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Journal of Biomedical Optics

Real-time temperature determination during retinal photocoagulation on patients
Author(s): Ralf Brinkmann; Kerstin Schlott; Susanne Luft; Yoko Miura; Reginald Birngruber; Lars Ptaszynski; Marco Bever; Alexander Baade; Stefan Koinzer; Johann Roider
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Paper Abstract

The induced thermal damage in retinal photocoagulation depends on the temperature increase and the time of irradiation. The temperature rise is unknown due to intraocular variations in light transmission, scattering and grade of absorption in the retinal pigment epithelium (RPE) and the choroid. Thus, in clinical practice, often stronger and deeper coagulations are applied than therapeutically needed, which can lead to extended neuroretinal damage and strong pain perception. This work focuses on an optoacoustic (OA) method to determine the temperature rise in real-time during photocoagulation by repetitively exciting thermoelastic pressure transients with nanosecond probe laser pulses, which are simultaneously applied to the treatment radiation. The temperature-dependent pressure amplitudes are non-invasively detected at the cornea with an ultrasonic transducer embedded in the contact lens. During clinical treatment, temperature courses as predicted by heat diffusion theory are observed in most cases. For laser spot diameters of 100 and 300 μm, and irradiation times of 100 and 200 ms, respectively, peak temperatures range between 70°C and 85°C for mild coagulations. The obtained data look very promising for the realization of a feedback-controlled treatment, which automatically generates preselected and reproducible coagulation strengths, unburdens the ophthalmologist from manual laser dosage, and minimizes adverse effects and pain for the patient.

Paper Details

Date Published: 15 May 2012
PDF: 11 pages
J. Biomed. Opt. 17(6) 061219 doi: 10.1117/1.JBO.17.6.061219
Published in: Journal of Biomedical Optics Volume 17, Issue 6
Show Author Affiliations
Ralf Brinkmann, Univ. zu Lübeck (Germany)
Kerstin Schlott, Univ. zu Lübeck (Germany)
Susanne Luft, Univ. zu Lübeck (Germany)
Yoko Miura, Univ. zu Lübeck (Germany)
Reginald Birngruber, Univ. zu Lübeck (Germany)
Lars Ptaszynski, Medizinisches Laserzentrum Lübeck GmbH (Germany)
Marco Bever, Medizinisches Laserzentrum Lübeck GmbH (Germany)
Alexander Baade, Medizinisches Laserzentrum Lübeck GmbH (Germany)
Stefan Koinzer, Univ. Hospital of Schleswig-Holstein (Germany)
Johann Roider, Univ. Hospital of Schleswig-Holstein (Germany)

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