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Articles from Robert J. Zawadzki

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  1. Retinal imaging with a combined adaptive optics/optical coherence tomography and adaptive optics/scanning laser ophthalmoscopy system

    Explore Article SPIE Digital Library (Mar 2 2010) Ophthalmology

    Retinal imaging with a combined adaptive optics/optical coherence tomography and adaptive optics/scanning laser ophthalmoscopy system We describe results of retinal imaging with a novel instrument that combines adaptive optics - Fourier-domain optical coherence tomography (AO-OCT) with an adaptive optics scanning laser ophthalmoscope (AO-SLO). One of the benefits of combining Fd-OCT with SLO includes automatic co-registration between the two imaging modalities and the potential for correcting lateral and transversal eye motion resulting in motion artifact-free volumetric retinal imaging. Additionally this allows for direct comparison between retinal structures that can be imaged with both modalities (e.g., photoreceptor mosaics or microvasculature maps). This dual imaging modality could provide insight into some retinal properties that could not be accessed ... (Read Full Article)

    Comment on Article Mentions:   UC Davis   Robert J. Zawadzki   Lawrence Livermore National Laboratory

  2. Evaluation of complex conjugate artifact removal methods used in spectrometer-based Fourier-domain optical coherence tomography systems - a comparative study

    Explore Article SPIE Digital Library (Feb 19 2010)

    Evaluation of complex conjugate artifact removal methods used in spectrometer-based Fourier-domain optical coherence tomography systems - a comparative study We evaluated several, previously published, complex conjugate artifact removal methods and algorithms that have been proposed for Fourier domain optical coherence tomography (Fd-OCT). To ensure comparable conditions, only one OCT system was used, but with modified data acquisition schemes, depending on the requirements of each method/algorithm. This limited our evaluation to single spectrometer based Fd-OCT approaches. The suppression ratio of complex conjugate artifact images using a paperboard is assessed for all tested methods. Several other metrics are also used for comparison, including a list of additional hardware requirements (beyond standard Fd-OCT components) and data acquisition schemes. Finally, in vivo human ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   UC Davis

  3. Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique

    Explore Article opticsinfobase.org (Nov 19 2009) Ophthalmology

    Volumetric microvascular imaging of human retina using optical coherence tomography with a novel motion contrast technique Phase variance-based motion contrast imaging is demonstrated using a spectral domain optical coherence tomography system for the in vivo human retina. This contrast technique spatially identifies locations of motion within the retina primarily associated with vasculature. Histogrambased noise analysis of the motion contrast images was used to reduce the motion noise created by transverse eye motion. En face summation images created from the 3D motion contrast data are presented with segmentation of selected retinal layers to provide non-invasive vascular visualization comparable to currently used invasive angiographic imaging. This motion contrast technique has demonstrated the ability to visualize resolutionlimited vasculature independent ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Scott E. Fraser   Robert J. Zawadzki

  4. Error Budget Analysis for an Adaptive Optics Optical Coherence Tomography System

    Explore Article opticsinfobase.org (Jul 24 2009) Ophthalmology

    Error Budget Analysis for an Adaptive Optics Optical Coherence Tomography System The combination of adaptive optics (AO) technology with optical coherence tomography (OCT) instrumentation for imaging the retina has proven to be a valuable tool for clinicians and researchers in understanding the healthy and diseased eye. The micrometer-isotropic resolution achieved by such a system allows imaging of the retina at a cellular level, however imaging of some cell types remains elusive. Improvement in contrast rather than resolution is needed and can be achieved through better AO correction of wavefront aberration. A common tool for assessing and ultimately improving AO system performance is the development of an error budget. Specifically, this is ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Scot S. Olivier   Steven M. Jones

  5. Optical coherence tomography and Raman spectroscopy of the ex-vivo retina

    Explore Article www3.interscience.wiley.com (Jun 30 2009) Ophthalmology

    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 ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   UC Davis   Robert J. Zawadzki

  6. Cellular resolution volumetric in vivo retinal imaging with adaptive optics–optical coherence tomography

    Explore Article opticsinfobase.org (Mar 2 2009) Ophthalmology

    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)] (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   Julia W. Evans

  7. Performance of a MEMS-based AO-OCT system using Fourier reconstruction

    Explore Article SPIE Digital Library (Feb 23 2009) Ophthalmology

    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 remaining ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   UC Davis   Julia W. Evans

  8. Optical coherence tomography and Raman spectroscopy of the retina

    Explore Article SPIE Digital Library (Feb 20 2009) Ophthalmology

    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. (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   Julia W. Evans

  9. Comparison of real-time visualization of volumetric OCT data sets by CPU-slicing and GPU-ray casting methods

    Explore Article SPIE Digital Library (Feb 18 2009)

    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. (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   UC Davis

  10. Combined adaptive optics: optical coherence tomography and adaptive optics: scanning laser ophthalmoscopy system for retinal imaging

    Explore Article SPIE Digital Library (Feb 18 2009) Ophthalmology

    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. (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Steven M. Jones   Lawrence Livermore National Laboratory

  11. Microcystoid Maculopathy Associated With Tamoxifen Use Diagnosed By High-Resolution Fourier-Domain Optical Coherence Tomography.

    Explore Article RETINAL Cases & Brief Reports (Jan 9 2009) Ophthalmology

    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 the fovea ... (Read Full Article)

    Comment on Article Mentions:   Zeiss Stratus OCT   John S. Werner   Carl Zeiss Meditec

  12. High-resolution retinal imaging in young children using a handheld scanner and Fourier-domain optical coherence tomography

    Explore Article ScienceDirect (Jan 3 2009) Ophthalmology

    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. Results Useful images were obtained ... (Read Full Article)

    Comment on Article Mentions:   University of Toronto   John S. Werner   UC Davis

  13. Ultra-high-resolution optical coherence tomography gets adaptive-optic ‘glasses’

    Explore Article Laser Focus World (Dec 2 2008) Ophthalmology

    Ultra-high-resolution optical coherence tomography gets adaptive-optic ‘glasses’ Adaptive-optics techniques, which are well known for correcting Earth-based atmospheric effects in astronomical images, are finding new practical application on a smaller scale for retinal imaging. (Read Full Article)

    Comment on Article Mentions:   Lawrence Livermore National Laboratory   Duke University   Superlum

  14. Detailed analysis of retinal function and morphology in a patient with autosomal recessive bestrophinopathy (arb)

    Explore Article SpringerLink Home (Nov 5 2008) Ophthalmology

    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 retinopathy with deposits. Functional assessment revealed normal visual ... (Read Full Article)

    Comment on Article Mentions:   Bioptigen   Universität Rostock   University of Toronto

  15. High-resolution Fourier-Domain Optical Coherence Tomography and Microperimetric Findings After Macula-off Retinal Detachment Repair

    Explore Article OphSource (Aug 3 2008) Ophthalmology

    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 were ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   UC Davis

  16. Fourier-Domain Optical Coherence Tomography and Adaptive Optics Reveal Nerve Fiber Layer Loss and Photoreceptor Changes in a Patient With Optic Nerve Drusen.

    Explore Article Journal of Neuro (Jun 11 2008) Ophthalmology

    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 (Read Full Article)

    Comment on Article Mentions:   Zeiss Stratus OCT   John S. Werner   Robert J. Zawadzki

  17. Retinal Morphological Changes of Patients With X-linked Retinoschisis Evaluated by Fourier-Domain Optical Coherence Tomography

    Explore Article Archives of Ophthalmology (Jun 8 2008) Ophthalmology

    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 the minimum angle of ... (Read Full Article)

    Comment on Article Mentions:   John S. Werner   Robert J. Zawadzki   UC Davis

  18. Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction

    Explore Article opticsinfobase.org (May 20 2008) Ophthalmology

    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)] (Read Full Article)

    Comment on Article Mentions:   Barry Cense   Robert J. Zawadzki   Donald T. Miller

  19. Changes in Cellular Structures Revealed by Ultra-high Resolution Retinal Imaging in Optic Neuropathies

    Explore Article iovs.org (Apr 23 2008) Neurology , Ophthalmology

    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 data sets, ... (Read Full Article)

    Comment on Article Mentions:   Carl Zeiss Meditec   John S. Werner   UC Davis

  20. Improved representation of retinal data acquired with volumetric Fd-OCT: co-registration, visualization and reconstruction of a large field of view

    Explore Article SPIE Digital Library (Feb 11 2008) Ophthalmology

    Robert J. Zawadzki, Alfred R. Fuller, Stacey S. Choi et al. 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 ... [Proc. SPIE Int. Soc. Opt. Eng. 6844, 68440C (2008)] published Mon Feb 11, 2008. (Read Full Article)

    Comment on Article Mentions:   Robert J. Zawadzki

  21. Ultra-high resolution adaptive optics: optical coherence tomography for in vivo imaging of healthy and diseased retinal structures

    Explore Article SPIE Digital Library (Feb 11 2008) Ophthalmology

    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. (Read Full Article)

    Comment on Article Mentions:   Steven M. Jones   Robert J. Zawadzki   John S. Werner

  22. Performance of a MEMS-based AO-OCT system

    Explore Article SPIE Digital Library (Feb 8 2008) Ophthalmology

    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. (Read Full Article)

    Comment on Article Mentions:   Robert J. Zawadzki   Julia W. Evans   John S. Werner

  23. Compact MEMS-based adaptive optics: optical coherence tomography for clinical use

    Explore Article SPIE Digital Library (Feb 8 2008) Ophthalmology

    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 ... (Read Full Article)

    Comment on Article Mentions:   Steven M. Jones   Lawrence Livermore National Laboratory   John S. Werner

  24. Simultaneous imaging of human cone mosaic with adaptive optics enhanced scanning laser ophthalmoscopy and high-speed transversal scanning optical coherence tomography

    Explore Article opticsinfobase.org (Dec 20 2007) Ophthalmology

    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)] (Read Full Article)

    Comment on Article Mentions:   Christoph K. Hitzenberger   John S. Werner   Robert J. Zawadzki

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