Yoko
Miura,
Regina
Orzekowsky-Schröder,
Philipp
Steven,
Márta
Szaszák,
Norbert
Koop, and
Ralf
Brinkmann,
Two-Photon Microscopy and Fluorescence Lifetime Imaging of Retinal Pigment Epithelial Cells under Oxidative Stress, Invest Ophthalmol Vis Sci , 2013.
Two-Photon Microscopy and Fluorescence Lifetime Imaging of Retinal Pigment Epithelial Cells under Oxidative Stress, Invest Ophthalmol Vis Sci , 2013.
DOI: | https://doi.org/10.1167/iovs.13-11808 |
Bibtex: | @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} } |
Felix
Treumer,
Alexa
Klettner,
J.
Baltz,
A. A.
Hussain,
Yoko
Miura,
Ralf
Brinkmann,
Johann
Roider, and
Jost
Hillenkamp,
Vectorial release of matrix metalloproteinases (MMPs) from porcine RPE-choroid explants following selective retina therapy (SRT): towards slowing the macular ageing process, Exp Eye Res , vol. 97, no. 1, pp. 63-72, 2012.
Vectorial release of matrix metalloproteinases (MMPs) from porcine RPE-choroid explants following selective retina therapy (SRT): towards slowing the macular ageing process, Exp Eye Res , vol. 97, no. 1, pp. 63-72, 2012.
DOI: | 10.1016/j.exer.2012.02.011 |
Bibtex: | @article{Treumer2012, author = {Treumer, F. and Klettner, A. and Baltz, J. and Hussain, A. A. and Miura, Y. and Brinkmann, R. and Roider, J. and Hillenkamp, J.}, title = {Vectorial release of matrix metalloproteinases (MMPs) from porcine RPE-choroid explants following selective retina therapy (SRT): towards slowing the macular ageing process}, journal = {Exp Eye Res}, volume = {97}, number = {1}, pages = {63-72}, note = {1096-0007 Treumer, F Klettner, A Baltz, J Hussain, A A Miura, Y Brinkmann, R Roider, J Hillenkamp, J Journal Article England Exp Eye Res. 2012 Apr;97(1):63-72. doi: 10.1016/j.exer.2012.02.011. Epub 2012 Feb 22.}, abstract = {The purpose of this study was to investigate release of matrix metalloproteinases (MMP) 2 and 9 during retinal pigment epithelium (RPE) wound healing after Selective Retina Therapy (SRT) with laser energy levels below and above the threshold of RPE cell death. Following exposure to SRT using a prototype pulsed Nd:YLF laser with energies of 80-180 mJ/cm(2) fresh porcine RPE-monolayers with Bruch's membrane and choroid were cultured in modified Ussing chambers which separate the apical (RPE-facing) and basal (choroid facing) sides of the RPE monolayer. Threshold energy for RPE cell death and wound healing were determined with calcein-AM viability test. Inactive and active forms of MMP 2 and 9 were quantified within tissue samples and in the culture medium of the apical and basal compartments of the Ussing chamber using gelatine zymography. Laser energies of 160-180 mJ/cm(2) resulted in cell death within 1 h while 120-140 mJ/cm(2) resulted in delayed death of exposed RPE cells. All cells survived 80 and 100 mJ/cm(2). Laser spots healed within 6 days after SRT accompanied by a transient vectorial increase of MMPs. SRT with 180 mJ/cm(2) increased active MMP 2 by 1.9 (p < 0.05) and 1.6 (p < 0.05) fold in tissue and basal compartments, respectively, without alterations in the apical compartment. Pro-MMP 2 levels were also significantly increased in all compartments (p < 0.05). Release of MMP 9 was not altered. Laser energy below the threshold of RPE cell death did not alter the release of MMP 2 or 9. The findings suggest that the release of active MMP 2 on the basal side of the RPE during wound healing following SRT may address age-related pathological changes of Bruch's membrane with a potential to slow degenerative macular ageing processes before irreversible functional loss has occurred.}, keywords = {Animals Cell Death Cell Survival Choroid/*enzymology/pathology Diffusion Chambers, Culture Fluoresceins/metabolism *Laser Therapy Lasers, Solid-State Macular Degeneration/enzymology/pathology/*surgery Matrix Metalloproteinase 2/*metabolism Matrix Metalloproteinase 9/*metabolism Organ Culture Techniques Retinal Pigment Epithelium/*enzymology/pathology Sensory Thresholds Swine Wound Healing/*physiology}, ISSN = {0014-4835}, DOI = {10.1016/j.exer.2012.02.011}, year = {2012}, type = {Journal Article} } |
Stefan
Koinzer,
Kerstin
Schlott,
Lea
Portz,
Lars
Ptaszynski,
Alexander
Baade,
Marco
Bever,
Mark
Saeger,
Amke
Caliebe,
Renè
Denner,
Ralf
Brinkmann, and
Johann
Roider,
Correlation of temperature rise and optical coherence tomography characteristics in patient retinal photocoagulation, Journal of Biophotonics , pp. n/a-n/a, 2012.
Correlation of temperature rise and optical coherence tomography characteristics in patient retinal photocoagulation, Journal of Biophotonics , pp. n/a-n/a, 2012.
Ingo
Rohde,
Ralf
Brinkmann, and
Dirk
Theisen-Kunde,
Temporally stretched Q-switched pulses in the 2 µm spectral range, Laser Physics Letters , vol. 9, no. 11, pp. 808-813, 2012.
Temporally stretched Q-switched pulses in the 2 µm spectral range, Laser Physics Letters , vol. 9, no. 11, pp. 808-813, 2012.
Ralf
Brinkmann,
Stefan
Koinzer,
Kerstin
Schlott,
Lars
Ptaszynski,
Marco
Bever,
Alexander
Baade,
Susanne
Luft,
Yoko
Miura, and
Johann
Roider,
Real-time temperature determination during retinal photocoagulation on patients, Journal of Biomedical Optics , vol. 17, no. 6, pp. 061219, 2012.
Real-time temperature determination during retinal photocoagulation on patients, Journal of Biomedical Optics , vol. 17, no. 6, pp. 061219, 2012.
DOI: | 10.1117/1.JBO.17.6.061219 |
Bibtex: | @article{Brinkmann2012, author = {Brinkmann, Ralf and Koinzer, Stefan and Schlott, Kerstin and Ptaszynski, Lars and Bever, Marco and Baade, Alexander and Luft, Susanne and Miura, Yoko and Roider, Johann and Birngruber, Reginald}, title = {Real-time temperature determination during retinal photocoagulation on patients}, journal = {Journal of Biomedical Optics}, volume = {17}, number = {6}, pages = {061219}, note = {Journal Article}, year = { 2012} } |
Stefan
Koinzer,
Kerstin
Schlott,
Lars
Ptaszynski,
Marco
Bever,
Susanne
Kleemann,
Mark
Saeger,
Alexander
Baade,
Amke
Caliebe,
Yoko
Miura,
Reginald
Birngruber,
Ralf
Brinkmann, and
Johann
Roider,
Temperature-controlled retinal photocoagulation - a step toward automated laser treatment, Invest Ophthalmol Vis Sci , vol. 53, no. 7, pp. 3605-14, 2012.
Temperature-controlled retinal photocoagulation - a step toward automated laser treatment, Invest Ophthalmol Vis Sci , vol. 53, no. 7, pp. 3605-14, 2012.
DOI: | https://doi.org/10.1167/iovs.11-8588 |
Bibtex: | @article{Koinzer2012, author = {Koinzer, S. and Schlott, K. and Ptaszynski, L. and Bever, M. and Kleemann, S. and Saeger, M. and Baade, A. and Caliebe, A. and Miura, Y. and Birngruber, R. and Brinkmann, R. and Roider, J.}, title = {Temperature-controlled retinal photocoagulation - a step toward automated laser treatment}, journal = {Invest Ophthalmol Vis Sci}, volume = {53}, number = {7}, pages = {3605-14}, note = {Using Smart Source Parsing Jun 14; Print 2012 Jul}, abstract = {Purpose. Retinal laser photocoagulation carries the risk of overtreatment due to effect variation of identically applied lesions. The degree of coagulation depends on the induced temperature increase and on exposure time. We introduce temperature controlled photocoagulation (TCP), which uses optoacoustics to determine individually exposure times necessary to create reproducible lesions. Methods. Optoacoustic temperature measurement relies on pressure waves that are excited in the retinal tissue by repetitive low-energy laser pulses. Signal amplitudes correlate with tissue temperature and are detected by a transducer in the laser contact lens. We used a continuous wave (CW) photocoagulator for treatment irradiation and superimposed probe laser pulses for simultaneous temperature measurement. Optoacoustic data of 1500 lesions (rabbit) were evaluated to develop an algorithm that controls exposure times automatically in TCP. Lesion diameters of 156 TCP lesions were compared to 156 non-controlled lesions. Histology was performed after 1 hour, and 1 and 4 weeks. Results. TCP resulted in exposure times from 4 to 800 ms depending on laser power chosen. Ophthalmoscopic and histologic lesion diameters were independent of power between 14 and 200 mW. TCP lesions barely were visible with a mean diameter equal to the treatment beam (130 mum). In contrast, standard lesion diameters increased linearly and statistically significantly with power. Histology confirmed sparing of the ganglion and nerve fiber layers in TCP. Conclusions. TCP facilitates uniform retinal lesions over a wide power range. In a clinical setting, it should generate soft and reproducible lesions independently of local tissue variation and improve safety, particularly at short exposure times.}, year = {2012} } |
Kerstin
Schlott,
Stefan
Koinzer,
Lars
Ptaszynski,
Marco
Bever,
Johann
Roider, and
Ralf
Brinkmann,
Automatic temperature controlled retinal photocoagulation, Journal of Biomedical Optics , vol. 17, no. 6, pp. 061223, 2012. SPIE.
Automatic temperature controlled retinal photocoagulation, Journal of Biomedical Optics , vol. 17, no. 6, pp. 061223, 2012. SPIE.
DOI: | 10.1117/1.JBO.17.6.061223 |
Datei: | |
Bibtex: | @article{Schlott2012, author = {Schlott, Kerstin and Koinzer, Stefan and Ptaszynski, Lars and Bever, Marco and Baade, Alex and Roider, Johann and Birngruber, Reginald and Brinkmann, Ralf}, title = {Automatic temperature controlled retinal photocoagulation}, journal = {Journal of Biomedical Optics}, volume = {17}, number = {6}, pages = {061223}, keywords = {AutoPhoN}, year = {2012} } |
Kumiko
Yoshimoto,
Manabu
Yamamoto,
Takeya
Kohno,
Tasuku
Yoneda,
Yusaku
Yoshida,
Andreas
Fritz,
Dirk
Theisen-Kunde,
Yoko
Miura,
Ralf
Brinkmann, and
Kunihiko
Shiraki,
Detection Of Sub-threshold Laser Irradiation Spots With Various Fundus Imaging Methods And Its Correlation With Irradiation Energy And Optoacoustic Values In Selective Retina Therapy , Investigative Ophthalmology & Visual Science , vol. 53, pp. 5198, 2012.
Detection Of Sub-threshold Laser Irradiation Spots With Various Fundus Imaging Methods And Its Correlation With Irradiation Energy And Optoacoustic Values In Selective Retina Therapy , Investigative Ophthalmology & Visual Science , vol. 53, pp. 5198, 2012.
Hisashi
Iwami,
Lars
Ptaszynski,
Veit
Danicke,
Ralf
Brinkmann, and
Yoko
Miura,
Sublethal Hyperthermia-induced Vascular Endothelial Growth Factor Secretion And Its Contribution To Adoptive Response Of Retinal Pigment Epithelial Cell, Invest. Ophthalmol. Vis. Sci. , vol. 53, no. 6, pp. 4782-, 2012.
Sublethal Hyperthermia-induced Vascular Endothelial Growth Factor Secretion And Its Contribution To Adoptive Response Of Retinal Pigment Epithelial Cell, Invest. Ophthalmol. Vis. Sci. , vol. 53, no. 6, pp. 4782-, 2012.
Datei: | 4782 |
Bibtex: | @article{Iwami2012, author = {Iwami, Hisashi and Ptaszynski, Lars and Danicke, Veit and Brinkmann, Ralf and Miura, Yoko}, title = {Sublethal Hyperthermia-induced Vascular Endothelial Growth Factor Secretion And Its Contribution To Adoptive Response Of Retinal Pigment Epithelial Cell}, journal = {Invest. Ophthalmol. Vis. Sci.}, volume = {53}, number = {6}, pages = {4782-}, abstract = {PurposeTo investigate temperature increase-induced secretion of vascular endothelial growth factor (VEGF) from retinal pigment epithelial (RPE) cells and its contribution to adoptive response relating to cell defence system against oxidative stress. MethodsPorcine RPE cells on 35 mm culture dish were used in the study. Thulium laser ({lambda}=1940 nm, spot size 33 mm was utilized as a heat source. Temperature increase during irradiation for different power and time setting at cell level was measured with thermocouple, and power and time setting of the experiment was determined based on this calibration. Culture medium was replaced by 1.2 ml phosphate buffer saline and then laser was irradiated with different power settings for 10 seconds, so that the peak temperature reaches from 40{degrees}C to 65{degrees}C. Cellular viability after laser irradiation was examined with MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay immediately after irradiation. VEGF secretion was investigated with enzyme-linked immunosorbent assay (ELISA) at 2 and 24 hrs after irradiation. Contribution of a temperature-dependent calcium channel, TRPV (transient receptor potential vanilloid) channels in laser-induced VEGF secretion was investigated using TRPV channel blocker, ruthenium red (20 {micro}M). TRPV channel blocker-containing medium was replaced by the normal medium soon after laser irradiation. Hydrogen peroxide (H2O2) or advanced glycation endproduct (AGE)-was exposed after 6 hrs of laser irradiation and cell viability was examined with MTT assay. ResultsPeak temperature threshold for immediate RPE cell death was found around 55 {degrees}C with our irradiation setting. VEGF secretion was increased after sub-lethal irradiation in power-dependent manner, which was partially suppressed by TRPV channel blocker. Sublethal laser irradiation reduced H2O2 and AGE-induced cell death and this effect was smaller in the cells treated with TRPV channel inhibitor during laser irradiation. ConclusionsSublethal temperature increase-induced VEGF production might contribute to the enhancement of RPE cell defence system against oxidative stress.}, url = {http://abstracts.iovs.org/cgi/content/abstract/53/6/4782}, year = {2012}, type = {Journal Article} } |
Manabu
Yamamoto,
Takeya
Kohno,
Yusaku
Yoshida,
Tasuku
Yoneda,
Hisashi
Iwami,
Andreas
Fritz,
Dirk
Theisen-Kunde,
Yoko
Miura,
Ralf
Brinkmann, and
Kunihiko
Shiraki,
Selective Retina Therapy for Patients with Central Serous Chorioretinopathy in Japan, Investigative Ophthalmology & Visual Science , vol. 53, pp. 5222, 2012.
Selective Retina Therapy for Patients with Central Serous Chorioretinopathy in Japan, Investigative Ophthalmology & Visual Science , vol. 53, pp. 5222, 2012.
DOI: | 10.1117/1.JBO.17.6.061219 |
Bibtex: | @article{Yamamoto, author = {Yamamoto, Manabu and Kohno, Takeya and Yoshida, Yusaku and Yoneda, Tasuku and Iwami, Hisashi and Fritz, Andreas and Theisen-Kunde, Dirk and Miura, Yoko and Brinkmann, Ralf and Shiraki, Kunihiko}, title = {Selective Retina Therapy for Patients with Central Serous Chorioretinopathy in Japan }, journal = {Investigative Ophthalmology & Visual Science}, volume = {53}, pages = {5222}, year = {2012} } |
Ralf
Brinkmann,
Stefan
Koinzer,
Kerstin
Schlott,
Lars
Ptaszynski,
Marco
Bever,
Alexander
Baade,
Yoko
Miura,
Reginald
Birngruber, and
Johann
Roider,
Realtime temperature determination during retinal photocoagulation on patients, 09 2011. https://doi.org/10.1117/12.875276 .
Realtime temperature determination during retinal photocoagulation on patients, 09 2011. https://doi.org/10.1117/12.875276 .
Weblink: | https://doi.org/10.1117/12.875276 |
Bibtex: | @book{RN5360, author = {Brinkmann, Ralf;Koinzer, Stefan;Schlott, Kerstin;Ptaszynski, Lars;Bever, Marco;Baade, Alex;Miura, Yoko;Birngruber, Reginald and Roider, Johann}, title = {Realtime temperature determination during retinal photocoagulation on patients}, publisher = {SPIE}, volume = {7885}, series = {SPIE BiOS}, url = {https://doi.org/10.1117/12.875276}, year = {2011}, type = {Book} } |
Jens
Horstmann,
Alexander
Baade, and
Ralf
Brinkmann,
Photoacoustic blood vessel detection during surgical laser interventions, SPIE ECBO, 2011. pp. 80920Z-80920Z-6.
Photoacoustic blood vessel detection during surgical laser interventions, SPIE ECBO, 2011. pp. 80920Z-80920Z-6.
Datei: | 12.889635 |
Bibtex: | @inproceedings{Horstmann2011, author = {Horstmann, Jens and Baade, Alexander and Brinkmann, Ralf}, title = {Photoacoustic blood vessel detection during surgical laser interventions}, publisher = {SPIE ECBO}, volume = {8092}, pages = {80920Z-80920Z-6}, note = {10.1117/12.889635}, abstract = {This paper presents a discussion about the potential of photoacoustics with regard to its application in surgical assistance during minimally invasive, laser assisted interventions. Aim of the work is the detection of obscured large blood vessels in order to prevent unintentional dissection. Based on spectroscopic investigations of the target tissue (liver), a wavelength for the photoacoustic excitation laser was chosen with respect to a high absorption contrast between the vessel and the surrounding liver tissue. An experimental setup featuring a simple liver model is created. Preliminary results show, that vessels with a diameter of 2 mm can be detected up to a distance of 1 mm from the treatment fibre. It is shown, that detection of acoustic waves induced inside liver is feasible over distances higher than 10 cm.}, url = {http://dx.doi.org/10.1117/12.889635}, type = {Conference Proceedings}, year = { 2011} } |
Kerstin
Schlott,
Stefan
Koinzer,
Lars
Ptaszynski,
Susanne
Luft,
Marco
Bever,
Johann
Roider, and
Ralf
Brinkmann,
Optoacoustic temperature determination and automatic coagulation control in rabbits, in Ophthalmic Technologies XXI , Ho, Fabrice Manns; Per G. Söderberg; Arthur, Eds. Proc. SPIE, 2011.
Optoacoustic temperature determination and automatic coagulation control in rabbits, in Ophthalmic Technologies XXI , Ho, Fabrice Manns; Per G. Söderberg; Arthur, Eds. Proc. SPIE, 2011.
Datei: | 12.875104 |
Bibtex: | @inproceedings{Schlott2011, author = {Schlott, Kerstin and Koinzer, Stefan and Ptaszynski, Lars and Luft, Susanne and Baade, Alex and Bever, Marco and Roider, Johann and Birngruber, Reginald and Brinkmann, Ralf}, title = {Optoacoustic temperature determination and automatic coagulation control in rabbits}, booktitle = {Ophthalmic Technologies XXI }, editor = {Ho, Fabrice Manns; Per G. Söderberg; Arthur}, publisher = {Proc. SPIE}, volume = {7885}, note = {10.1117/12.875104}, abstract = {Retinal laser photocoagulation is an established treatment method for many retinal diseases like macula edema or diabetic retinopathy. The selection of the laser parameters is so far based on post treatment evaluation of the lesion size and strength. Due to local pigment variations in the fundus and individual transmission the same laser parameters often lead to an overtreatment. Optoacoustic allows a non invasive monitoring of the retinal temperature increase during retinal laser irradiation by measuring the temperature dependent pressure amplitudes, which are induced by short probe laser pulses. A 75 ns/ 523 nm Nd:YLF was used as a probe laser at a repetition rate of 1 kHz, and a cw / 532 nm treatment laser for heating. A contact lens was modified with a ring-shaped ultrasonic transducer to detect the pressure waves at the cornea. Temperatures were collected for irradiations leading to soft or invisible lesions. Based on this data the threshold for denaturation was found. By analyzing the initial temperature increase, the further temperature development during irradiation could be predicted. An algorithm was found to calculate the irradiation time, which is needed for a soft lesion formation, from the temperature curve. By this it was possible to provide a real-time dosimetry by automatically switching off the treatment laser after the calculated irradiation time. Automatically controlled coagulations appear softer and more uniformly.}, keywords = {AutoPhoN}, url = {http://dx.doi.org/10.1117/12.875104}, type = {Conference Proceedings}, year = { 2011} } |
Heike H.
Muller,
Lars
Ptaszynski,
Kerstin
Schlott,
Tim
Bonin,
Marco
Bever,
Stefan
Koinzer, and
Ralf
Brinkmann,
Imaging of temperature distribution and retinal tissue changes during photocoagulation by high speed OCT, James, G. Fujimoto and Joseph, A. Izatt and Valery, V. Tuchin, Eds. SPIE, 2011. pp. 78890E.
Imaging of temperature distribution and retinal tissue changes during photocoagulation by high speed OCT, James, G. Fujimoto and Joseph, A. Izatt and Valery, V. Tuchin, Eds. SPIE, 2011. pp. 78890E.
Datei: | 12.874788 |
Bibtex: | @inproceedings{Müller-2011-2, author = {Muller, Heike H. and Ptaszynski, Lars and Schlott, Kerstin and Bonin, Tim and Bever, Marco and Koinzer, Stefan and Birngruber, Reginald and Brinkmann, Ralf and Huttmann, Gereon}, title = {Imaging of temperature distribution and retinal tissue changes during photocoagulation by high speed OCT}, editor = {James, G. Fujimoto and Joseph, A. Izatt and Valery, V. Tuchin}, publisher = {SPIE}, volume = {7889}, pages = {78890E}, URL = { https://doi.org/10.1117/12.874788}, year = { 2011} } |
Andreas
Fritz,
Andrea
Zegelin,
Lars
Ptaszynski, and
Ralf
Brinkmann,
Dynamics of laser induced micro bubble clusters on tissue phantoms, 2011. pp. 78850S-78850S-6.
Dynamics of laser induced micro bubble clusters on tissue phantoms, 2011. pp. 78850S-78850S-6.
Datei: | 12.875031.short |
Bibtex: | @inproceedings{Fritz2011, author = {Fritz, Andreas and Zegelin, Andrea and Ptaszynski, Lars and Birngruber, Reginald and Brinkmann, Ralf}, title = {Dynamics of laser induced micro bubble clusters on tissue phantoms}, volume = {7885}, pages = {78850S-78850S-6}, note = {10.1117/12.875031}, abstract = {Selective retina treatment (SRT) is a laser based method to treat retinal diseases associated with disorders of the retinal pigment epithelium (RPE) while preserving photoreceptors and choroid. Applying microsecond laser pulses to the 100- 200 strongly absorbing melanin granules inside the RPE cells induces transient micro bubbles which disrupt the cells. Aim of this work is to understand bubble dynamics in clusters with respect to the influence of the adjacent retina. Bubble dynamics were investigated in vitro on porcine RPE. An about 200 μm thick layer of agarose gel was applied to the RPE layer in order to simulate the mechanical properties of retina. Different laser pulse durations from 1 ns (532 nm, Nd:YAG) to 1.7 μs (527 nm, Nd:YLF) were used. The bubbles were investigated interferometrically (fiber interferometer @ 830 nm) and with fast flash photography (25 ns flash duration). Bubble lifetimes were measured. The results show that with retina phantoms the bubble formation threshold was reached at 2.5 times higher irradiation than without retina phantom for 1.7 μs laser pulses. The microbubbles generated with 1 ns laser pulses were almost not influenced by the agarose layer. Irradiation twofold over bubble formation threshold resulted in 3.5 times longer bubble lifetimes for μs and 2 times longer for ns pulse durations, respectively.}, url = {https://www.spiedigitallibrary.org/conference-proceedings-of-spie/7885/1/Dynamics-of-laser-induced-micro-bubble-clusters-on-tissue-phantoms/10.1117/12.875031.short}, type = {Conference Proceedings}, year = { 2011} } |
Akira
Obana,
Ralf
Brinkmann,
Yuko
Gohto, and
Kasumi
Nishimura,
A Case of Retinal Injury By A Violet Light-Emitting Diode, Retinal Cases and Brief Reports , vol. 5, no. 3, pp. 223--226 10.1097/ICB.0b013e3181e180d5, 2011.
A Case of Retinal Injury By A Violet Light-Emitting Diode, Retinal Cases and Brief Reports , vol. 5, no. 3, pp. 223--226 10.1097/ICB.0b013e3181e180d5, 2011.
Akira
Obana,
Ralf
Brinkmann,
Yuko
Gohto, and
Kasumi
Nishimura,
A Case of Retinal Injury By A Violet Light-Emitting Diode, Retinal Cases and Brief Reports , vol. 5, no. 3, pp. 223-226 10.1097/ICB.0b013e3181e180d5, 2011.
A Case of Retinal Injury By A Violet Light-Emitting Diode, Retinal Cases and Brief Reports , vol. 5, no. 3, pp. 223-226 10.1097/ICB.0b013e3181e180d5, 2011.
Yoko
Miura,
Regina
Orzekowsky-Schröder,
Norbert
Koop,
Philipp
Steven,
Márta
Szaszák, and
Ralf
Brinkmann,
Appearance of autofluorescence in RPE cells at the rim of photocoagulation, in FLIM 2010 - Symposium "Fluorescence Lifetime Imaging of the Human Retina" , 2010.
Appearance of autofluorescence in RPE cells at the rim of photocoagulation, in FLIM 2010 - Symposium "Fluorescence Lifetime Imaging of the Human Retina" , 2010.
Kerstin
Schlott,
Jens
Langejürgen,
Marco
Bever,
Stefan
Koinzer, and
Ralf
Brinkmann,
Time resolved detection of tissue denaturation during retinal photocoagulation, 7373, Proc. SPIE, Eds. 2009. pp. 73730E-73730E.
Time resolved detection of tissue denaturation during retinal photocoagulation, 7373, Proc. SPIE, Eds. 2009. pp. 73730E-73730E.
Datei: | 12.168030 |
Bibtex: | @inproceedings{Schlott2009, author = {Schlott, Kerstin and Langejürgen, Jens and Bever, Marco and Koinzer, Stefan and Birngruber, Reginald and Brinkmann, Ralf}, title = {Time resolved detection of tissue denaturation during retinal photocoagulation}, editor = {7373, Proc. SPIE}, pages = {73730E-73730E}, note = {10.1117/12.831877}, abstract = {The retinal photocoagulation is an established treatment method for different retinal diseases. The extent of the thermal coagulations depends strongly on the generated temperature increase. Until now the dosage is based on a pool of experience of the treating physicians as well as the appearance of the whitish lesions on the retina. The temperature course during photocoagulation can be measured in real-time by optoacoustics. A frequency-doubled Q-switched Nd:YLF laser (523nm, 75 ns) is used for optoacoustic excitation and a continuous-wave Nd:YAG laser (532nm) with adjustable irradiation time and power for heating of the fundus tissue. The onset of coagulation is determined by a photodiode that is placed directly behind enucleated porcine eyes, which served as a model. The onset of coagulation is observed clearly when scattering sets in. The required power for coagulation increases exponentially with decreasing irradiation time. The first results on rabbit eyes in vivo indicate that the onset of coagulation defined by just barely visibile lesions at a slit lamp sets in at an ED50 threshold temperature of 63°C for an irradiation time of 400 ms. In conclusion, optoacoustics can be used to determine temperatures during retinal laser treatments in real-time. This allows evaluating the time-temperature-dependence of retinal coagulation in vivo.}, keywords = {AutoPhoN}, url = {http://dx.doi.org/10.1117/12.831877}, type = {Conference Proceedings}, year = { 2009}, url = { https://doi.org/10.1117/12.168030} } |
Andreas
Fritz,
Lars
Ptaszynski,
Hardo
Stoehr, and
Ralf
Brinkmann,
Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE), 2007. pp. 66321C-66321C-11.
Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE), 2007. pp. 66321C-66321C-11.
Datei: | 12.728344 |
Bibtex: | @inproceedings{Fritz2007, author = {Fritz, Andreas and Ptaszynski, Lars and Stoehr, Hardo and Brinkmann, Ralf}, title = {Dynamics and detection of laser induced microbubbles in the retinal pigment epithelium (RPE)}, volume = {6632}, pages = {66321C-66321C-11}, note = {10.1117/12.728344}, abstract = {Selective Retina Treatment (SRT) is a new method to treat eye diseases associated with disorders of the RPE. Selective RPE cell damage is achieved by applying a train of 1.7 μs laser pulses at 527 nm. The treatment of retinal diseases as e.g. diabetic maculopathy (DMP), is currently investigated within clinical studies, however 200 ns pulse durations are under investigation. Transient micro bubbles in the retinal pigment epithelium (RPE) are expected to be the origin of cell damage due to irradiation with laser pulses shorter than 50 μs. The bubbles emerge at the strongly absorbing RPE melanosomes. Cell membrane disruption caused by the transient associated volume increase is expected to be the origin of the angiographically observed RPE leakage. We investigate micro bubble formation and dynamics in porcine RPE using pulse durations of 150 ns. A laser interferometry system at 830 nm with the aim of an online dosimetry control for SRT was developed. Bubble formation was detected interferometrically and by fast flash photography. A correlation to cell damage observed with a vitality stain is found. A bubble detection algorithm is presented.}, url = {http://dx.doi.org/10.1117/12.728344}, type = {Conference Proceedings} } |
Katharina
Herrmann,
Christian
Flöhr,
Jens
Stalljohann,
Gabriela
Apiou-Sbirlea,
Jochen
Kandulla, and
Ralf
Brinkmann,
Influence of choroidal perfusion on retinal temperature increase during retinal laser treatments, 2007. pp. 66321D-66321D-7.
Influence of choroidal perfusion on retinal temperature increase during retinal laser treatments, 2007. pp. 66321D-66321D-7.
Datei: | 12.728222 |
Bibtex: | @inproceedings{Herrmann2007, author = {Herrmann, Katharina and Flöhr, Christian and Stalljohann, Jens and Apiou-Sbirlea, Gabriela and Kandulla, Jochen and Birngruber, Reginald and Brinkmann, Ralf}, title = {Influence of choroidal perfusion on retinal temperature increase during retinal laser treatments}, volume = {6632}, pages = {66321D-66321D-7}, note = {10.1117/12.728222}, abstract = {In most retinal laser treatments the therapeutic effect is initiated by a transient temperature increase at and around the retinal pigment epithelium (RPE). Especially in long exposure time treatments like Transpupillary Thermotherapy (TTT) choroidal perfusion has a strong influence on the realized temperature at the fundus. The fundus blood circulation and therefore the heat dissipation is influenced by the intraocular pressure (IOP), which is investigated in the study presented here. In order to reduce the choroidal perfusion, the IOP is increased by injection of physiological saline solution into the eye of anaesthetized rabbits. The fundus is irradiated with 3.64 W/cm2 by means of a TTT-laser (λ = 810 nm) for t = 20 s causing a retinal temperature increase. Realtime temperature determination at the irradiated spot is achieved by a non invasive optoacoustic technique. Perfusion can be reduced by increasing IOP, which leads to different temperature increases when irradiating the retina. This should be considered for long time laser treatments.}, url = {http://dx.doi.org/10.1117/12.728222}, type = {Conference Proceedings}, year = { 2007} } |
Hardo
Stoehr,
Lars
Ptaszynski,
Andreas
Fritz, and
Ralf
Brinkmann,
Interferometric optical online dosimetry for selective retina treatment (SRT), 2007. pp. 642619-642619-7.
Interferometric optical online dosimetry for selective retina treatment (SRT), 2007. pp. 642619-642619-7.
Datei: | 12.708521 |
Bibtex: | @inproceedings{Stoehr2007-1, author = {Stoehr, Hardo and Ptaszynski, Lars and Fritz, Andreas and Brinkmann, Ralf}, title = {Interferometric optical online dosimetry for selective retina treatment (SRT)}, volume = {6426}, pages = {642619-642619-7}, note = {10.1117/12.708521}, abstract = {In selective retina treatment (SRT) spatial confined tissue damage in the absorbing retinal pigment epithelium (RPE) is obtained by applying microsecond laser pulses. The damage in the RPE is caused by transient microbubbles forming around the laser heated melanin granules inside the cells. For treatment of RPE related diseases, SRT is thought to share the therapeutic benefits of conventional photocoagulation but without affecting the photoreceptors. A drawback for effective clinical SRT is that the laser-induced lesions are ophthalmoscopically invisible. Therefore, a real-time feedback system for dosimetry is demanded in order to avoid undertreatment or unwanted collateral damage to the adjacent tissue. We develop a dosimetry system which uses optical interferometry for the detection of the transient microbubbles. The system is based on an optical fiber interferometer which is operated with a laser diode at 830nm. We present current results obtained with porcine RPE explants in vitro and complete porcine eye globes ex vivo.}, url = {http://dx.doi.org/10.1117/12.708521}, type = {Conference Proceedings}, Year = { 2007} } |
Kerstin
Schlott,
Jens
Stalljohann,
Benjamin
Weber,
Jochen
Kandulla,
Katharina
Herrmann, and
Ralf
Brinkmann,
Optoacoustic online temperature determination during retinal laser photocoagulation, 2007. pp. 66321B-66321B-8.
Optoacoustic online temperature determination during retinal laser photocoagulation, 2007. pp. 66321B-66321B-8.
Datei: | 12.728291 |
Bibtex: | @inproceedings{Schlott2007, author = {Schlott, Kerstin and Stalljohann, Jens and Weber, Benjamin and Kandulla, Jochen and Herrmann, Katharina and Birngruber, Reginald and Brinkmann, Ralf}, title = {Optoacoustic online temperature determination during retinal laser photocoagulation}, volume = {6632}, pages = {66321B-66321B-8}, note = {10.1117/12.728291}, abstract = {Retinal photocoagulation is an established treatment of different retinal diseases. The treatment relies on a short, local heating of the tissue which induces a denaturation. The resulting scar formation may for example prevent the further detachment of the retina. The extent of the coagulation is besides other parameters mostly dependent on the induced temperature increase. However, until today a temperature based dosimetry for photocoagulation does not exist. The dosage is rather based on the experience of the treating physicians to achieve visible whitish lesions on the retina. In this work a technique is presented, which allows an online temperature monitoring during photocoagulation. If an absorbing material is irradiated with short laser pulses, a thermoelastic expansion of the absorber induces an acoustic wave. Its amplitude is dependent on the temperature of the absorber. For analyzing the applicability of the optoacoustic temperature determination for dosimetry, measurements were performed on enucleated porcine eye globes. The pressure transients are detected by an ultrasonic transducer, which is embedded in an ophthalmologic contact lens. As long as no strong lesions occur, the determined temperatures are almost proportional to the power of the treatment laser. Using a spot diameter of 200 μm and different laser powers, the temperature rise at the end of the 400 ms irradiation was found to be approximately 0.16 °C/mW. The onset of the denaturation was observed around 50°C. The far aim of this project is an automatic regulation of the treatment laser onto a desired temperature course.}, url = {http://dx.doi.org/10.1117/12.728291}, type = {Conference Proceedings}, year = { 2007} } |
Ralf Brinkmann,
Selektive Retina-Therapie (SRT), Zeitschrift für Medizinische Physik , vol. 17, no. 1, pp. 6-22, 2006.
Selektive Retina-Therapie (SRT), Zeitschrift für Medizinische Physik , vol. 17, no. 1, pp. 6-22, 2006.