1. Articles from weihua gao

    1-11 of 11
    1. Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics

      Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics
      Early detection of axonal tissue loss in retinal nerve fiber layer (RNFL) is critical for effective treatment and management of diseases such as glaucoma. This study aims to evaluate the capability of ultrahigh-resolution optical coherence tomography with adaptive optics (UHR-AO-OCT) for imaging the RNFL axonal bundles (RNFBs) with 3 × 3 × 3 μm3 resolution in the eye. We used a research-grade UHR-AO-OCT system to acquire 3° × 3° volumes in four normal subjects and one subject with an arcuate retinal nerve fiber layer defect (n = 5; 29–62 years). Cross section (B-scans) and en face (C-scan) slices extracted from the volumes were ...
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    2. Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics

      Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics
      Cone photoreceptors in the living human eye have recently been imaged with micron-scale resolution in all three spatial dimensions using adaptive optics optical coherence tomography. While these advances have allowed non-invasive study of the three-dimensional structure of living human cones, studies of their function and physiology are still hampered by the difficulties to monitor the same cells over time. The purpose of this study is to demonstrate the feasibility of cone monitoring using ultrahigh-resolution adaptive optics optical coherence tomography. Critical to this is incorporation of a high speed CMOS camera (125 KHz) and a novel feature-based, image registration/dewarping algorithm ...
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    3. 3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics

      3D imaging of cone photoreceptors over extended time periods using optical coherence tomography with adaptive optics

      Optical coherence tomography with adaptive optics (AO-OCT) is a highly sensitive, noninvasive method for 3D imaging of the microscopic retina. The purpose of this study is to advance AO-OCT technology by enabling repeated imaging of cone photoreceptors over extended periods of time (days). This sort of longitudinal imaging permits monitoring of 3D cone dynamics in both normal and diseased eyes, in particular the physiological processes of disc renewal and phagocytosis, which are disrupted by retinal diseases such as age related macular degeneration and retinitis pigmentosa. For this study, the existing AO-OCT system at Indiana underwent several major hardware and software ...

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    4. Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics

      Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics
      Purpose: Ultrahigh-resolution optical coherence tomography (UHR-OCT) with adaptive optics (AO) provides micron-scale 3D resolution that is attractive for imaging the retinal microvasculature. Such imaging may be useful for early detection of pathologic changes as in diabetic retinopathy. Here we investigate this potential for detecting individual capillaries in healthy subjects. Methods: UHR-AO-OCT volumes centered on the fovea were acquired from seven subjects (25-61 years) with three pre-selected with no foveal avascular zone (FAZ). Images were compared to entoptic diagrams using the capillaries at the rim of the FAZ. Methods of comparison were: testing for the presence of a FAZ; noting distinct ...
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    5. Directional property of the retinal reflection measured with optical coherence tomography and wavefront sensing (Thesis)

      Directional property of the retinal reflection measured with optical coherence tomography and wavefront sensing (Thesis)
      The last thirty years have experienced tremendous advancement in our understanding of light-tissue interactions in the human retina. Nevertheless, major gaps remain, and our modeling of light return from the back of the eye continues to evolve. The objective of this thesis is to investigate one of these gaps, specifically that related to the directional property (angular dependence) of the retinal reflection and in particular that of cone photoreceptors. Directionality of cones is commonly referred to as the optical Stiles-Crawford effect (SCE). While cone directionality is well known to originate from their waveguide properties, considerable uncertainty remains as to which ...
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    6. Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics

      Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics
      Ultrahigh speed line scan detectors based on CMOS technology have been recently demonstrated in ultrahigh resolution spectral-domain optical coherence tomography (UHR-SD-OCT) for retinal imaging. While successful, fundamental tradeoffs exist been image acquisition time, image sampling density, and sensitivity, all of which impact the extent of motion artifacts, visualization of fine spatial detail, and detection of faint reflections. Here we investigate these tradeoffs for imaging retinal nerve fiber bundles (RNFBs) using UHR-SD-OCT with adaptive optics (AO). Volume scans of 3°x3° and 1.5°x1.5° were acquired at retinal locations of 3° nasal and 6° superior to the fovea on ...
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    7. Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics

      Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics

      Various layers of the retina are well known to alter the polarization state of light. Such changes in polarization may be a sensitive indicator of tissue structure and function, and as such have gained increased clinical attention. Here we demonstrate a polarization-sensitive optical coherence tomography (PS-OCT) system that incorporates adaptive optics (AO) in the sample arm and a single line scan camera in the detection arm. We quantify the benefit of AO for PS-OCT in terms of signal-to-noise, lateral resolution, and speckle size. Double pass phase retardation per unit depth values ranging from 0.25°/μm to 0.65°/μm ...

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    8. Volumetric retinal imaging with ultrahigh-resolution spectral-domain optical coherence tomography and adaptive optics using two broadband light sources

      Volumetric retinal imaging with ultrahigh-resolution spectral-domain optical coherence tomography and adaptive optics using two broadband light sources
      Ultrabroadband sources, such as multiplexed superluminescent diodes (SLDs) and femtosecond lasers, have been successfully employed in adaptive optics optical coherence tomography (AO-OCT) systems for ultrahigh resolution retinal imaging. The large cost differential of these sources, however, motivates the need for a performance comparison. Here, we compare the performance of a Femtolasers Integral Ti:Sapphire laser and a Superlum BroadLighter T840, using the same AO-OCT system and the same subject. In addition, we investigate the capability of our instrument equipped with the Integral to capture volume images of the fovea and adjacent regions on a second subject using the AO to ...
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    9. Does transverse chromatic aberration limit performance of AO-OCT retinal imaging?

      The combination of adaptive optics (AO) and optical coherence tomography (OCT) has been successfully applied to in vivo retinal imaging, motivated by the potential of unprecedented 3D resolution. The eye, however, not only suffers from monochromatic aberrations, which are corrected by AO, but also s ... [Proc. SPIE 7139, 71390Z (2008)] published Tue Dec 30, 2008.
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    10. Measuring retinal contributions to the optical Stiles-Crawford effect with optical coherence tomography

      The directional component of the retinal reflection, i.e., the optical Stiles-Crawford effect (SCE), is well established to result from the waveguiding property of photoreceptors. Considerable uncertainty, however, remains as to which retinal reflections are waveguided and thus contribute. To this ... [Opt. Express 16, 6486-6501 (2008)]
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    11. In vivo functional imaging of humancone photoreceptors

      We evaluate a novel non-invasive optical technique for observing fast physiological processes, in particular phototransduction, in single photoreceptor cells in the living human eye. The method takes advantage of the interference of multiple reflections within the outer segments (OS) of cones. ... [Opt. Express 15, 16141-16160 (2007)]

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    1-11 of 11
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  2. Topics in the News

    1. (11 articles) Indiana University
    2. (11 articles) Weihua Gao
    3. (11 articles) Donald T. Miller
    4. (8 articles) Barry Cense
    5. (8 articles) Ravi S. Jonnal
    6. (6 articles) Omer P. Kocaoglu
    7. (5 articles) Qiang Wang
    8. (1 articles) Jungtae Rha
    9. (1 articles) Johannes F. de Boer
    10. (1 articles) Basler
    11. (1 articles) University of Washington
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    Volumetric retinal imaging with ultrahigh-resolution spectral-domain optical coherence tomography and adaptive optics using two broadband light sources Retinal imaging with polarization-sensitive optical coherence tomography and adaptive optics Imaging retinal nerve fiber bundles at ultrahigh-speed and ultrahigh-resolution using OCT with adaptive optics Imaging Retinal Capillaries Using Ultrahigh-Resolution Optical Coherence Tomography and Adaptive Optics Imaging cone photoreceptors in three dimensions and in time using ultrahigh resolution optical coherence tomography with adaptive optics Imaging retinal nerve fiber bundles using optical coherence tomography with adaptive optics Directional property of the retinal reflection measured with optical coherence tomography and wavefront sensing (Thesis) Optical microangiography reveals temporal and depth-resolved hemodynamic change in mouse barrel cortex during whisker stimulation Optical coherence tomography for fast bedside imaging, assessment and monitoring of autoimmune inflammatory skin diseases? Monitoring fatigue damage in different CAD/CAM materials: A new approach with optical coherence tomography. Automatic diagnosis of macular diseases from OCT volume based on its two-dimensional feature map and convolutional neural network with attention mechanism. Characteristics of the Filtering Bleb and the Agreement between Glaucoma Specialist and Anterior Segment OCT Assessment.