gms | German Medical Science

25th Annual Meeting of the German Retina Society

German Retina Society

01.06. - 02.06.2012, Münster

OCT-endpoint, automatic temperature control facilitates ophthalmoscopically sub-threshold retinal photocoagulation

Meeting Abstract

  • Stefan Koinzer - Universitäts-Augenklinik Kiel
  • K. Schlott - Institut für biomedizinische Optik, Universität zu Lübeck
  • L. Portz - Universitäts-Augenklinik Kiel
  • C. Hesse - Universitäts-Augenklinik Kiel
  • S. Kleemann - Universitäts-Augenklinik Kiel
  • N. Kielhorn - Universitäts-Augenklinik Kiel
  • A. Baade - Medizinisches Laserzentrum Lübeck GmbH
  • M. Saeger - Universitäts-Augenklinik Kiel
  • R. Denner - Carl Zeiss Meditec, Jena
  • L. Ptaszynski - Medizinisches Laserzentrum Lübeck GmbH
  • M. Bever - Medizinisches Laserzentrum Lübeck GmbH
  • R. Birngruber - Institut für biomedizinische Optik, Universität zu Lübeck
  • R. Brinkmann - Medizinisches Laserzentrum Lübeck GmbH
  • J. Roider - Universitäts-Augenklinik Kiel

German Retina Society. 25th Annual Conference of the German Retina Society. Münster, 01.-02.06.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. Doc12rg65

doi: 10.3205/12rg65, urn:nbn:de:0183-12rg655

This is the translated version of the article.
The original version can be found at:

Published: May 30, 2012

© 2012 Koinzer et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Introduction: To minimize side-effects, soft retinal photocoagulation has been attempted by shorter irradiation times or micropulse laser. None of these techniques has a practicable effect control for ophthalmoscopically invisible lesions. We introduce a newly developped device that monitors retinal temperature and allows to automatically control effective yet ophthalmoscopically invisible laser lesions.

Methods: Based on optoacoustic measurements, we monitored the retinal temperature profile during treatment irradiation non-invasively and in real time. Temperatures of 500 photocoagulation lesions in patients were correlated to high-resolution OCT findings. An automatic, temperature-feedback exposure time control was applied to 1000 lesions in rabbits and lesions examined by high-resolution OCT and by histology in another 300 lesions.

Results: 7 characteristic classes of lesions were discernible in OCT images. 3 of these were predominantly invisible and softer than ETDRS lesions. They correlated to temperatures below 70°C. The automatic exposure time control created very soft lesions with an ophthalmoscopic diameter equal to the treatment beam, where the inner retinal layers were histologically intact. 2 classes of even softer lesions were visible in OCT images, but with a decreasing proportion in ophthalmoscopy. Another 2 stronger classes had increasing fundus lesion diameters and OCT damage intensities. Exemplary data of automatically controlled lesion in patients show, that the device is suitable for clinical use.

Conclusions: Using optoacoustic real-time temperature profiling, it is possible to generate ophthalmoscopically invisible photocoagulation lesions, that are visible in OCT images. The new technique allows to transfer recent findings to clinical practise, that imply clinical effectiveness of sub-threshold lesions.