Realtime temperature determination during retinal photocoagulation on patients

Ralf Brinkmann, Stefan Koinzer, Kerstin Schlott, Lars Ptaszynski, Marco Bever, Alex Baade, Susanne Luft, Yoko Miura, Reginald Birngruber, Johann Roider


Retinal photocoagulation is a long time established treatment for a variety of retinal diseases, most commonly applied for diabetic macular edema and diabetic retinopathy. The damage extent of the induced thermal coagulations depend on the temperature increase and the time of irradiation. So far, the induced temperature rise is unknown due to intraocular variations in light transmission and scattering and RPE/choroidal pigmentation, which can vary inter- and intraindividually by more than a factor of four. Thus in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which lead to extended retinal damage and strong pain perception. The final goal of this project focuses on a dosimetry control, which automatically generates a desired temperature profile and thus coagulation strength for every individual coagulation spot, ideally unburden the ophthalmologist from any laser settings. In this paper we present the first realtime temperature measurements achieved on patients during retinal photocoagulation by means of an optoacoustic method, making use of the temperature dependence of the thermal expansion coefficient of retinal tissue. Therefore, nanosecond probe laser pulses are repetitively and simultaneously applied with the treatment radiation in order to excite acoustic waves, which are detected at the cornea with an ultrasonic transducer embedded in the contact lens and then are processed by PC.

Original languageEnglish
Title of host publicationProc SPIE
Publication date01.04.2011
Publication statusPublished - 01.04.2011


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