Lasermaterialbearbeitung

Das BMO kooperiert eng mit dem MLL auf dem Gebiet der Lasermaterial-bearbeitung. Es stehen verschiedene Lasersysteme für den UV - Bereich für die Oberflächenbearbeitung von Kunststoffen und Gläsern zur Verfügung. Nähere Informationen finden Sie auch auf den Seiten des Medizinischen Laserzentrums.

Durch Lasermaterialbearbeitung erzeugte Löcher in verschiedenen Kunststoffen und Knorpelgewebe.

Publikation

998

  • Brinkmann, R. and Koop, N. and Geerling, G. and Kampmeier, J. and Borcherding, S. and Kamm, K. and Birngruber, R.: Diode laser thermokeratoplasty: application strategy and dosimetry. J Cataract Refract Surg, no. 24, pp. 1195-207, 998
    BibTeX
    @article{Brinkmann1998,
       author = {Brinkmann, R. and Koop, N. and Geerling, G. and Kampmeier, J. and Borcherding, S. and Kamm, K. and Birngruber, R.},
       title = {Diode laser thermokeratoplasty: application strategy and dosimetry},
       journal = {J Cataract Refract Surg},
       volume = {24},
       number = {9},
       pages = {1195-207},
       note = {0886-3350 (Print)
    Journal Article
    Research Support, Non-U.S. Gov't},
       abstract = {PURPOSE: To investigate suitable application parameters for efficient hyperopic correction by laser thermokeratoplasty (LTK) using mid-infrared laser diodes. SETTING: Medical Laser Center Lubeck, Lubeck, Germany. METHOD: A tunable continuous-wave laser diode in the spectral range between 1.845 and 1.871 microns was used. Transmitted by waveguides, the laser energy was used to induce coagulations on freshly enucleated porcine eyes to increase corneal curvature. The coagulations were equidistantly applied by a fiber-cornea contact and a noncontact focusing device that were adjusted on a ring concentric to the corneal apex. Different laser parameters and application geometries were evaluated. Refractive changes were measured by computer-assisted corneal topography before and after treatment. Polarization light microscopy and temperature calculations were used to analyze the coagulations. RESULTS: Because of the tunability of the laser diode, the influence of the corneal absorption coefficient (between 0.9 and 1.6 mm-1) on the refractive change could be measured. A laser power between 125 and 200 mW was adequate to achieve refractive changes up to 10.0 diopters. In the preferable focusing device, the refractive change increased almost logarithmically with the irradiation time up to 15 seconds. The number of coagulations on a fixed application ring showed no significant influence on refractive change; however, it showed an almost linear decrease with increasing ring diameter from 5.0 to 10.0 mm. Histological analysis revealed 3 stages of thermal damage. CONCLUSION: Diode LTK provided defined and uniform coagulations when using a well-adapted focusing device, resulting in sufficient refractive change. The results indicate that diode LTK is superior to pulsed holmium LTK.},
       keywords = {Absorption
    Animals
    Cornea/pathology/physiopathology/*surgery
    Hyperopia/pathology/physiopathology/*surgery
    Laser Coagulation/*methods
    Microscopy, Polarization
    Refraction, Ocular
    Swine},
       year = {1998}
    }
    

2015

  • Klinger, A. and Krapf, L. and Orzekowsky-Schroeder, R. and Koop, N. and Vogel, A. and Huttmann, G.: Intravital autofluorescence 2-photon microscopy of murine intestinal mucosa with ultra-broadband femtosecond laser pulse excitation: image quality, photodamage, and inflammation. J Biomed Opt, no. 20, pp. 116001, 2015
    BibTeX Link
    @article{Klinger2017,
       author = {Klinger, A. and Krapf, L. and Orzekowsky-Schroeder, R. and Koop, N. and Vogel, A. and Huttmann, G.},
       title = {Intravital autofluorescence 2-photon microscopy of murine intestinal mucosa with ultra-broadband femtosecond laser pulse excitation: image quality, photodamage, and inflammation},
       journal = {J Biomed Opt},
       volume = {20},
       number = {11},
       pages = {116001},
       ISSN = {1083-3668},
       DOI = {10.1117/1.jbo.20.11.116001},
       year = {2015},
       type = {Journal Article}
    }
    

2013

  • Miura, Y. and Huettmann, G. and Orzekowsky-Schroeder, R. and Steven, P. and Szaszak, M. and Koop, N. and Brinkmann, R.: Two-Photon Microscopy and Fluorescence Lifetime Imaging of Retinal Pigment Epithelial Cells under Oxidative Stress. Invest Ophthalmol Vis Sci, 2013
    BibTeX Link
    @article{Miura2013,
       author = {Miura, Y. and Huettmann, G. and Orzekowsky-Schroeder, R. and Steven, P. and Szaszak, M. and Koop, N. and Brinkmann, R.},
       title = {Two-Photon Microscopy and Fluorescence Lifetime Imaging of Retinal Pigment Epithelial Cells under Oxidative Stress},
       journal = {Invest Ophthalmol Vis Sci},
       note = {Miura, Yoko
    Huettmann, Gereon
    Orzekowsky-Schroeder, Regina
    Steven, Philipp
    Szaszak, Marta
    Koop, Norbert
    Brinkmann, Ralf
    ENG
    2013/04/06 06:00
    Invest Ophthalmol Vis Sci. 2013 Apr 4. pii: iovs.13-11808v1. doi: 10.1167/iovs.13-11808.},
       abstract = {PURPOSE: The aim of this study was to investigate the autofluorescence (AF) of the RPE with two-photon microscopy (TPM) and fluorescence lifetime imaging (FLIM) under normal and oxidative stress conditions. METHODS: Porcine RPE-choroid explants were used for investigation. The RPE-choroid tissue was preserved in a perfusion organ culture system. Oxidative stress was induced by laser photocoagulation with frequency-doubled Nd:YAG laser (532 nm) and by exposure to different concentrations (0, 1, 10 mM) of ferrous sulfate (FeSO4) for 1 hr. At indicated time points after exposure, the tissue was examined with TPM and FLIM. Intracellular reactive oxygen species around the photocoagulation lesion were detected with chloromethyl-2'7'-dichlorofluorescein diacetate (CM-H2DCFDA). Melanosomes were isolated from RPE cells and its fluorescence properties were investigated under normal and oxidized conditions. RESULTS: Under normal condition, AF in RPE cells with TPM is mostly originated from melanosomes, which has a very short fluorescence lifetime (FLT) (mean=117 ps). Under oxidative stress induced by laser irradiation and FeSO4 exposure, bright granular AF appears inside and around RPE cells, whose FLT is significantly longer (mean=1388 ps) than the FLT of the melanosome-AF. Excitation and emission peaks are found at 710-750 nm and 450-500 nm, respectively. Oxidative stress increases the fluorescence intensity of the melanosomes but does not change their FLT. CONCLUSION: TPM reveals acute oxidative stress-induced bright AF granules inside and around RPE cells which can be clearly discriminated from melanosomes by FLIM. TPM combined with FLIM is a useful tool of live-cell analysis to investigate functional alterations of the RPE.},
       year = {2013}
    }
    
  • Miura, Y and Huettmann, G and Orzekowsky-Schroeder, R and Steven, P and Szaszák, M and Koop, N and Brinkmann, R: Two-photon Microscopy and Fluorescence Lifetime Analysis of Lipid Peroxidation Product in Photoreceptor Outer Segment and in Retinal Pigment Epithelial Cell. ARVO Meeting Abstracts, March 26, 2012, 2013
    BibTeX Link
    @misc{Miura2013,
       author = {Miura, Y and Huettmann, G and Orzekowsky-Schroeder, R and Steven, P and Szaszák, M and Koop, N and Brinkmann, R },
       title = {Two-photon Microscopy and Fluorescence Lifetime Analysis of Lipid Peroxidation Product in Photoreceptor Outer Segment and in Retinal Pigment Epithelial Cell},
       publisher = {ARVO Meeting Abstracts},
       month = {March 26, 2012 },
       url = {http://www.abstractsonline.com/Plan/ViewAbstract.aspx?sKey=57630548-893d-4e45-9ddc-b6f547dd4ff0&cKey=d08a30bc-fe98-40a2-8a1c-1b171e4becd3&mKey=f0fce029-9bf8-4e7c-b48e-9ff7711d4a0e},
       year = {2013},
       type = {Poster}
    }
    
  • Koop, N: Schreib‘ mal wieder! Neue Laser-Markierungsverfahren und spezielle Mikrobearbeitungen. GIT Labor-Fachzeitschrift, 2013
    BibTeX
    @article{Koop2013,
       author = {Koop, N},
       title = {Schreib‘ mal wieder! Neue Laser-Markierungsverfahren und spezielle Mikrobearbeitungen},
       journal = {GIT Labor-Fachzeitschrift},
       number = {9},
       year = {2013},
       type = {Journal Article}
    }
    

2012

  • Gehlsen, U. and Oetke, A. and Szaszak, M. and Koop, N. and Paulsen, F. and Gebert, A. and Huettmann, G. and Steven, P.: Two-photon fluorescence lifetime imaging monitors metabolic changes during wound healing of corneal epithelial cells in vitro. Graefes Arch Clin Exp Ophthalmol, no. 6, pp. 6, 2012
    BibTeX
    @article{Gehlsen,
       author = {Gehlsen, U. and Oetke, A. and Szaszak, M. and Koop, N. and Paulsen, F. and Gebert, A. and Huettmann, G. and Steven, P.},
       title = {Two-photon fluorescence lifetime imaging monitors metabolic changes during wound healing of corneal epithelial cells in vitro},
       journal = {Graefes Arch Clin Exp Ophthalmol},
       volume = {6},
       pages = {6},
       note = {Using Smart Source Parsing
    May},
       abstract = {BACKGROUND: Early and correct diagnosis of delayed or absent corneal epithelial wound healing is a key factor in the prevention of infection and consecutive destruction of the corneal stroma with impending irreversible visual loss. Two-photon microscopy (TPM) is a novel technology that has potential to depict epithelial cells and to evaluate cellular function by measuring autofluorescence properties such as fluorescence intensity and fluorescence lifetimes of metabolic co-factors such as NAD(P)H. METHODS: Using non-invasive TPM in a tissue-culture scratch model and an organ-culture erosion model, fluorescence intensity and fluorescence lifetimes of NAD(P)H were measured before and during closure of the epithelial wounds. Influence of temperature and selective inhibition of metabolism on intensity and lifetimes were tested additionally. RESULTS: Decrease of temperature resulted in significant increase of fluorescence lifetimes and decrease of the relative amount of free NAD(P)H due to decreased global metabolism. Increase in temperature and upregulation of glycolysis through blocking the mitochondrial electron transport chain by rotenone resulted in increased intensity, decreased lifetimes and increase in the relative amount of free NAD(P)H. Changes of lifetimes and free:protein-bound NAD(P)H ratios were similar to changes measured during wound healing in both scratch and erosion models. CONCLUSIONS: Fluorescence lifetime measurements (FLIM) detected enhancement of cellular metabolism following epithelial damage in both models. The prospective detection of cellular autofluorescence in vivo, in particular FLIM of metabolic cofactor NAD(P)H, has the potential to become an indispensible tool in clinical use to differentiate healing from non-healing epithelial cells and to evaluate effects of newly developed substances on cellular metabolism in preclinical and clinical trials.},
       year = {2012}
    }
  • Klinger, A. and Orzekowsky-Schroeder, R. and von Smolinski, D. and Blessenohl, M. and Schueth, A. and Koop, N. and Hüttmann, G. and Gebert, A.: Complex morphology and functional dynamics of vital murine intestinal mucosa revealed by autofluorescence 2-photon microscopy. Histochem Cell Biol, no. 137, pp. 269-278, 2012
    BibTeX Link
    @article{Klinder2017,
       author = {Klinger, A. and Orzekowsky-Schroeder, R. and von Smolinski, D. and Blessenohl, M. and Schueth, A. and Koop, N. and Hüttmann, G. and Gebert, A.},
       title = {Complex morphology and functional dynamics of vital murine intestinal mucosa revealed by autofluorescence 2-photon microscopy},
       journal = {Histochem Cell Biol},
       volume = {137},
       number = {3},
       pages = {269-278},
       ISSN = {1432-119X (Electronic)
    0948-6143 (Linking)},
       DOI = {10.1007/s00418-011-0905-0},
       year = {2012},
       type = {Journal Article}
    }
    

2009

  • Tiede, S. and Koop, N. and Kloepper, J. E. and Fassler, R. and Paus, R.: Nonviral in situ green fluorescent protein labeling and culture of primary, adult human hair follicle epithelial progenitor cells. Stem Cells, no. 27, pp. 2793-803, 2009
    BibTeX Link
    @article{Tiede2009,
       author = {Tiede, S. and Koop, N. and Kloepper, J. E. and Fassler, R. and Paus, R.},
       title = {Nonviral in situ green fluorescent protein labeling and culture of primary, adult human hair follicle epithelial progenitor cells},
       journal = {Stem Cells},
       volume = {27},
       number = {11},
       pages = {2793-803},
       ISSN = {1066-5099},
       DOI = {10.1002/stem.213},
       year = {2009},
       type = {Journal Article}
    }
    
  • Steven, Philipp and Müller, Maya and Koop, Norbert and Rose, Christian and Hüttmann, Gereon: Comparison of Cornea Module and DermaInspect for noninvasive imaging of ocular surface pathologies. Journal of Biomedical Optics, no. 14, pp. 064040-064040, 2009
    BibTeX
    @article{Steven,
       author = {Steven, Philipp and Müller, Maya and Koop, Norbert and Rose, Christian and Hüttmann, Gereon},
       title = {Comparison of Cornea Module and DermaInspect for noninvasive imaging of ocular surface pathologies},
       journal = {Journal of Biomedical Optics},
       volume = {14},
       number = {6},
       pages = {064040-064040},
       note = {10.1117/1.3275475},
       abstract = {Minimally invasive imaging of ocular surface pathologies aims at securing clinical diagnosis without actual tissue probing. For this matter, confocal microscopy (Cornea Module) is in daily use in ophthalmic practice. Multiphoton microscopy is a new optical technique that enables high-resolution imaging and functional analysis of living tissues based on tissue autofluorescence. This study was set up to compare the potential of a multiphoton microscope (DermaInspect) to the Cornea Module. Ocular surface pathologies such as pterygia, papillomae, and nevi were investigated in vivo using the Cornea Module and imaged immediately after excision by DermaInspect. Two excitation wavelengths, fluorescence lifetime imaging and second-harmonic generation (SHG), were used to discriminate different tissue structures. Images were compared with the histopathological assessment of the samples. At wavelengths of 730nm, multiphoton microscopy exclusively revealed cellular structures. Collagen fibrils were specifically demonstrated by second-harmonic generation. Measurements of fluorescent lifetimes enabled the highly specific detection of goblet cells, erythrocytes, and nevus-cell clusters. At the settings used, DermaInspect reaches higher resolutions than the Cornea Module and obtains additional structural information. The parallel detection of multiphoton excited autofluorescence and confocal imaging could expand the possibilities of minimally invasive investigation of the ocular surface toward functional analysis at higher resolutions.},
       year = {2009}
    }

2008

  • Mueller, M. and Huettmann, G. and Koop, N. and Steven, P.: Minimal-Invasive Imaging of Ocular Surface Pathologies - Confocal vs. Two-Photon Microscopy. Investigative Ophthalmology & Visual Science, no. 49, pp. 2258-2258, 2008
    BibTeX Link
    @article{Mueller2008,
       author = {Mueller, M. and Huettmann, G. and Koop, N. and Steven, P.},
       title = {Minimal-Invasive Imaging of Ocular Surface Pathologies - Confocal vs. Two-Photon Microscopy},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {49},
       number = {13},
       pages = {2258-2258},
       ISSN = {1552-5783},
       url = {http://dx.doi.org/},
       year = {2008},
       type = {Journal Article}
    }
    
  • Qu, X. and Wang, J. and Zhang, Z. and Koop, N. and Rahmanzadeh, R. and Huttmann, G.: Imaging of cancer cells by multiphoton microscopy using gold nanoparticles and fluorescent dyes. no. 13, pp. 031217, 2008
    BibTeX
    @misc{Qu,
       author = {Qu, X. and Wang, J. and Zhang, Z. and Koop, N. and Rahmanzadeh, R. and Huttmann, G.},
       title = {Imaging of cancer cells by multiphoton microscopy using gold nanoparticles and fluorescent dyes},
       volume = {13},
       number = {3},
       pages = {031217},
       note = {Using Smart Source Parsing
    May-Jun},
       abstract = {Due to their unique optical properties, optical probes, including metal nanoparticles (NPs) and fluorescent dyes, are increasingly used as labeling tools in biological imaging. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) at 750-nm excitation, we recorded intensity and FLIM images from gold NPs (30 nm) and the fluorescent dye Alexa 488 (A488) conjugated with monoclonal ACT-1 antibodies as well as Hoechst 33258 (H258) after incubation with the lymphoma cell line (Karpas-299). From the FLIM images, we can easily discriminate the imaging difference between cells and optical probes according to their distinct fluorescence lifetimes (cellular autofluorescence: 1 to 2 ns; gold NPs: <0.02 ns; A488: 3.5 ns; H258: 2.5 ns). The NP-ACT-1 and A488-ACT-1 conjugates were bound homogeneously on the surface of cells, whereas H258 stained the cell nucleus. We demonstrate that the emission intensity of gold NPs is about ten times stronger than that of the autofluorescence of Karpas-299 cells at the same excitation power. Compared with fluorescent dyes, stronger emission is also observed from gold NPs. Together with their high photostability, these observations suggest that gold NPs are a viable alternative to fluorescent dyes for cellular imaging and cancer diagnosis.},
       ISBN = {1083-3668 (Print)
    1083-3668 (Linking)},
       year = {2008}
    }
  • Steven, P. and Rupp, J. and Huttmann, G. and Koop, N. and Lensing, C. and Laqua, H. and Gebert, A.: Experimental induction and three-dimensional two-photon imaging of conjunctiva-associated lymphoid tissue. Invest Ophthalmol Vis Sci, no. 49, pp. 1512-7, 2008
    BibTeX
    @article{Steven,
       author = {Steven, P. and Rupp, J. and Huttmann, G. and Koop, N. and Lensing, C. and Laqua, H. and Gebert, A.},
       title = {Experimental induction and three-dimensional two-photon imaging of conjunctiva-associated lymphoid tissue},
       journal = {Invest Ophthalmol Vis Sci},
       volume = {49},
       number = {4},
       pages = {1512-7},
       note = {Using Smart Source Parsing
    Apr},
       abstract = {PURPOSE: Conjunctiva-associated lymphoid tissue (CALT) is assumed to be a key location for the generation of adaptive immune mechanisms of the ocular surface, but functional studies of CALT are still lacking. The purpose of this study was to establish an animal model that enables functional analysis of immune mechanisms going on within CALT. In addition, the use of two-photon microscopy, a new optical method, was evaluated for examining complex immunologic interactions of CALT by volume (three-dimensional [3-D]) and time-dependence (four-dimensional [4-D]) in vivo. METHODS: The conjunctiva of female BALB/c mice was repeatedly challenged with topical Chlamydia trachomatis serovar C or a solution of ovalbumin and cholera toxin B. Two-photon microscopy was conducted on explanted, unfixed, and unstained eyes with adjacent nictitating membranes. RESULTS: After three to five stimulations, CALT was detected exclusively in the nictitating membrane of 73% (C. trachomatis) or 70% (ovalbumin/ cholera toxin) of the animals. CALT mainly consisted of CD45R/B220+ B cells and CD4+ and CD8+ T cells. Electron microscopy showed intraepithelial lymphocytes and follicles consisting of lymphocytes, dendritic cells, and macrophages. Two-photon microscopy based on tissue autofluorescence allowed all components of CALT to be detected three dimensionally. High-resolution images were generated in tissue depths of 65 microm below the mucosal surface. CONCLUSIONS: This study introduces a novel mouse model for functional investigations of CALT. Topical stimulation with C. trachomatis or ovalbumin/cholera toxin B reliably leads to CALT generation at the nictitating membrane. The use of two-photon microscopy enables groundbreaking 3-D and, in the future, intravital 4-D investigations of immunologic processes initiated in CALT.},
       year = {2008}
    }

2007

  • Steven, P. and Rupp, J. and Huettmann, G. and Koop, N. and Laqua, H.: Two-Photon Real-Time Imaging of Conjunctiva-Associated Lymphoid Tissue (CALT). Investigative Ophthalmology & Visual Science, no. 48, pp. 201-201, 2007
    BibTeX Link
    @article{Steven2007,
       author = {Steven, P. and Rupp, J. and Huettmann, G. and Koop, N. and Laqua, H.},
       title = {Two-Photon Real-Time Imaging of Conjunctiva-Associated Lymphoid Tissue (CALT)},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {48},
       number = {13},
       pages = {201-201},
       abstract = {AbstractPurpose:: Immunological real-time analysis of conjunctiva-associated lymphoid tissue (CALT) is challenging at state. For the first time, two-photon microscopy, a new optical method, is evaluated in its use to analyze morphology and function of CALT. Methods:: Conjunctiva of female Balb/c mice is challenged with Chlamydia trachomatis serovar C (ChtC) or ovalbumin and choleratoxin subunit B (OVA/CTB) for CALT induction. A two-photon microscope equipped with a near infrared femtosecond-laser and a fluorescence-lifetime detector is used for ex-vivo analysis of unfixed and unstained ocular tissue with additional application of fluorescent microspheres to demonstrate transepithelial particle transport. Results:: Challenge with ChtC or OVA/CTB induce all CALT components (lymphoepithelium, follicles, blood and lymphatic vessels), that are demonstrated in cellular and subcellular resolution by means of autofluorescence imaging. Wavelength adaptation allows specific differentiation of cellular and acellular components. Fluorescence-lifetime detection permits differentiation of cellular subsets (e.g. lymphocytes and macrophages). Application of fluorescent microspheres demonstrates transepithelial particle transport and detection within intracellular vesicles. Conclusions:: Two-photonmicroscopy is an innovative optical technique to analyse morphological and functional features of CALT. Detection of transepithelial particle transport and its impact on conjunctival immunological processes can be visualized in real-time. Future in-vivo experiments with suitable animal models would allow detailed analysis of CALT in a clinical context e.g. corneal transplant rejection, keratoconjunctivitis sicca and follicular conjunctivitis.},
       ISSN = {1552-5783},
       url = {http://dx.doi.org/},
       year = {2007},
       type = {Journal Article}
    }
    
  • Rusanov, V. and Paulsen, H. and Böttger, L. H. and Winkler, H. and Wolny, J. A. and Koop, N. and Dorn, Th. and Janiak, C. and Trautwein, A. X.: Mössbauer, nuclear inelastic scattering and density functional studies on the second metastable state of Na2[Fe(CN)5NO]·2H2O. Hyperfine Interactions, no. 175, pp. 141-150, 2007
    BibTeX Link Link
    @article{Rusanov2007,
       author = {Rusanov, V. and Paulsen, H. and Böttger, L. H. and Winkler, H. and Wolny, J. A. and Koop, N. and Dorn, Th. and Janiak, C. and Trautwein, A. X.},
       title = {Mössbauer, nuclear inelastic scattering and density functional studies on the second metastable state of Na2[Fe(CN)5NO]·2H2O},
       journal = {Hyperfine Interactions},
       volume = {175},
       number = {1},
       pages = {141-150},
       abstract = {The structure of the light-induced metastable state SII of Na2[Fe(CN)5NO]·2H2O was investigated by transmission Mössbauer spectroscopy (TMS) in the temperature range between 85 and 135 K, nuclear inelastic scattering (NIS) at 98 K using synchrotron radiation and density functional theory (DFT) calculations. The DFT and TMS results strongly support the view that the NO group in SII takes a side-on molecular orientation and, further, is dynamically displaced from one eclipsed, via a staggered, to a second eclipsed orientation. The population conditions for generating SII are optimal for measurements by TMS, yet they are modest for accumulating NIS spectra. Optimization of population conditions for NIS measurements is discussed and new NIS experiments on SII are proposed.},
       ISSN = {1572-9540},
       DOI = {10.1007/s10751-008-9598-8},
       url = {http://dx.doi.org/10.1007/s10751-008-9598-8},
       year = {2007},
       type = {Journal Article}
    }
    

2002

  • Brinkmann, R. and Koop, N. and Oezdemir, M. and Alt, C. and Schuele, G. and Lin, C. P. and Birngruber, R.: Selective RPE damage by means of a rapidly scanned cw laser beam. Investigative Ophthalmology & Visual Science, no. 43, pp. U595-U595, 2002
    BibTeX Link
    @article{Brinkmann2002,
       author = {Brinkmann, R. and Koop, N. and Oezdemir, M. and Alt, C. and Schuele, G. and Lin, C. P. and Birngruber, R.},
       title = {Selective RPE damage by means of a rapidly scanned cw laser beam},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {43},
       pages = {U595-U595},
       note = {Suppl. 1
    709CF
    2535
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:000184606602467},
       year = {2002},
       type = {Journal Article}
    }
    
  • Brinkmann, R and Koop, N and Özdemir, M and Alt, C and Schüle, G and Lin, C P and Birngruber, R: Selective damage of pigmented cells by means of a rapidly scanned cw laser beam. Proc SPIE, no. 4617, pp. 134-140, 2002
    BibTeX
    @article{Brinkmann2002,
       author = {Brinkmann, R  and Koop, N and Özdemir, M  and Alt, C and Schüle, G and Lin, C P and Birngruber, R},
       title = {Selective damage of pigmented cells by means of a rapidly scanned cw laser beam},
       journal = {Proc SPIE},
       volume = {4617},
       pages = {134-140},
       year = {2002},
       type = {Journal Article}
    }
    

2000

  • Brinkmann, R. and Radt, B. and Flamm, C. and Kampmeier, J. and Koop, N. and Birngruber, R.: Influence of temperature and time on thermally induced forces in corneal collagen and the effect on laser thermokeratoplasty. J Cataract Refract Surg, no. 26, pp. 744-54, 2000
    BibTeX Link
    @article{Brinkmann2000,
       author = {Brinkmann, R. and Radt, B. and Flamm, C. and Kampmeier, J. and Koop, N. and Birngruber, R.},
       title = {Influence of temperature and time on thermally induced forces in corneal collagen and the effect on laser thermokeratoplasty},
       journal = {J Cataract Refract Surg},
       volume = {26},
       number = {5},
       pages = {744-54},
       note = {0886-3350 (Print)
    Journal Article
    Research Support, Non-U.S. Gov't},
       abstract = {PURPOSE: To investigate thermomechanical aspects of corneal collagen denaturation as a function of temperature and time and the effect of the induced forces on refractive changes with laser thermokeratoplasty (LTK). SETTING: Medical Laser Center Lubeck, Lubeck, Germany. METHODS: In a material-test setup, porcine corneal strips were denatured in paraffin oil at various constant temperatures for 10 and 500 seconds, and the temporal course of the contractive forces was studied under isometric conditions. Typical LTK lesions were performed in porcine eyes in vitro with a continuous-wave infrared laser diode at a wavelength of 1.87 microm for 10 and 60 seconds. The laser power was chosen to achieve comparable denatured volumes at both irradiation times. The refractive changes were measured and analyzed by histologic evaluations and temperature calculations. RESULTS: The time course of the induced forces was characterized by a maximal force, which increased almost linearly with temperature, and a residual lower force. After 500 seconds of heating, the highest force was achieved with a temperature of 75 degrees C. With a limited heating period of only 10 seconds, the forces steadily increased with temperature over the entire observation period. Laser thermokeratoplasty produced less refractive change after 10 seconds of irradiation than after 60 seconds, although the laser power was 25% higher in the short heating period. Polarization light microscopy of LTK lesions revealed different stages of thermal damage. CONCLUSION: The course of the contractive forces during and after heating is a complicated function of the spatial time/temperature profile. Laser thermokeratoplasty lesions produced with 2 irradiation times showed different stages of denaturation and induced refractive change.},
       keywords = {Animals
    Body Temperature
    Collagen/*metabolism
    Cornea/metabolism/pathology/*surgery
    *Laser Coagulation
    Microscopy, Polarization
    Protein Denaturation
    Swine
    Time Factors},
       url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=10831907},
       year = {2000},
       type = {Journal Article}
    }
    
  • Wirbelauer, C. and Koop, N. and Tuengler, A. and Geerling, G. and Birngruber, R. and Laqua, H. and Brinkmann, R.: Corneal endothelial cell damage after experimental diode laser thermal keratoplasty. J Refract Surg, no. 16, pp. 323-9, 2000
    BibTeX
    @article{Wirbelauer2000,
       author = {Wirbelauer, C. and Koop, N. and Tuengler, A. and Geerling, G. and Birngruber, R. and Laqua, H. and Brinkmann, R.},
       title = {Corneal endothelial cell damage after experimental diode laser thermal keratoplasty},
       journal = {J Refract Surg},
       volume = {16},
       number = {3},
       pages = {323-9},
       note = {Wirbelauer, C
    Koop, N
    Tuengler, A
    Geerling, G
    Birngruber, R
    Laqua, H
    Brinkmann, R
    Journal Article
    United States
    J Refract Surg. 2000 May-Jun;16(3):323-9.},
       abstract = {PURPOSE: To evaluate the safety of diode laser thermal keratoplasty (LTK) with respect to corneal endothelial cell damage. METHODS: In an in vitro animal model system, porcine eyes were irradiated with a continuously emitting laser diode at wavelengths (lambda) of 1.85 or 1.87 microm, corresponding to an absorption coefficient (micro(a)) of 1.1 or 2.0 mm(-1). Different irradiation and application parameters were tested serially. To determine the temperature threshold for endothelial damage, corneal buttons were analyzed separately in a waterbath experiment. The endothelial damage was assessed after trypan blue and alizarin red supravital staining under light microscopy. RESULTS: The thresholds for the 50% probability of thermal damage (ED50) were determined at corneal temperatures of 65 degrees C for a 10-second water-bath immersion, and 59 degrees C for 60 seconds. Coagulations that reached the deeper stromal layers revealed severe endothelial cellular alterations and areas of exposed Descemet's membrane. The thermally induced changes were dependent on laser power and the absorption coefficient (wavelength). Mean diameter of total endothelial cell damage was 245 +/- 154 microm (range, 0 to 594 microm) for an absorption coefficient of 1.1 mm(-1). The maximal lateral extent of endothelial cell damage induced by the laser exposure was 594 microm in diameter. Increasing the absorption coefficient decreased the penetration depth of the laser irradiation, creating a greater temperature rise within the corneal stroma and significantly less endothelial damage (P < .01), when the same laser power was applied. The calculated total area of damage for the paracentral human corneal endothelium ranged from 1.8% to 13.6%. CONCLUSION: Data obtained in this in vitro study were transferred to an endothelial cell damage nomogram, demonstrating that appropriate parameter improvements can minimize the adverse effects to the corneal endothelium. However, model adjustment to the human cornea indicates the potential for endothelial cell damage after diode laser thermal keratoplasty, and should be considered when performing this elective procedure.},
       keywords = {Animals
    Anthraquinones
    Cell Count
    Cell Survival
    Corneal Diseases/*etiology/pathology
    Corneal Stroma/*surgery
    Endothelium, Corneal/*pathology
    Laser Coagulation/*adverse effects/methods
    Necrosis
    Safety
    Swine
    Trypan Blue},
       ISSN = {1081-597X (Print)
    1081-597x},
       year = {2000},
       type = {Journal Article}
    }
    

1999

  • Koop, N. and Wirbelauer, C. and Tüngler, A. and Geerling, G. and Bastian, G. O. and Brinkmann, R: Thermische Schädigung des Hornhautendothels bei der Dioden-Laserthermokeratoplastik.. Ophthalmologe, no. 96, pp. 392-397, 1999
    BibTeX
    @article{Koop,
       author = {Koop, N. and Wirbelauer, C. and Tüngler, A. and Geerling, G. and Bastian, G. O. and Brinkmann, R},
       title = {Thermische Schädigung des Hornhautendothels bei der Dioden-Laserthermokeratoplastik.},
       journal = {Ophthalmologe},
       volume = {96},
       pages = {392-397},
       year = {1999},
       type = {Journal Article}
    }
    
  • Geerling, G. and Koop, N. and Tungler, A. and Brinkmann, R. and Wirbelauer, C. and Birngruber, R. and Laqua, H.: Diode laser thermokeratoplasty. Initial clinical experiences. Ophthalmologe, no. 96, pp. 306-11, 1999
    BibTeX
    @article{Geerling1999,
       author = {Geerling, G. and Koop, N. and Tungler, A. and Brinkmann, R. and Wirbelauer, C. and Birngruber, R. and Laqua, H.},
       title = {Diode laser thermokeratoplasty. Initial clinical experiences},
       journal = {Ophthalmologe},
       volume = {96},
       number = {5},
       pages = {306-11},
       abstract = {PURPOSE: Pulsed holmium lasers are currently used to correct hyperopia by means of laser thermokeratoplasty (LTK). Series of microsecond laser pulses are applied with a high repetition rate to induce shrinkage of corneal collagen fibers. The pulsed energy application results in intrastromal temperature peaks of up to 200 degrees C. A continuously emitting laser diode can--as we demonstrated recently in an invivo study on minipigs--be used for LTK and may be of advantage because the temperature rise is more steady. The aim of this study was to examine the safety, amount, and stability of hyperopic correction of diode LTK on blind human eyes. METHODS: We used a laserdiode that was set to continuously emit light at lambda = 1.854 microns/mu a = 1.04 mm-1 (group I, n = 4) or 1.87 microns/mu a = 1.92 mm-1 (group II, n = 4). Radiation energy was 100 to 150 mW for 10 s per coagulation. Eight coagulations on a single ring (group I) and 16 coagulations on a double ring (group II) diameter were applied in the cornea concentric to the entrance pupil by means of a vacuum-fixed application mask (group I = conjunctival fixation; group II = corneal fixation) and a handpiece with a focusing optic. Preoperatively as well as 1 week, 1, 2, 3, 6 12 and 18 months postoperative ophthalmologic controls were performed and the corneal refractive power was measured. RESULTS: In group I initial refractive changes of up to +4.9 D were achieved (1 week postoperative). However, due to the great penetration depth of the laser irradiation, large endothelial defects resulted beneath the stromal coagulations. In group II an initial refractive change of up to +6.8 D was achieved and as a result of the reduced penetration depth, the endothelial cell damage was much reduced. Partial regression of the refractive effect occurred in all subjects, which continued in higher refractive changes during the 2nd postoperative year. The refractive effect at 12 months was +0.6 to +1.5 D in group I and +0.9 to +5.7 D in group II. At 12 months the induced astigmatism was 0.5 to 2.2 D in group I and 0.3 to 1.6 D in group II. No serious adverse effects were noticed. CONCLUSION: A continously emitting laser diode working at a wavelength of 1.87 microns can be used to correct hyperopia by means of LTK safely and effectively. Regression occurs predominantly in the first 6 postoperative months. Further studies must be conducted to determine the importance of patient inherent parameters such as age in establishing a nomogram.},
       keywords = {Adult
    Aged
    Aged, 80 and over
    Blindness/*surgery
    Corneal Topography
    English Abstract
    Equipment Safety
    Female
    Human
    Hyperopia/*surgery
    Keratectomy, Photorefractive, Excimer Laser/*instrumentation
    Laser Coagulation/*instrumentation
    Male
    Middle Age
    Postoperative Complications/etiology
    Refraction, Ocular
    Temperature},
       year = {1999},
       type = {Journal Article}
    }
    
  • Geerling, G. and Koop, N. and Brinkmann, R. and Tungler, A. and Wirbelauer, C. and Birngruber, R. and Laqua, H.: Continuous-wave diode laser thermokeratoplasty: first clinical experience in blind human eyes. J Cataract Refract Surg, no. 25, pp. 32-40, 1999
    BibTeX
    @article{Geerling1999,
       author = {Geerling, G. and Koop, N. and Brinkmann, R. and Tungler, A. and Wirbelauer, C. and Birngruber, R. and Laqua, H.},
       title = {Continuous-wave diode laser thermokeratoplasty: first clinical experience in blind human eyes},
       journal = {J Cataract Refract Surg},
       volume = {25},
       number = {1},
       pages = {32-40},
       note = {0886-3350 (Print)
    Clinical Trial
    Journal Article
    Research Support, Non-U.S. Gov't},
       abstract = {PURPOSE: To evaluate the safety and stability of laser thermokeratoplasty (LTK) with a continuous-wave diode laser in blind human eyes and to optimize parameters for a study in sighted eyes. SETTING: Department of Ophthalmology, Medical University Lubeck, Germany. METHODS: A continuous-wave diode laser was set to emit radiation with a wavelength of 1.854 microns (Group 1, n = 4) or 1.870 microns (Group 2, n = 4) and 100 to 150 mW power for 10 seconds. A focusing handpiece was coupled with an application mask and fixed by partial vacuum to the conjunctiva or cornea. The radiation was focused into the corneal stroma between 400 and 600 microns in Group 1 and set to 1000 microns in Group 2. Eight (Group 1, single ring) or 16 (Group 2, double ring) coagulations were applied. RESULTS: The refractive change increased with higher laser power and smaller ring diameters. Two rings of coagulations provided higher and more stable refractive changes of up to 5.66 diopters (D) than a single ring. The refractive effect stabilized between 3 and 6 months postoperatively. At 1 year, mean refractive change was +0.99 D +/- 0.39 (SD) in Group 1 and +2.32 +/- 2.24 D in Group 2. Extensive endothelial damage occurred in Group 1 but was minimal in Group 2. CONCLUSIONS: Diode LTK was used to treat hyperopia safely and effectively. Regression occurred mainly in the first 3 postoperative months. With a wavelength of 1.870 microns, corneal endothelial damage was limited.},
       keywords = {Adult
    Aged
    Aged, 80 and over
    Blindness/*complications
    Corneal Stroma/pathology/physiopathology/*surgery
    Corneal Topography
    Female
    Humans
    Hyperopia/pathology/physiopathology/*surgery
    Laser Coagulation/adverse effects/*methods
    Male
    Middle Aged
    Postoperative Complications
    Safety},
       url = {http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Citation&list_uids=9888074},
       year = {1999},
       type = {Journal Article}
    }
    

1998

  • Eichenauer, Rolf H. and Huettmann, Gereon and Woermer, Stephan and Koop, Norbert and Beyer, Wolfgang and Jocham, Dieter: New balloon catheter system used for PDT in the human urinary bladder: accuracy of light distribution. pp. 138-144, 1998
    BibTeX
    @article{Eichenauer,
       author = {Eichenauer, Rolf H. and Huettmann, Gereon and Woermer, Stephan and Koop, Norbert and Beyer, Wolfgang and Jocham, Dieter},
       title = {New balloon catheter system used for PDT in the human urinary bladder: accuracy of light distribution},
       pages = {138-144},
       note = {10.1117/12.308141},
       abstract = {Photodynamic therapy (PDT) may provide a new approach for treatment of patients with superficial transitional carcinoma and carcinoma in situ of the bladder. The light applicator for the bladder wall (Rusch) is constructed as a balloon catheter with two concentric balloons. A new PDT applicator (Rusch) was assessed for the homogeneity and accuracy of irradiation during PDT. In an in-vitro experiment with 17 freshly harvested porcine bladders the fluence rate was measured locally with isotropic detectors. The results were compared to the light fluence detected by the PDT applicator. The increase of the fluence rate (beta) inside the bladders due to back scattering ranged between 5.3 and 7.0 with an average of 6.2. Local variations of the fluence rate in the spherical bladders were also smaller than 15%. Therefore it is concluded, that a homogeneous and accurate irradiation during PDT is possible. Blood between the outer balloon and the bladder wall reduces the local fluence rate strongly and should to be avoided. Also larger air bubbles in the applicator can lead to an inhomogeneous light distribution. In regular application the presented new catheter system provides accurate and easy light dosimetry during PDT of the bladder. Attention had to be paid to a continuous flushing of the space between balloon and bladder wall in order to prevent the accumulation of urine and blood. To avoid a malfunction of the system and large errors in light dosimetry and application, it is advisable to monitor the measured light dosage and the shape of the balloon using ultrasonography during PDT.},
       year = {1998}
    }
    
  • Brinkmann, R and Koop, N. and Kamm, K. and Geerling, G. and Kampmeier, J. and Birngruber, R.: Laser Thermokeratoplastik: eine in vitro- und in vivo-Studie mit kontinuierlich emittierender Laserdiode im mittleren IR-Spektralbereich.. Laser in der Medizin, Proc. Laser 97, pp. 412-416, 1998
    BibTeX
    @article{Brinkmann1998,
       author = {Brinkmann, R and Koop, N. and Kamm, K. and Geerling, G. and Kampmeier, J. and Birngruber, R.},
       title = {Laser Thermokeratoplastik: eine in vitro- und in vivo-Studie mit kontinuierlich emittierender Laserdiode im mittleren IR-Spektralbereich.},
       journal = {Laser in der Medizin, Proc. Laser 97},
       pages = {412-416},
       year = {1998},
       type = {Journal Article}
    }
    

1997

  • Koop, Norbert and Langholz, Michael and Birngruber, Reginald and Geerling, Gerd and Bastian, Gerd-Otto: Vergleichende Untersuchungen verschiedener kornealer Topographiemeßgeräte. Der Ophthalmologe, no. 94, pp. 120-126, 1997
    BibTeX Link
    @article{Koop1997,
       author = {Koop, Norbert and Langholz, Michael and Birngruber, Reginald and Geerling, Gerd and Bastian, Gerd-Otto},
       title = {Vergleichende Untersuchungen verschiedener kornealer Topographiemeßgeräte},
       journal = {Der Ophthalmologe},
       volume = {94},
       number = {2},
       pages = {120-126},
       ISSN = {1433-0423},
       url = {http://dx.doi.org/10.1007/s003470050092},
       year = {1997},
       type = {Journal Article}
    }
    
  • Koop, Norbert and Brinkmann, Ralf and Lankenau, Eva and Flache, Stefan and Engelhardt, Ralf and Birngruber, Reginald: Optische Kohärenztomographie der Kornea und des vorderen Augenabschnitts. Der Ophthalmologe, no. 94, pp. 481-486, 1997
    BibTeX Link
    @article{Koop1997,
       author = {Koop, Norbert and Brinkmann, Ralf and Lankenau, Eva and Flache, Stefan and Engelhardt, Ralf and Birngruber, Reginald},
       title = {Optische Kohärenztomographie der Kornea und des vorderen Augenabschnitts},
       journal = {Der Ophthalmologe},
       volume = {94},
       number = {7},
       pages = {481-486},
       ISSN = {1433-0423},
       url = {http://dx.doi.org/10.1007/s003470050143},
       year = {1997},
       type = {Journal Article}
    }
    
  • Koop, N. and Brinkmann, R. and Lankenau, E. and Flache, S. and Engelhardt, R. and Birngruber, R.: Optical coherence tomography of cornea and anterior segment of the eye. Ophthalmologe, no. 94, pp. 481-486, 1997
    BibTeX Link
    @article{Koop1997,
       author = {Koop, N. and Brinkmann, R. and Lankenau, E. and Flache, S. and Engelhardt, R. and Birngruber, R.},
       title = {Optical coherence tomography of cornea and anterior segment of the eye},
       journal = {Ophthalmologe},
       volume = {94},
       number = {7},
       pages = {481-486},
       note = {Yp140
    Times Cited:34
    Cited References Count:19},
       abstract = {Target: The method of optical coherence tomography (OCT) was investigated regarding its suitability and limits for measuring the cornea and the anterior segment of the eye. Furthermore, the stromal expansion of thermally induced lesions in the cornea directly after irradiation was determined within the scope of the laser thermokeratoplasty (LTK).
    Material and methods: With the experimental scanning OCT system, x-z sections of the anterior eye segment were made with an optical resolution of about 20 mu m axially and 25 mu m laterally. Freshly enucleated, tonicized porcine eyes were used as model eyes. Thermal lesions were applied with a continuously emitting laser diode (lambda=1.86 mu m) and various radiation parameters, Before and after coagulation, the cornea was viewed from limbus to limbus in a central OCT scan and the individual coagulation source was measured,
    Results: Global and local changes of the thickness of the cornea as well as the distance between cornea and lens were measured with high precision. Thermal lesions in their expansion can be clearly presented and matching well with the histologically stained sections, bur are not as exactly defined at the edges due to the limited optical resolution, as known from histological preparations.
    Conclusion: With the OCT method quantitative measuring of the anterior eye segment can be performed in vitro and with reduced resolutions also in vivo. Due to the qualitatively good correspondence regarding the dimensions of thermal damage of the cornea with histologically obtained morphometric results,this method can be used for supervision of coagulation directly after LTK as well as for examination of the individual healing process.},
       keywords = {optical coherence tomography
    pachometry
    laser thermokeratoplasty
    thermal damage
    tissue},
       ISSN = {0941-293X},
       DOI = {DOI 10.1007/s003470050143},
       url = {<Go to ISI>://WOS:000071246700003},
       year = {1997},
       type = {Journal Article}
    }
    
  • Asiyo-Vogel, M. N. and Koop, N. and Brinkmann, R. and Engelhardt, R. and Eggers, R. and Birngruber, R. and Vogel, A.: Evaluation of LTK lesions by optical low coherence tomography (OCT) and polarization microscopy after Sirius-Red staining. Ophthalmologe, no. 94, pp. 487-491, 1997
    BibTeX Link
    @article{Asiyo-Vogel1997,
       author = {Asiyo-Vogel, M. N. and Koop, N. and Brinkmann, R. and Engelhardt, R. and Eggers, R. and Birngruber, R. and Vogel, A.},
       title = {Evaluation of LTK lesions by optical low coherence tomography (OCT) and polarization microscopy after Sirius-Red staining},
       journal = {Ophthalmologe},
       volume = {94},
       number = {7},
       pages = {487-491},
       note = {Yp140
    Times Cited:5
    Cited References Count:21},
       abstract = {Background: Information on the extent and degree of the thermal effect produced is of great importance for control of the laser dosage in laser thermokeratoplasty (LTK) and for postoperative follow-up. We investigated on acute LTK effects which information images obtained by optical low coherence tomography (OCT) offer compared to those obtained by polarization microscopy.
    Methods: Porcine eyes were irradiated through a 400 mu m quartz fiber using light from a laser diode emitting up to 300 mW at a wavelength of 1.86 mu m. Thermal lesions of varying strength were scanned using an experimental OCT device with about 25 mu m lateral and 20 mu m axial resolution. Histologic evaluation of the scanned areas was done by polarization microscopy after Sirius-Red staining, and similar lesions were also analyzed by TEM.
    Results: Both methods differentiated three damage zones: a transition zone, a zone of moderate coagulation, and a central zone of strong coagulation. In the transition zone,increased birefringence was seen in polarization microscopy, which correlated with increased light scattering seen in the DCT images,ln the moderately coagulated zone, a decrease in birefringence was associated with an even stronger increase of the OCT signal, In the central zone,a loss of the fibrillar tissue structure was observed, which led to a complete loss of birefringence and a strong reduction of the OCT signal.
    Conclusions: Although OCT does not provide the detailed information on thermal changes of tissue seen by the histologic method, it offers information on the extent and degree of tissue changes without preparation artifacts and provides a non-invasive method of immediate and follow-up control of LTK lesions, A quantitative analysis of changes in corneal thickness and curvature is much simpler than by a slit lamp. Time-resolved measurements of corneal light scattering may be used for on-line control of the laser-light dosage during LTK.},
       keywords = {refractive surgery
    laser thermokeratoplasty
    collagen denaturation
    collagen shrinkage
    optical low coherence tomography
    polarization microscopy
    sirius-red staining
    tissue
    collagen
    eye},
       ISSN = {0941-293X},
       DOI = {DOI 10.1007/s003470050144},
       url = {<Go to ISI>://WOS:000071246700004},
       year = {1997},
       type = {Journal Article}
    }
    
  • Geerling, G. and Brinkmann, R. and Koop, N. and Wirbelauer, C. and Laqua, H. and Birngruber, R.: Diode-laser thermokeratoplasty - First clinical experiences in human blind eyes. Investigative Ophthalmology & Visual Science, no. 38, pp. 2292-2292, 1997
    BibTeX
    @article{Geerling1997,
       author = {Geerling, G. and Brinkmann, R. and Koop, N. and Wirbelauer, C. and Laqua, H. and Birngruber, R.},
       title = {Diode-laser thermokeratoplasty - First clinical experiences in human blind eyes},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {38},
       number = {4},
       pages = {2292-2292},
       note = {1
    Wn186
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1997WN18602285},
       year = {1997},
       type = {Journal Article}
    }
    
  • Asiyo-Vogel, M and Koop, N and Brinkmann, R and Engelhardt, R and Eggers, R and Birngruber, R and Vogel, A: Darstellung von LTK-Läsionen durch optische Kurzkohärenztomographie (OCT) und Polarisationsmikroskopie nach Sirius-Rot-Färbung. Ophthalmologe, no. 94, pp. 487-491, 1997
    BibTeX
    @article{Asiyo-Vogel1997,
       author = {Asiyo-Vogel, M and Koop, N and Brinkmann, R and Engelhardt, R and Eggers, R and Birngruber, R and Vogel, A},
       title = {Darstellung von LTK-Läsionen durch optische Kurzkohärenztomographie (OCT) und Polarisationsmikroskopie nach Sirius-Rot-Färbung},
       journal = {Ophthalmologe},
       volume = {94},
       pages = {487-491},
       year = {1997}
    }
    
  • Brinkmann, R. and Koop, N. and Kampmeier, J. and Bruhns, A. and AsiyoVogel, M. and Engelhardt, R. and Birngruber, R.: Corneal collagen denaturation in laser thermokeratoplasty (LTK). Investigative Ophthalmology & Visual Science, no. 38, pp. 2514-2514, 1997
    BibTeX
    @article{Brinkmann1997,
       author = {Brinkmann, R. and Koop, N. and Kampmeier, J. and Bruhns, A. and AsiyoVogel, M. and Engelhardt, R. and Birngruber, R.},
       title = {Corneal collagen denaturation in laser thermokeratoplasty (LTK)},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {38},
       number = {4},
       pages = {2514-2514},
       note = {1
    Wn186
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1997WN18602506},
       year = {1997},
       type = {Journal Article}
    }
    
  • Koop, N. and Langholz, M. and Birngruber, R. and Geerling, G. and Bastian, G. O.: Comparative evaluation of different corneal topographical devices. Ophthalmologe, no. 94, pp. 120-126, 1997
    BibTeX Link
    @article{Koop1997
       author = {Koop, N. and Langholz, M. and Birngruber, R. and Geerling, G. and Bastian, G. O.},
       title = {Comparative evaluation of different corneal topographical devices},
       journal = {Ophthalmologe},
       volume = {94},
       number = {2},
       pages = {120-126},
       note = {Yp129
    Times Cited:0
    Cited References Count:25},
       abstract = {Purpose: It is difficult to measure the topography of the cornea with high resolution and visualize it on a map displaying refraction. This is demonstrated by the ongoing improvement and further development of different methods and by the fact that users of these techniques are not always satisfied.
    Materials and methods: Five different ring projectors were compared. Spherical and aspherical ball standards were used to measure the standard deviation of the refraction of the system. A patient group of eight people with healthy eyes was used to compare the measurement accuracy and operational errors. Some patients were also measured after cataract surgery. The lateral and axial range of the devices was determined.
    Results: The measurement accuracy for bail stand ards for the five devices was below 1/8 D. For the in vivo case in the control group it was below 1/4 D for four devices. Furthermore, the reproducibility of the results, the accuracy of angle determination and the influence of mechanical and optical design will be discussed. The study demonstrates applications and limits of this measurement method.},
       keywords = {placido-disk
    corneal topography
    refractive power
    videokeratoscope
    accuracy
    system
    reproducibility},
       ISSN = {0941-293X},
       DOI = {DOI 10.1007/s003470050092},
       url = {<Go to ISI>://WOS:000071245600008},
       year = {1997},
       type = {Journal Article}
    }
    
  • Wirbelauer, C. and Geerling, G. and Koop, N. and Brinkmann, R. and Tungler, A. and Birngruber, R. and Laqua, H.: Acute endothelial cell changes after laser thermal keratoplasty with a CW-IR laser diode. Investigative Ophthalmology & Visual Science, no. 38, pp. 2516-2516, 1997
    BibTeX
    @article{Wirbelauer1997,
       author = {Wirbelauer, C. and Geerling, G. and Koop, N. and Brinkmann, R. and Tungler, A. and Birngruber, R. and Laqua, H.},
       title = {Acute endothelial cell changes after laser thermal keratoplasty with a CW-IR laser diode},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {38},
       number = {4},
       pages = {2516-2516},
       note = {1
    Wn186
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1997WN18602508},
       year = {1997},
       type = {Journal Article}
    }
    

1996

  • Wetzel, W. and Brinkmann, R. and Koop, N. and Schroer, F. and Birngruber, R.: Photofragmentation of lens nuclei using the Er:YAG laser: Preliminary report of an in vitro study. German Journal of Ophthalmology, no. 5, pp. 281-284, 1996
    BibTeX Link
    @article{Wetzel1996,
       author = {Wetzel, W. and Brinkmann, R. and Koop, N. and Schroer, F. and Birngruber, R.},
       title = {Photofragmentation of lens nuclei using the Er:YAG laser: Preliminary report of an in vitro study},
       journal = {German Journal of Ophthalmology},
       volume = {5},
       number = {5},
       pages = {281-284},
       note = {Vq341
    Times Cited:13
    Cited References Count:12},
       abstract = {The energy of the erbium:YAG laser (2,940-nm wave-length) can be used for minimally traumatic photoablation due to its high absorption at the tissue water and its consequently low penetration depth. Laser sclerostomy ab externo, an application of this principle, has undergone advanced clinical investigation. Another potential application is photofragmentation of the lens for cataract extraction. A laboratory model Er: YAG laser (flashlamp-pumped, 200-mu s pulse length, 5-Hz repetition frequency) was coupled to a short low-OH quartz fiber (400 mu m in diameter). The laser energy was applied by direct contact of the fiber tip to human lenses with very dense cataract. The lenses rested in a small cuvette filled with an aqueous-humor-analogous fluid. The fragmentablation rate was evaluated in relation to the number of pulses and the pulse energy. A laser-triggered flash-photography unit was engaged to visualize the ablation dynamics. We found tissue-ablation rates to range from 4 to 19 mu g/pulse, depending on the nucleus density and ulse energy. The maximal size of the removed fragments was always below 500 mu m During ablation, rapidly increasing and collapsing cavitation bubbles were photographed at the distal tip of the application fiber. The impact radius of these cavitation effects markedly exceeded the pure penetration depth of laser radiation at a 2.9-mu m wavelength. A clinical application of the method should be possible as judged by the results obtained for tissue-ablation rate and fragment size. Cavitation-bubble dynamics seems to be responsible for the high fragmentation efficiency. Special application probes have to be developed to optimize ablation and to prevent inadvertent destruction of the posterior lens capsule by cavitation effects.},
       keywords = {phacoemulsification
    er:yag laser
    cavitation effects
    ablation
    surgery},
       ISSN = {0941-2921},
       url = {<Go to ISI>://WOS:A1996VQ34100006},
       year = {1996},
       type = {Journal Article}
    }
    
  • Gerling, G. and Vogel, A. and ElHifnawi, E. and Koop, N. and Droge, G. and Birngruber, R. and Brinkmann, R.: Morphological and biomorphometrical observations on laser thermal keratoplasty - Histological and biomorphometrical examination of the relationship between refractive change and the volume of laser thermal keratoplasty lesions following Cr:Tm:Ho:YAG laser treatment. German Journal of Ophthalmology, no. 5, pp. 84-91, 1996
    BibTeX
    @article{Gerling1996,
       author = {Gerling, G. and Vogel, A. and ElHifnawi, E. and Koop, N. and Droge, G. and Birngruber, R. and Brinkmann, R.},
       title = {Morphological and biomorphometrical observations on laser thermal keratoplasty - Histological and biomorphometrical examination of the relationship between refractive change and the volume of laser thermal keratoplasty lesions following Cr:Tm:Ho:YAG laser treatment},
       journal = {German Journal of Ophthalmology},
       volume = {5},
       number = {2},
       pages = {84-91},
       note = {Vf915
    Times Cited:4
    Cited References Count:21},
       abstract = {Laser thermal keratoplasty (LTK) is currently under clinical trial for the correction of hyperopia and hyperopic astigmatism by means of collagen coagulation in the peripheral cornea. The purpose of our study was to optimize the ratio between the volume of damaged corneal stroma and the refractive effect so as to minimize potential side effects such as endothelial damage or induction of glare phenomena. We therefore performed histological and morphometrical examinations of enucleated pig eyes to determine the relationship between the coagulated stromal volume and the refractive change after LTK using a pulsed Cr: Tm: Ho: YAG laser (wavelength 2.12 mu m) on enucleated pig eyes. The refractive change was documented with a Littman ophthalmometer. Morphometrical analysis was performed using polarized light microscopy of sirius red-stained specimens. This special stain separated the thermally changed stroma into a dark, nonbirefringent center and a birefringent peripheral zone. The volume of both zones was positively correlated with the refractive change induced. The volume was in turn influenced by the choice of laser parameters, From the ratio of the volume to the refractive change it was found that pulse energies above 30 mJ led to an enlargement of the coagulation volume without increasing the refractive change effectively. The use of high pulse energies did not improve the effect of LTK but only increased the risk of unwanted side effects. However, an increase in the laser repetition rate at a constant pulse number per spot led to refractive changes with a minimal coagulation volume. The highest relative refractive change was achieved with a dark central zone and a birefringent zone, each having a volume of about 50 - 80 x 10(-3) mm(3).},
       keywords = {laser thermal keratoplasty
    hyperopic correction
    biomorphometry
    sirius red stain
    polarization microscopy
    organization
    microscopy
    collagen},
       ISSN = {0941-2921},
       url = {<Go to ISI>://WOS:A1996VF91500004},
       year = {1996},
       type = {Journal Article}
    }
    
  • Brinkmann, R. and Koop, N. and Kamm, K. and Geerling, G. and Kampmeier, J. and Birngruber, R.: Laser thermokeratoplasty: an in vitro and in vivo-study by means of a Continous Wave Mid-IR laser diode.. Lasermedizin, no. 12, pp. 179-186, 1996
    BibTeX
    @article{Brinkmann1996,
       author = {Brinkmann, R. and Koop, N. and Kamm, K. and Geerling, G. and Kampmeier, J. and Birngruber, R.},
       title = {Laser thermokeratoplasty: an in vitro and in vivo-study by means of a Continous Wave Mid-IR laser diode.},
       journal = {Lasermedizin},
       volume = {12},
       pages = {179-186},
       year = {1996},
       type = {Journal Article}
    }
    
  • Geerling, G. and Brinkmann, R. and Koop, N. and Klingemann, I. and Laqua, H. and Birngruber, R.: Laser thermokeratoplasty - Experimental study in minipigs with a cw-IR laser diode. Investigative Ophthalmology & Visual Science, no. 37, pp. 304-304, 1996
    BibTeX
    @article{Geerling1996,
       author = {Geerling, G. and Brinkmann, R. and Koop, N. and Klingemann, I. and Laqua, H. and Birngruber, R.},
       title = {Laser thermokeratoplasty - Experimental study in minipigs with a cw-IR laser diode},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {37},
       number = {3},
       pages = {304-304},
       note = {Tx397
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1996TX39700304},
       year = {1996},
       type = {Journal Article}
    }
    
  • Brinkmann, R. and Koop, N. and AsiyoVogel, M. N. and Kaftan, B. and Birngruber, R. and Engelhardt, R.: CW-IR laser thermokeratoplasty: Refractive changes and analysis by optical coherence tomography and light microscopy. Investigative Ophthalmology & Visual Science, no. 37, pp. 305-305, 1996
    BibTeX
    @article{Brinkmann1996,
       author = {Brinkmann, R. and Koop, N. and AsiyoVogel, M. N. and Kaftan, B. and Birngruber, R. and Engelhardt, R.},
       title = {CW-IR laser thermokeratoplasty: Refractive changes and analysis by optical coherence tomography and light microscopy},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {37},
       number = {3},
       pages = {305-305},
       note = {Tx397
    Times Cited:0
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1996TX39700305},
       year = {1996},
       type = {Journal Article}
    }
    

1995

  • Schirner, G. and Koop, N. and Elhifnawi, E. and Birngruber, R. and Brinkmann, R.: Experiments with Pulsed and Continuous-Wave Laser Sources to Optimize Laserthermo-Keratoplasty. Vision Research, no. 35, pp. P167-P167, 1995
    BibTeX Link
    @article{Schirner1995,
       author = {Schirner, G. and Koop, N. and Elhifnawi, E. and Birngruber, R. and Brinkmann, R.},
       title = {Experiments with Pulsed and Continuous-Wave Laser Sources to Optimize Laserthermo-Keratoplasty},
       journal = {Vision Research},
       volume = {35},
       pages = {P167-P167},
       note = {Suppl. S
    Rz562
    Times Cited:0
    Cited References Count:0},
       ISSN = {0042-6989},
       url = {<Go to ISI>://WOS:A1995RZ56200472},
       year = {1995},
       type = {Journal Article}
    }
    
  • Schirner, G. and Brinkmann, R. and Droge, G. and Koop, N. and Elhifnawi, E. S. and Birngruber, R.: Experimental Studies to Optimize Laser-Thermokeratoplasty Using Pulsed and Cw-Laser-Sources. Investigative Ophthalmology & Visual Science, no. 36, pp. S716-S716, 1995
    BibTeX Link
    @article{Schirner1995,
       author = {Schirner, G. and Brinkmann, R. and Droge, G. and Koop, N. and Elhifnawi, E. S. and Birngruber, R.},
       title = {Experimental Studies to Optimize Laser-Thermokeratoplasty Using Pulsed and Cw-Laser-Sources},
       journal = {Investigative Ophthalmology & Visual Science},
       volume = {36},
       number = {4},
       pages = {S716-S716},
       note = {Qm915
    Times Cited:3
    Cited References Count:0},
       ISSN = {0146-0404},
       url = {<Go to ISI>://WOS:A1995QM91503294},
       year = {1995},
       type = {Journal Article}
    }
    

1994

  • Brinkmann, R. and Dröge, G. and Koop, N. and Wördemann, A. and Schirner, G. and Birngruber, R.: Investigations on laser thermokeratoplasty. Lasers Light Ophthalmol, no. 6, pp. 259 - 270, 1994
    BibTeX
    @article{Binkmann1994,
       author = {Brinkmann, R. and Dröge, G. and Koop, N. and Wördemann, A. and Schirner, G. and Birngruber, R.},
       title = {Investigations on laser thermokeratoplasty},
       journal = {Lasers Light Ophthalmol},
       volume = {6},
       number = {4},
       pages = {259 - 270},
       year = {1994},
       type = {Journal Article}
    }
    

1989

  • Ulrich, H. and Wijnaendts-van-Resandt, R. W. and Koop, N. and Schickfuss, M. v and Rensch, C. and Ehrensperger, W.: Quality of microstructures produced by laser lithography and system performance. Microelectronic Engineering, no. 9, pp. 69-72, 1989
    BibTeX Link
    @article{Koop1989,
       author = {Ulrich, H. and Wijnaendts-van-Resandt, R. W. and Koop, N. and Schickfuss, M. v and Rensch, C. and Ehrensperger, W.},
       title = {Quality of microstructures produced by laser lithography and system performance},
       journal = {Microelectronic Engineering},
       volume = {9},
       number = {1},
       pages = {69-72},
       ISSN = {0167-9317},
       url = {http://www.sciencedirect.com/science/article/pii/0167931789900154},
       year = {1989},
       type = {Journal Article}
    }
    

  • Brinkmann, R. and Koop, N. and Ozdemir, M. and Alt, C. and Schule, G. and Lin, C. P. and Birngruber, R.: Targeting of the retinal pigment epithelium (RPE) by means of a rapidly scanned continuous wave (CW) laser beam. Lasers Surg Med, no. 32, pp. 252-64,
    BibTeX
    @article{Brinkmann2003,
       author = {Brinkmann, R. and Koop, N. and Ozdemir, M. and Alt, C. and Schule, G. and Lin, C. P. and Birngruber, R.},
       title = {Targeting of the retinal pigment epithelium (RPE) by means of a rapidly scanned continuous wave (CW) laser beam},
       journal = {Lasers Surg Med},
       volume = {32},
       number = {4},
       pages = {252-64},
       note = {0196-8092 (Print)
    In Vitro
    
  • Qu, Xiaochao and Norbert, Koop and Li, Zheng and Wang, Jing and Zhang, Zhenxi and Hüttmann, Gereon: Multiphoton fluorescence lifetime imaging of Karpas 299 cells using ACT1 antibody conjugated gold nanoparticles. no. 6630, pp. 66301C-66301C-8,
    BibTeX Link
    @inproceedings{Qu2007,
       author = {Qu, Xiaochao and Norbert, Koop and Li, Zheng and Wang, Jing and Zhang, Zhenxi and Hüttmann, Gereon},
       title = {Multiphoton fluorescence lifetime imaging of Karpas 299 cells using ACT1 antibody conjugated gold nanoparticles},
       volume = {6630},
       pages = {66301C-66301C-8},
       note = {10.1117/12.728239},
       abstract = {Due to the unique optical properties, gold nanoparticles (NPs) can play a useful role in biological cellular imaging as biological probes. Using multiphoton microscopy and fluorescence lifetime imaging (FLIM) system, we recorded the images of Karpas 299 cells incubated without, or with gold NPs, and ACT1 antibodies conjugated with gold NPs. From the FLIM, we can easily discriminate the difference among different experiment conditions due to the distinct lifetime between cells and gold NPs. Our results present that nonconjugated gold NPs are accumulated inside cells, but conjugated gold NPs bind homogeneously and specifically to the surface of cancer cells. For single Karpas 299 cells, the signal is very week when the excitation power is about 10mw; while the power is approximately 28 mw, a very sharp cell imaging can be obtained. For the Karpas 299 incubated with ACT1 conjugated gold NPs, while the excitation power is 10mw, gold NPs have clear fluorescence signal so that the profile of cells can be detected; Signal of gold NPs is very strong when the power arrived in 20mw. These results suggest that the multiphoton lifetime imaging of antibody conjugated gold NPs can support a useful method in diagnosis of cancer.},
       url = {http://dx.doi.org/10.1117/12.728239},
       type = {Conference Proceedings}
    }
    
  • Brinkmann, Ralf and Kampmeier, Juergen and Grotehusmann, Ulf and Vogel, Alfred and Koop, Norbert and Asiyo-Vogel, Mary and Birngruber, Reginald: Corneal collagen denaturation in laser thermokeratoplasty. no. 2681, pp. 56-63,
    BibTeX Link
    @inproceedings{Brinkmann1996,
       author = {Brinkmann, Ralf and Kampmeier, Juergen and Grotehusmann, Ulf and Vogel, Alfred and Koop, Norbert and Asiyo-Vogel, Mary and Birngruber, Reginald},
       title = {Corneal collagen denaturation in laser thermokeratoplasty},
       volume = {2681},
       pages = {56-63},
       note = {10.1117/12.239611},
       abstract = {In laserthermokeratoplasty (LTK) thermal denaturation and shrinkage of corneal collagen is used to correct hyperopia and astigmatism. In order to optimize dosimetry, the temperature at which maximal shrinkage of collagen fibrils occurs is of major interest. Since the exposure time in clinical LTK-treatment is limited to a few seconds, the kinetics of collagen denaturation as a rate process has to be considered, thus the time of exposure is of critical importance for threshold and shrinkage temperatures. We investigated the time-temperature correlation for corneal collagen denaturation within different time domains by turbidimetry of scattered HeNe laser probe light using a temperature controlled water bath and pulsed IR laser irradiation. In the temperature range of 60 degree(s)C to 95 degree(s)C we found an exponential relation between the denaturation time and temperature. For the typical LTK-treatment time of 2 s, a temperature of 95 degree(s)C is needed to induce thermal damage. Use of pulsed Holmium laser radiation gave significant scattering of HeNe laser probe light at calculated temperatures of around 100 degree(s)DC. Rate parameters according to the formalism of Arrhenius were fitted to these results. Force measurements showed the simultaneous onset of light scattering and collagen shrinkage.},
       url = {http://dx.doi.org/10.1117/12.239611},
       type = {Conference Proceedings}
    }
    
  • Steven, Philip and Koop, Norbert and Huttmann, Gereon: Confocal microscopy versus two-photon microscopy: imaging of ocular surface pathologies. no. 6860, pp. 686023, SPIE,
    BibTeX
    @inproceedings{Steven,
       author = {Steven, Philip and Koop, Norbert and Huttmann, Gereon},
       title = {Confocal microscopy versus two-photon microscopy: imaging of ocular surface pathologies},
       editor = {Ammasi, Periasamy and Peter, T. C. So},
       publisher = {SPIE},
       volume = {6860},
       pages = {686023},
    
    }
  • Miura, Y and Huettmann, G and Orzekowsky-Schroeder, R and Steven, P and Szaszák, M and Koop, N and Brinkmann, R: Appearance of autofluorescence in RPE cells at the rim of photocoagulation. in FLIM 2010 - Symposium Fluorescence Lifetime Imaging of the Human Retina,
    BibTeX
    @inproceedings{Miura2010,
       author = {Miura, Y and Huettmann, G and Orzekowsky-Schroeder, R and Steven, P and Szaszák, M and Koop, N and Brinkmann, R},
       title = {Appearance of autofluorescence in RPE cells at the rim of photocoagulation},
       booktitle = {FLIM 2010 - Symposium "Fluorescence Lifetime Imaging of the Human Retina"},
       type = {Conference Proceedings}
    }