissue, longer near-infrared wavelengths generally experience less scattering and more water absorption. Here we demonstrate an optical coherence tomography (OCT) system centered at 2.1 microns, whose bandwidth falls in the 2.2 micron water absorption optical window, for in vivo imaging of the rodent brain. We show in vivo that at 2.1 microns, the OCT signal is actually attenuated less in cranial bone than at 1.3 microns, and is also less susceptible to multiple scattering tails. We also show that the 2.2 micron window enables direct spectroscopic OCT assessment of tissue water content. We ...

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    3. Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo

      Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo

      Studies of flow-metabolism coupling often presume that microvessel architecture is a surrogate for blood flow. To test this assumption, we introduce an in vivo Dynamic Contrast Optical Coherence Tomography (DyC-OCT) method to quantify layer-resolved microvascular blood flow and volume across the full depth of the mouse neocortex, where the angioarchitecture has been previously described . First, we cross-validate average DyC-OCT cortical flow against conventional Doppler OCT flow. Next, with laminar DyC-OCT, we discover that layer 4 consistently exhibits the highest microvascular blood flow, approximately two-fold higher than the outer cortical layers. While flow differences between layers are well-explained by microvascular volume ...

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    4. Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

      Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution

      Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency in scattering tissue. This was achieved by overfilling a 0.3 numerical aperture (NA) water immersion objective on the illumination path, while maintaining a conventional Gaussian mode detection path (1/e 2 intensity diameter ~0.82 Airy disks), enabling ~1.1 ...

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    5. Visible Light Optical Coherence Microscopy of the Brain with Isotropic Femtoliter Resolution In Vivo

      Visible Light Optical Coherence Microscopy of the Brain with Isotropic Femtoliter Resolution In Vivo

      Most flying-spot Optical Coherence Tomography (OCT) and Optical Coherence Microscopy (OCM) systems use a symmetric confocal geometry, where the detection path retraces the illumination path starting from and ending with the spatial mode of a single mode optical fiber. Here, we describe a visible light OCM instrument that breaks this symmetry to improve transverse resolution without sacrificing collection efficiency. This was achieved by overfilling a water immersion objective on the illumination path, while maintaining a conventional Gaussian mode detection path (1/e2 intensity diameter ~0.82 Airy disks), enabling ~1.1 μm full-width at half-maximum (FWHM) transverse resolution. At the ...

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    6. Can OCT Angiography Be Made a Quantitative Blood Measurement Tool?

      Can OCT Angiography Be Made a Quantitative Blood Measurement Tool?

      Optical Coherence Tomography Angiography (OCTA) refers to a powerful class of OCT scanning protocols and algorithms that selectively enhance the imaging of blood vessel lumens, based mainly on the motion and scattering of red blood cells (RBCs). Though OCTA is widely used in clinical and basic science applications for visualization of perfused blood vessels, OCTA is still primarily a qualitative tool. However, more quantitative hemodynamic information would better delineate disease mechanisms, and potentially improve the sensitivity for detecting early stages of disease. Here, we take a broader view of OCTA in the context of microvascular hemodynamics and light scattering. Paying ...

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    7. Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

      Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery

      AIM : To investigate the effect of simulated dynamic intraocular pressure (SDIOP) during uncomplicated phacoemulsification on postoperative macular and peripapillary retinal nerve fiber layer (RNFL) thickness. METHODS : Macular and RNFL thicknesses in one eye of patients (n=30) undergoing uncomplicated phacoemulsification were measured by optical coherence tomography preoperatively and 1 week postoperatively. The best-corrected visual acuity, SDIOP, irrigation time (IT), effective phacoemulsification time, entire surgical duration, blood pressure, and heart rate were recorded. RESULTS : The mean SDIOP and IT was (74.9 ± 27.4)cmH2O and (178.4 ± 21.6) seconds respectively. We divided our patients into two groups based upon ...

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    1-7 of 7
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    1. (6 articles) UC Davis
    2. (6 articles) Vivek J. Srinivasan
    3. (2 articles) Cornell University
    4. (2 articles) Stanford University
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    Effect of simulated dynamic intraocular pressure on retinal thickness measured by optical coherence tomography after cataract surgery Can OCT Angiography Be Made a Quantitative Blood Measurement Tool? Visible Light Optical Coherence Microscopy of the Brain with Isotropic Femtoliter Resolution In Vivo Visible light optical coherence microscopy imaging of the mouse cortex with femtoliter volume resolution Dynamic Contrast Optical Coherence Tomography reveals laminar microvascular hemodynamics in the mouse neocortex in vivo Noninvasive, in vivo rodent brain optical coherence tomography at 2.1  microns Visibility of microvessels in Optical Coherence Tomography Angiography depends on angular orientation Progression of Photoreceptor Degeneration in Geographic Atrophy Secondary to Age-related Macular Degeneration The interplay of organ-of-Corti vibrational modes, not tectorial- membrane resonance, sets outer-hair-cell stereocilia phase to produce cochlear amplification Comparison of Optical Low-Coherence Reflectometry and Swept-Source OCT–Based Biometry Devices in Dense Cataracts In vivo characterisation of healthy human skin with a novel, non‐invasive imaging technique: line‐field confocal optical coherence tomography Heritability of macular ganglion cell inner plexiform layer thickness as determined by optical coherence tomography: the Healthy Twin Study