Georg
Schuele,
Gereon
Huettmann, and
Ralf
Brinkmann,
Noninvasive temperature measurements during laser irradiation of the retina with optoacoustic techniques, Fabrice, Manns and Per, G. Soederberg and Arthur, Ho, Eds. Proc. SPIE, 2002. pp. 64-71.
Noninvasive temperature measurements during laser irradiation of the retina with optoacoustic techniques, Fabrice, Manns and Per, G. Soederberg and Arthur, Ho, Eds. Proc. SPIE, 2002. pp. 64-71.
Datei: | 12.470601 |
Bibtex: | @inproceedings{Schuele-2002, author = {Schuele, Georg and Huettmann, Gereon and Brinkmann, Ralf}, title = {Noninvasive temperature measurements during laser irradiation of the retina with optoacoustic techniques}, editor = {Fabrice, Manns and Per, G. Soederberg and Arthur, Ho}, publisher = {Proc. SPIE}, volume = {4611}, pages = {64-71}, year = { 2002}, url = { https://doi.org/10.1117/12.470601} } |
Jan
Rommerscheid,
Dirk
Theisen,
G.
Schmuecker,
Ralf
Brinkmann, and
R.
Broll,
Myocardial expression of the vascular endothelial growth factor (VEGF) after endocardial laser revascularization (ELR), 2001. pp. 39-44.
Myocardial expression of the vascular endothelial growth factor (VEGF) after endocardial laser revascularization (ELR), 2001. pp. 39-44.
Datei: | 12.446529 |
Bibtex: | @inproceedings{Rommerscheid2001, author = {Rommerscheid, Jan and Theisen, Dirk and Schmuecker, G. and Brinkmann, Ralf and Broll, R.}, title = {Myocardial expression of the vascular endothelial growth factor (VEGF) after endocardial laser revascularization (ELR)}, volume = {4433}, pages = {39-44}, note = {10.1117/12.446529}, abstract = {Background. Endocardial laser revascularization (ELR) is a new technique to treat patients with severe coronary artery disease (CAD) in a percutaneous approach. The results show a significant improvement of symptoms, but the mechanism of action is still unknown. One main theory is the angiogenesis for which Vascular Endothelial Growth Factor (VEGF) is the keypromotor. We investigated immunohistochemically the VEGF-expression after ELR in porcine hearts over a timeperiod of four weeks. Methods. ELR was performed with a single-pulse Thulium:YAG laser. 15 pigs were treated with ELR and the hearts were harvested at five timeperiods: directly (group I), 3 days (group II), 1 week (group III), 2 weeks (group IV) and 4 weeks (group V) after ELR. Each group consisted of three pigs. Immunohistochemically the VEGF-expression was assessed by staining with a polyclonal antibody against VEGF and cellcounting using an expression index (VEGF-EI) Results. A maximum of VEGF-expression was found three days (group II) after ELR with a VEGF-EI of 97%. At 1 week (group III) the VEGF-EI was similar high with 93%. Along the timecourse the index decreased to 22% at 4 weeks (groupV). Conclusions. Our findings show that ELR leads to an local upregulation of VEGF around the channels. The resulting angiogenesis could be the mechanism for the relief of angina.}, url = {http://dx.doi.org/10.1117/12.446529}, type = {Conference Proceedings}, year = { 2001} } |
Georg
Schuele,
Elke
Joachimmeyer,
Carsten
Framme,
Johann
Roider, and
Ralf
Brinkmann,
Optoacoustic control system for selective treatment of the retinal pigment epithelium, 2001. pp. 71-76.
Optoacoustic control system for selective treatment of the retinal pigment epithelium, 2001. pp. 71-76.
Datei: | 12.429323 |
Bibtex: | @inproceedings{Schuele2001, author = {Schuele, Georg and Joachimmeyer, Elke and Framme, Carsten and Roider, Johann and Birngruber, Reginald and Brinkmann, Ralf}, title = {Optoacoustic control system for selective treatment of the retinal pigment epithelium}, volume = {4256}, pages = {71-76}, note = {10.1117/12.429323}, abstract = {The selective damage of the retinal pigment epithelium (RPE) is a new treatment method for several retinal diseases. By applying a train of microsecond(s) laser pulses it is possible to selectively damage these cells and simultaneously spare the adjacent photoreceptor and neural tissue. Due to the ophthalmologic invisibility of the RPE cell damage we investigate an optoacoustic (OA) control system to monitor the RPE cell damage. Setup: The irradiation was performed with a frequency doubled Nd:YLF laser by applying a train of +s laser pulses. In vitro, the OA transients were received by an ultrasonic broadband transducer. During treatment an OA contact lens with embedded transducer was used. In vitro: Freshly enucleated porcine RPE samples with CalceinAM as life/death staining were used. Below RPE cell damage threshold a classic thermoelastic transient was found. Above cell damage threshold the OA transient differs form pulse to pulse. This can be explained by microbubble formation around the strong absorbing melanosomes inside the RPE cells. In vivo: We found the same pulse to pulse deviations of the OA transient above the fluoresceine angiographic detectable RPE damage threshold during treatment. This system give us a new approach to non-invasively monitor the selective RPE treatment.}, url = {http://dx.doi.org/10.1117/12.429323}, type = {Conference Proceedings}, year = { 2001} } |
Georg
Schuele,
Elke
Joachimmeyer,
Carsten
Framme,
Johann
Roider, and
Ralf
Brinkmann,
Optoacoustic detection of selective RPE cell damage during μs-laser irradiation, 2001. pp. 92-96.
Optoacoustic detection of selective RPE cell damage during μs-laser irradiation, 2001. pp. 92-96.
Datei: | 12.446507 |
Bibtex: | @inproceedings{Schuele2001-1, author = {Schuele, Georg and Joachimmeyer, Elke and Framme, Carsten and Roider, Johann and Birngruber, Reginald and Brinkmann, Ralf}, title = {Optoacoustic detection of selective RPE cell damage during μs-laser irradiation}, volume = {4433}, pages = {92-96}, note = {10.1117/12.446507}, abstract = {Objective: The selective damage of the retinal pigment epithelium (RPE) with repetitive microsecond(s) laser pulses is a new technique for the treatment of several retinal diseases. RPE can selectively be damaged by simultaneously sparing off the adjacent photoreceptor tissue. Objective of this study is to investigate whether optoacoustic (OA) transients occurring during irradiation might be used to control the invisible treatment effect. Setup: A train of frequency doubled Nd:YLF laser pulses (527 nm, 1.7microsecond(s) pulse length, 500Hz rep. rate) were applied via a laser slit lamp on porcine RPE samples. The acoustic transients were recorded with a broadband transducer. Results: At low radiant exposures (<100 mJ/cm2) we found a bipolar pressure transient due to thermo-elastic expansion of the RPE. The pressure waves from the individual pulses of one pulse train show nearly identical transients. The transients differ slightly from different sites on the sample. At higher radiant exposures (>150 mJ/cm2), the OA transients differ from pulse to pulse within a pulse train, which can be attributed to microbubble formation around the strong absorbing melanosomes inside the RPE cells. FFT spectra of the OA transients show slight differences in the frequency spectrum with the different radiant exposures.}, url = {http://dx.doi.org/10.1117/12.446507}, type = {Conference Proceedings}, year = { 2001} } |
Norbert
Koop,
Ralf
Brinkmann,
Eva
Lankenau,
Stefan
Flache, and
Ralf
Engelhardt,
Optische Kohärenztomographie der Kornea und des vorderen Augenabschnitts, Der Ophthalmologe , vol. 94, no. 7, pp. 481-486, 1997.
Optische Kohärenztomographie der Kornea und des vorderen Augenabschnitts, Der Ophthalmologe , vol. 94, no. 7, pp. 481-486, 1997.
Datei: | s003470050143 |
Bibtex: | @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} } |
Ralf
Brinkmann,
Juergen
Kampmeier,
Ulf
Grotehusmann,
Alfred
Vogel,
Norbert
Koop, and
Mary
Asiyo-Vogel,
Corneal collagen denaturation in laser thermokeratoplasty, 1996. pp. 56-63.
Corneal collagen denaturation in laser thermokeratoplasty, 1996. pp. 56-63.
Datei: | 12.239611 |
Bibtex: | @inproceedings{Brinkmann1996-7, 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}, Year ={ 1996} } |