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  1. Article ; Online: Factors Determining Flicker-Induced Retinal Vasodilation in Healthy Subjects.

    Sharifizad, Mozhgan / Witkowska, Katarzyna J / Aschinger, Gerold C / Sapeta, Sabina / Rauch, Alexandra / Schmidl, Doreen / Werkmeister, Rene M / Garhöfer, Gerhard / Schmetterer, Leopold

    Investigative ophthalmology & visual science

    2016  Volume 57, Issue 7, Page(s) 3306–3312

    Abstract: Purpose: The purpose of this study was to analyze factors determining retinal arterial and venous responses to stimulation with diffuse luminance flicker in healthy subjects.: Methods: We retrospectively analyzed results obtained in 374 healthy ... ...

    Abstract Purpose: The purpose of this study was to analyze factors determining retinal arterial and venous responses to stimulation with diffuse luminance flicker in healthy subjects.
    Methods: We retrospectively analyzed results obtained in 374 healthy subjects who had previously participated in clinical studies in our department. A total of 153 subjects underwent a protocol in which flicker stimulation was delivered through the fundus camera at 8 Hz (protocol 1), separating measurement and stimulation light depending on the wavelength, and 221 subjects underwent a protocol in which diffuse luminance flicker was delivered at 12.5 Hz with high modulation depth (protocol 2). We investigated whether sex, systemic blood pressure, baseline vessel size, blood plasma concentration of fasting glucose and hematocrit, and serum concentration of cholesterol, triglycerides, creatinine and C-reactive protein influenced the retinal vascular response to flicker stimulation.
    Results: Flicker responses in arteries and veins were more pronounced in protocol 2 than in protocol 1 (P < 0.001, each). In both of the protocols the vascular response to stimulation with diffuse luminance flicker was larger in smaller vessels (P between 0.001 and 0.016). In protocol 2 the retinal arterial flicker response was negatively associated with cholesterol serum levels (P = 0.033); in protocol 1, only a tendency toward this effect was observed (P = 0.056).
    Conclusions: The present analysis indicates that retinal arterial and venous responses to stimulation with diffuse luminance flicker depend on the way the stimulation is delivered through the fundus camera. In addition, the flicker response varied with vessel size, that is, the smaller the vessel width, the larger the flicker response. Finally, our data indicate that, even within the normal range, higher cholesterol serum levels are associated with lower hyperemic flicker responses.
    MeSH term(s) Adult ; Blood Pressure/physiology ; Cholesterol/blood ; Female ; Humans ; Lighting ; Male ; Photic Stimulation/methods ; Regression Analysis ; Retinal Artery/physiology ; Retinal Artery/radiation effects ; Retinal Vein/physiology ; Retinal Vein/radiation effects ; Retrospective Studies ; Vasodilation/physiology ; Vasodilation/radiation effects
    Chemical Substances Cholesterol (97C5T2UQ7J)
    Language English
    Publishing date 2016-06-22
    Publishing country United States
    Document type Journal Article
    ZDB-ID 391794-0
    ISSN 1552-5783 ; 0146-0404
    ISSN (online) 1552-5783
    ISSN 0146-0404
    DOI 10.1167/iovs.16-19261
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Line-field parallel swept source MHz OCT for structural and functional retinal imaging.

    Fechtig, Daniel J / Grajciar, Branislav / Schmoll, Tilman / Blatter, Cedric / Werkmeister, Rene M / Drexler, Wolfgang / Leitgeb, Rainer A

    Biomedical optics express

    2015  Volume 6, Issue 3, Page(s) 716–735

    Abstract: We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of ... ...

    Abstract We demonstrate three-dimensional structural and functional retinal imaging with line-field parallel swept source imaging (LPSI) at acquisition speeds of up to 1 MHz equivalent A-scan rate with sensitivity better than 93.5 dB at a central wavelength of 840 nm. The results demonstrate competitive sensitivity, speed, image contrast and penetration depth when compared to conventional point scanning OCT. LPSI allows high-speed retinal imaging of function and morphology with commercially available components. We further demonstrate a method that mitigates the effect of the lateral Gaussian intensity distribution across the line focus and demonstrate and discuss the feasibility of high-speed optical angiography for visualization of the retinal microcirculation.
    Language English
    Publishing date 2015-02-04
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2572216-5
    ISSN 2156-7085
    ISSN 2156-7085
    DOI 10.1364/BOE.6.000716
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Single-pulse CARS based multimodal nonlinear optical microscope for bioimaging.

    Kumar, Sunil / Kamali, Tschackad / Levitte, Jonathan M / Katz, Ori / Hermann, Boris / Werkmeister, Rene / Považay, Boris / Drexler, Wolfgang / Unterhuber, Angelika / Silberberg, Yaron

    Optics express

    2015  Volume 23, Issue 10, Page(s) 13082–13098

    Abstract: Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. ... ...

    Abstract Noninvasive label-free imaging of biological systems raises demand not only for high-speed three-dimensional prescreening of morphology over a wide-field of view but also it seeks to extract the microscopic functional and molecular details within. Capitalizing on the unique advantages brought out by different nonlinear optical effects, a multimodal nonlinear optical microscope can be a powerful tool for bioimaging. Bringing together the intensity-dependent contrast mechanisms via second harmonic generation, third harmonic generation and four-wave mixing for structural-sensitive imaging, and single-beam/single-pulse coherent anti-Stokes Raman scattering technique for chemical sensitive imaging in the finger-print region, we have developed a simple and nearly alignment-free multimodal nonlinear optical microscope that is based on a single wide-band Ti:Sapphire femtosecond pulse laser source. Successful imaging tests have been realized on two exemplary biological samples, a canine femur bone and collagen fibrils harvested from a rat tail. Since the ultra-broad band-width femtosecond laser is a suitable source for performing high-resolution optical coherence tomography, a wide-field optical coherence tomography arm can be easily incorporated into the presented multimodal microscope making it a versatile optical imaging tool for noninvasive label-free bioimaging.
    Language English
    Publishing date 2015-05-18
    Publishing country United States
    Document type Journal Article
    ZDB-ID 1491859-6
    ISSN 1094-4087 ; 1094-4087
    ISSN (online) 1094-4087
    ISSN 1094-4087
    DOI 10.1364/OE.23.013082
    Database MEDical Literature Analysis and Retrieval System OnLINE

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