Realtime temperature control towards gentle photocoagulation of the retina

Ralf Brinkmann*, K. Schlott, L. Baessler, K. Herrmann, W. Xia, M. Bever, R. Birngruber

*Corresponding author for this work


Retinal laser photocoagulation is the most successful laser therapy in medicine and well established for a variety of retinal diseases. However, the laser induced retinal temperature increase for photocoagulation is so far unknown. In order to probe this temperature rise, pulsed laser radiation is repetitively applied to excite pressure waves at the chorioretinal complex simultaneously during the heating time. The pressure waves are detected with an ultrasonic transducer embedded in the contact lens which is placed on the cornea anyway for treatment. From the pressure amplitudes the transient temperature increase at the retina are deduced. A Nd:YLF laser (527 nm) with a pulse duration of 200 ns was used to excite thermoelastic expansion, freshly enucleated porcine eyes served as model. Irradiation with a constant power of 175 mW onto 400 μm spots of medium pigmented eyes lead to a temperature rise of 35 K after 500 ms with an approximately logarithmic temperature rise over time as expected from the heat diffusion theory. Applying pulses of 200 ms with different powers, we found a temperature rise of 0.18 K/mW at the end of the irradiation period. These first retinal temperature measurements demonstrate the possibility to realize a non-invasive real time temperature monitoring during laser irradiation. The data achieved show very promising towards realization of an automatic dosimetry control almost independent of the individual eye's transmission and pigmentation.

Original languageEnglish
Title of host publication4th European Conference of the International Federation for Medical and Biological Engineering
EditorsJos Vander Sloten, Pascal Verdonck, Marc Nyssen, Jens Haueisen
Number of pages4
Place of PublicationBerlin Heidelberg
PublisherSpringer-Verlag Berlin Heidelberg
Publication date2008
ISBN (Print)978-3-540-89207-6
ISBN (Electronic)978-3-540-89208-3
Publication statusPublished - 2008
Event4th European Conference of the International Federation for Medical and Biological Engineering - Antwerp, Belgium
Duration: 23.11.200827.11.2008
Conference number: 81647

Research Areas and Centers

  • Academic Focus: Biomedical Engineering


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