@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}
}

@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}
}

@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}
}

@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}
}