@article{Koop2020,
   author = {Koop, N},
   title = {Beständig durch Mikrodefekte},
   journal = {Pharma+Food},
   url = { https://www.pharma-food.de/bestaendig-durch-mikrodefekte/},
   year = {2020},
   type = {Journal Article}
}

@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}
}

title = {Non-Invasive Multi-Dimensional Two-Photon Microscopy enables optical fingerprinting (TPOF) of immune cells},
journal = {Journal of Biophotonics},
volume = {8},
number = {6},
pages = {466-479},
keywords = {ocular surface, intravital two-photon microscopy, antigen presenting cells, in vivo, non invasive},
doi = {https://doi.org/10.1002/jbio.201400036},
url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.201400036},
eprint = {https://onlinelibrary.wiley.com/doi/pdf/10.1002/jbio.201400036},
abstract = {Mucosal surfaces are constantly exposed to pathogens and show high immunological activity. In a broad variety of ocular surface disorders inflammation is common, but underlying mechanisms are often not fully understood. However, the main clinical problem is that inflammatory processes are difficult to characterize and quantify due to the impossibility of repeated tissue probing of the delicate ocular surface. Therefore non-invasive optical methods are thought to have the potential for intravital investigation of ocular surface inflammation. This study demonstrates the general potential of two-photon microscopy to non-invasively detect and discriminate key players of inflammation in the ocular surface by using intrinsic fluorescence-based features without the necessity of tissue probing or the use of dyes. The use of wavelength dependent measurements of fluorescence lifetime, in addition to autofluorescence intensity enables a functional differentiation of isolated immune cells in vitro at excitation wavelengths between 710 to 830 nm. Mixed cell cultures and first in vivo results indicate the use of excitation wavelength of 710 to 750 nm for further experiments and future use in patients. Two photon based autofluorescence features of immune cells enables non-invasive differentiation.},
year = {2015}
}

@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}
}

@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}
}

@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}
}

@article{Klinder2012,
   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}
}

@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}
}

@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},
Year = { 2010}
}

@article{Steven-2009,
   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}
}

@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}
}

@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}
}

@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}
}

@article{Steven2008,
   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}
}

@inproceedings{Steven-2008,
   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},
year = { 2008}
}

@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}
}

@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}
}

@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},
year = { 2007}
}

@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(4)},
  year = { 2003},
url = { https://onlinelibrary.wiley.com/doi/abs/10.1002/lsm.10150},
   pages = {252-64},
   note = {0196-8092 (Print)}
}

@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}
}

@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}
}

@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},
url = {https://www.scopus.com/record/display.uri?eid=2-s2.0-0034040252&origin=inward&txGid=6e537773e3e3f14b9b83f939c4a9ce7d},
   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}
}

@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(5)},
   Year = {2000},
   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}
}

@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}
}

@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}
}