1. Articles from Robert J. Zawadzki

    73-92 of 92 « 1 2 3 4
    1. Optical coherence tomography and Raman spectroscopy of the ex-vivo retina

      Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analysis afforded by Raman scattering could provide critical molecular signatures for clinicians and researchers, there are many technical challenges to combine these imaging modalities. We describe an OCT microscope for ex-vivo imaging combined with Raman spectroscopy capable of collecting morphological and molecular information about a sample simultaneously. We present our first results and discuss the challenges ...
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    2. Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography

      Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography
      Ultrahigh-resolution adaptive optics–optical coherence tomography (UHR-AO-OCT) instrumentation allowing monochromatic and chromatic aberration correction was used for volumetric in vivo retinal imaging of various retinal structures including the macula and optic nerve head (ONH). Novel ... [Opt. Express 17, 4084-4094 (2009)]
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    3. Performance of a MEMS-based AO-OCT system using Fourier reconstruction

      Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution (3.5 µm isotropic), 3-D images of the retina. The AO-OCT system at UC Davis has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses an AOptix bimorph deformable mirror (DM) for low-order, high-stroke correction and a 140-actuator Boston Micromachines DM for high-order correction. Developments to improve performance or functionality of the instrument are on-going. Based on previous work in system characterization we have focused on improved AO control. We present preliminary results and ...
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    4. Optical coherence tomography and Raman spectroscopy of the retina

      Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analy ... [Proc. SPIE 7171, 71710O (2009)] published Fri Feb 20, 2009.
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    5. Comparison of real-time visualization of volumetric OCT data sets by CPU-slicing and GPU-ray casting methods

      We describe and compare two volume visualization methods for Optical Coherence Tomography (OCT) retinal data sets. One of these methods is CPU-slicing, which is previously reported and used in our visualization engine. The other is GPU-ray casting. Several metrics including image quality, performanc ... [Proc. SPIE 7163, 716312 (2009)] published Wed Feb 18, 2009.
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    6. Combined adaptive optics: optical coherence tomography and adaptive optics: scanning laser ophthalmoscopy system for retinal imaging

      We describe a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). Both systems share a common AO sub-system and vertical scanner to permit simultaneous acquisition of retinal images from ... [Proc. SPIE 7163, 71630F (2009)] published Wed Feb 18, 2009.
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    7. Microcystoid Maculopathy Associated With Tamoxifen Use Diagnosed By High-Resolution Fourier-Domain Optical Coherence Tomography.

      Purpose: To describe a case of microcystoid maculopathy diagnosed by high-resolution Fourier-domain optical coherence tomography (Fd-OCT) in a patient treated with tamoxifen who had previously unexplained vision loss. Methods: Report of a case of a 66-year-old woman treated with tamoxifen for 4 years who had progressive unexplained vision loss in the left eye for 2 years. Results: Visual acuity was 20/25 in the right eye and 20/70 in the left eye. Findings of funduscopy and fluorescein angiography were unremarkable except for minimal pigment alteration in the macula in the left eye. Stratus OCT showed possible microcystoid changes in ...
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    8. High-resolution retinal imaging in young children using a handheld scanner and Fourier-domain optical coherence tomography

      Purpose To test the feasibility and applicability of a handheld probe for Fourier-domain optical coherence tomography (Fd-OCT) retinal imaging in infants and children. Methods Thirty children ages 7 months to 9.9 years, with (10 of 30) or without (20 of 30) retinal pathology, were imaged with Fd-OCT. Imaging was performed under sedation in 10 of 30 children ages 7 months to 3.7 years. A high-resolution Fd-OCT system (axial resolution: 4.5 μm; acquisition speeds: 1000 A-scans/frame, 9 frames/second), constructed at the UC Davis Medical Center, in conjunction with a handheld scanner, was used for retinal imaging ...
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    9. Detailed analysis of retinal function and morphology in a patient with autosomal recessive bestrophinopathy (arb)

      Abstract  The objective of the paper is to study the retinal microstructure and function in a patient with autosomal recessive bestrophinopathy (ARB). Retinal function and morphology assessment in a patient diagnosed with a biallelic mutation in the BEST1 gene (heterozygote mutations: Leu88del17 and A195V) included: full-field electroretinogram (ffERG) and multifocal electroretinogram (mfERG), electro-oculogram (EOG) testing, and imaging with a high-resolution Fourier-domain optical coherence tomography (Fd-OCT) system (UC Davis Medical Center; axial resolution: 4.5 μm, acquisition speed: 9 frames/s, 1,000 A-scans/frame) combined with a flexible scanning head (Bioptigen Inc.). The 11-year old asymptomatic boy showed a well-demarcated ...
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    10. High-resolution Fourier-Domain Optical Coherence Tomography and Microperimetric Findings After Macula-off Retinal Detachment Repair

      Objective To evaluate the morphologic changes in the macula of subjects with repaired macula-off retinal detachment (RD) using high-resolution Fourier-domain optical coherence tomography (FD OCT) and to perform functional correlation in a subset of patients using microperimetry (MP-1). Design Prospective observational case series. Participants Seventeen eyes from 17 subjects who had undergone anatomically successful repair for macula-off, rhegmatogenous RD at least 3 months earlier and without visually significant maculopathy on funduscopy. Methods FD OCT with axial and transverse resolution of 4.5 μm and 10 to 15 μm, respectively, was used to obtain rapid serial B-scans of the macula, which ...
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    11. Fourier-Domain Optical Coherence Tomography and Adaptive Optics Reveal Nerve Fiber Layer Loss and Photoreceptor Changes in a Patient With Optic Nerve Drusen.

      June 2008, 28:2 > Fourier-Domain Optical Coherence... ARTICLE LINKS: Fulltext | PDF (822 K) Fourier-Domain Optical Coherence Tomography and Adaptive Optics Reveal Nerve Fiber Layer Loss and Photoreceptor Changes in a Patient With Optic Nerve Drusen. Original Contribution Journal of Neuro-Ophthalmology. 28(2):120-125, June 2008. Choi, Stacey S PhD; Zawadzki, Robert J PhD; Greiner, Mark A MD; Werner, John S PhD; Keltner, John L MD Abstract: Background: New technology allows more precise definit
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    12. Retinal Morphological Changes of Patients With X-linked Retinoschisis Evaluated by Fourier-Domain Optical Coherence Tomography

      Retinal Morphological Changes of Patients With X-linked Retinoschisis Evaluated by Fourier-Domain Optical Coherence Tomography
      Objective  To investigate the retinal microstructure and lamination of patients affected with X-linked retinoschisis (XLRS) using high-resolution imaging modalities. Methods  Patients diagnosed as having XLRS underwent assessment. Visual function testing included visual acuity, color vision, and full-field electroretinography. We used a high-resolution Fourier-domain optical coherence tomography (FD-OCT) system (4.5-µm axial resolution; 9 frames/s; 1000 A-scans per frame) combined with a handheld scanner. Macular image evaluation included schisis localization and retinal layer integrity. Results  Six patients with XLRS and identified mutations in the XLRS1 gene underwent testing. Visual acuity ranged from 0.2 to 1.6 logMAR (logarithm of ...
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    13. Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction

      Robert J. Zawadzki, Barry Cense, Yan Zhang, Stacey S. Choi, Donald T. Miller, John S. Werner. We have developed an improved adaptive optics - optical coherence tomography (AO-OCT) system and evaluated its performance for in vivo imaging of normal and pathologic retina. The instrument provides unprecedented image quality at the retina with isotropic 3D resolution of 3.5 x 3.5 x 3.5 ... [Opt. Express 16, 8126-8143 (2008)]
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    14. Changes in Cellular Structures Revealed by Ultra-high Resolution Retinal Imaging in Optic Neuropathies

      purpose. To study the integrity of inner and outer retinal layers in patients with various types of optic neuropathy by using high-resolution imaging modalities. methods. Three high-resolution imaging systems constructed at the University of California Davis were used to acquire retinal images from patients with optic neuropathy: (1) adaptive optics (AO)-flood–illuminated fundus camera, (2) high-resolution Fourier domain optical coherence tomography (FDOCT), and (3) adaptive optics-Fourier domain optical coherence tomography (AO-FDOCT). The AO fundus camera provides en face images of photoreceptors whereas cross-sectional images (B-scans) of the retina are obtained with both FDOCT and AO-FDOCT. From the volumetric FDOCT ...
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    15. Improved representation of retinal data acquired with volumetric FD-OCT: co-registration, visualization and reconstruction of a large field of view

      Advances in Fourier-domain optical coherence tomography (Fd-OCT) permit visualization of three-dimensional morphology of in-vivo retinal structures in a way that promises to revolutionize clinical and experimental imaging of the retina. The relevance of these advances will be further increased by th ...
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    16. Ultra-high resolution adaptive optics: optical coherence tomography for in vivo imaging of healthy and diseased retinal structures

      Ultra-high isotropic resolution imaging of retinal structures was made possible with an adaptive optics system using dual deformable mirrors and a Fourier-domain optical coherence tomography (Fd-OCT) system with correction for longitudinal chromatic aberration. This system was used to image microsco ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 684408 (2008)] published Mon Feb 11, 2008.
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    17. Performance of a MEMS-based AO-OCT system

      Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution, 3-D images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microsc ... [Proc. SPIE Int. Soc. Opt. Eng. 6888, 68880G (2008)] published Fri Feb 8, 2008.
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    18. Compact MEMS-based adaptive optics: optical coherence tomography for clinical use

      We describe a compact MEMS-based adaptive optics (AO) optical coherence tomography (OCT) system with improved AO performance and ease of clinical use. A typical AO system consists of a Shack-Hartmann wavefront sensor and a deformable mirror that measures and corrects the ocular and system aberrations. Because of limitations on current deformable mirror technologies, the amount of real-time ocular-aberration compensation is restricted and small in previous AO-OCT instruments. In this instrument, we incorporate an optical apparatus to correct the spectacle aberrations of the patients such as myopia, hyperopia and astigmatism. This eliminates the tedious process of using trial lenses in clinical ...
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    19. Simultaneous imaging of human cone mosaic with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography

      M. Pircher, R. J. Zawadzki, J. W. Evans, J. S. Werner, C. K. Hitzenberger We describe a novel instrument capable of acquiring, simultaneously, adaptive optics enhanced scanning laser ophthalmoscopy and optical coherence tomography (OCT) images of the human cone mosaic in vivo. The OCT system is based on transversal scanning of the sample with a line scan rate of 14 kHz, ... [Opt. Lett. 33, 22-24 (2008)]
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    73-92 of 92 « 1 2 3 4
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    1. (91 articles) Robert J. Zawadzki
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