1. Articles from Christoph Meier

    1-9 of 9
    1. Selective retina therapy enhanced with optical coherence tomography for dosimetry control and monitoring: a proof of concept study

      Selective retina therapy enhanced with optical coherence tomography for dosimetry control and monitoring: a proof of concept study

      Selective treatment of the retinal pigment epithelium (RPE) by using short-pulse lasers leads to a less destructive treatment for certain retinal diseases in contrast to conventional photocoagulation. The introduction of selective retina therapy (SRT) to clinical routine is still precluded by the challenges to reliably monitor treatment success and to automatically adjust dose within the locally varying therapeutic window. Combining micrometer-scale depth resolving capabilities of optical coherence tomography (OCT) with SRT can yield real-time information on the laser-induced changes within the RPE after a laser pulse or even during treatment with a laser pulse train. In the present study, SRT ...

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    2. Time-Resolved Ultra–High Resolution Optical Coherence Tomography for Real-Time Monitoring of Selective Retina Therapy

      Time-Resolved Ultra–High Resolution Optical Coherence Tomography for Real-Time Monitoring of Selective Retina Therapy

      Purpose : Selective retina therapy (SRT) is a novel treatment for retinal pathologies, solely targeting the RPE. During SRT, the detection of an immediate tissue reaction is challenging, as tissue effects remain limited to intracellular RPE photodisruption. Time-resolved ultra-high axial resolution optical coherence tomography (OCT) is thus evaluated for the monitoring of dynamic optical changes at and around the RPE during SRT. Methods : An experimental OCT system with an ultra-high axial resolution of 1.78 μm was combined with an SRT system and time-resolved OCT M-scans of the target area were recorded from four patients undergoing SRT. Optical coherence tomography scans ...

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    3. Automatic estimation of noise parameters in Fourier-domain optical coherence tomography cross sectional images using statistical information

      Automatic estimation of noise parameters in Fourier-domain optical coherence tomography cross sectional images using statistical information

      Steiner, Patrick; Kowal, Jens H; Pova?ay, Boris; Meier, Christoph; Sznitman, We present an application and sample independent method for the automatic discrimination of noise and signal in optical coherence tomography Bscans. The proposed algorithm models the observed noise probabilistically and allows for a dynamic determination of image noise parameters and the choice of appropriate image rendering parameters. This overcomes the observer variability and the need for a priori information about the content of sample images, both of which are challenging to estimate systematically with current systems. As such, our approach has the advantage of automatically determining crucial parameters for ...

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    4. Assessment of ultra-high resolution optical coherence tomography for monitoring tissue effects caused by laser photocoagulation of ex-vivo porcine retina

      Assessment of ultra-high resolution optical coherence tomography for monitoring tissue effects caused by laser photocoagulation of ex-vivo porcine retina

      Retinal laser photocoagulation is an established and successful treatment for a variety of retinal diseases. While being a valuable treatment modality, laser photocoagulation shows the drawback of employing high energy lasers which are capable of physically destroying the neural retina. For reliable therapy, it is therefore crucial to closely monitor the therapy effects caused in the retinal tissue. A depth resolved representation of optical tissue properties as provided by optical coherence tomography may provide valuable information about the treatment effects in the retinal layers if recorded simultaneously to laser coagulation. Therefore, in this work, the use of ultra-high resolution optical ...

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    5. Fiber-optically integrated cost-effective spectrometer for optical coherence tomography

      Fiber-optically integrated cost-effective spectrometer for optical coherence tomography

      A tilted fiber Bragg grating (TFBG) was integrated as the dispersive element in a high performance biomedical imaging system. The spectrum emitted by the 23 mm long active region of the fiber is projected through custom designed optics consisting of a cylindrical lens for vertical beam collimation and successively by an achromatic doublet onto a linear detector array. High resolution tomograms of biomedical samples were successfully acquired by the frequency domain OCT-system. Tomograms of ophthalmic and dermal samples obtained by the frequency domain OCT-system were obtained achieving 2.84 μm axial and 10.2 μm lateral resolution. The miniaturization reduces ...

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    6. Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating

      A compact, fiber-based spectrometer for biomedical application utilizing a tilted fiber Bragg grating (TFBG) as integrated dispersive element is demonstrated. Based on a 45° UV-written PS750 TFBG a refractive spectrometer with 2.06 radiant/μm dispersion and a numerical aperture of 0.1 was set up and tested as integrated detector for an optical coherence tomography (OCT) system. Featuring a 23 mm long active region at the fiber the spectrum is projected via a cylindrical lens for vertical beam collimation and focused by an achromatic doublet onto the detector array. Covering 740 nm to 860 nm the spectrometer was optically ...

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    7. Design and realization of a spectroscopic optical coherence tomography system for medical applications

      Design and realization of a spectroscopic optical coherence tomography system for medical applications

      In this manuscript, we present the design and realization of a Fourier-Domain Spectroscopic-OCT system with a simple spectrometer, based on off-the-shelf parts and a low-cost, state-of-the-art broadband S-LED light source with three spectrally shifted S-LED modules. Depth resolved spectral absorption measurements in the wavelength range from 750 nm to 850 nm are demonstrated using an expansion of OCT called spectroscopic OCT (SOCT). The realized setup was tested and evaluated towards its ability to measure physical parameters such as blood oxygen saturation quantitatively in vivo. Different sample configurations including multilayer setups and scattering layers were used. Additionally, we present the theoretical ...

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    8. Influence and compensation of autocorrelation terms in depth-resolved spectroscopic Fourier-domain optical coherence tomography

      Influence and compensation of autocorrelation terms in depth-resolved spectroscopic Fourier-domain optical coherence tomography
      We demonstrate depth-resolved spectral absorption measurements in the wavelength range from 750 to 850 nm using a broadband light source consisting of three spectrally shifted superluminescent light-emitting diode modules and a low-cost spectrometer-based Fourier-domain optical coherence tomography system. We present the theoretical model and experimental verification of interferences between autocorrelation terms and the signal carrying cross-correlation terms, strongly affecting the absorption measurements. A simple background subtraction, minimizing the artifacts caused by the interferences of autocorrelation and cross-correlation terms, is presented.
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    9. Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms

      Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms
      In this study, depth resolved measurements of absorption profiles in the wavelength range of 800 nm with a bandwidth of 140 nm are demonstrated using high speed spectroscopic frequency domain OCT(SOCT) and a full range reconstruction algorithm (dispersion encoded full range, DEFR). The feasibility of the algorithm for SOCT is tested in simulation and experiment. With proper calibration, SOCT with DEFR is able to extract absolute, depth resolved absorption profiles over the whole wavelength range at once without the need of tuning and performing measurements at single wavelengths sequentially. The superior acquisition speed and better phase stability in frequency ...
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    1-9 of 9
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  2. Topics in the News

    1. (9 articles) Christoph Meier
    2. (5 articles) Bern University of Applied Sciences
    3. (5 articles) University of Bern
    4. (5 articles) Patrick Steiner
    5. (5 articles) Boris Považay
    6. (3 articles) Volker M. Koch
    7. (2 articles) Ling Wang
    8. (2 articles) Jens H. Kowal
    9. (2 articles) Sebastian Wolf
    10. (1 articles) Wolfgang Drexler
    11. (1 articles) UCLA
    12. (1 articles) University of Wisconsin
    13. (1 articles) University of St. Andrews
    14. (1 articles) Duke University
    15. (1 articles) Kishan Dholakia
    16. (1 articles) Cynthia A. Toth
    17. (1 articles) Richard B. Rosen
    18. (1 articles) Optovue
    19. (1 articles) Leica
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    Spectroscopic measurements with dispersion encoded full range frequency domain optical coherence tomography in single- and multilayered weakly scattering phantoms Influence and compensation of autocorrelation terms in depth-resolved spectroscopic Fourier-domain optical coherence tomography Design and realization of a spectroscopic optical coherence tomography system for medical applications Cost-effective optical coherence tomography spectrometer based on a tilted fiber Bragg grating Fiber-optically integrated cost-effective spectrometer for optical coherence tomography Assessment of ultra-high resolution optical coherence tomography for monitoring tissue effects caused by laser photocoagulation of ex-vivo porcine retina Automatic estimation of noise parameters in Fourier-domain optical coherence tomography cross sectional images using statistical information Time-Resolved Ultra–High Resolution Optical Coherence Tomography for Real-Time Monitoring of Selective Retina Therapy Selective retina therapy enhanced with optical coherence tomography for dosimetry control and monitoring: a proof of concept study Monitoring Response to Platelet-Rich Plasma in Patients with Alopecia Areata with Optical Coherence Tomography: A Case Series NONPERFUSION AREA QUANTIFICATION IN BRANCH RETINAL VEIN OCCLUSION: A WIDEFIELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY STUDY Nonperfusion Assessment in Retinal Vein Occlusion: Comparison between Ultra-Widefield Fluorescein Angiography and Widefield OCT-Angiography