June 2022
Volume 63, Issue 7
Open Access
ARVO Annual Meeting Abstract  |   June 2022
Improved Accuracy in Retinal Laser Therapy by Real-Time Temperature Control
Author Affiliations & Notes
  • Claus von der Burchard
    Department of Ophthalmology, Christian-Albrechts-Universitat zu Kiel, Kiel, Schleswig-Holstein, Germany
  • Christopher Kren
    Medical Laser Center Lübeck, Lübeck, Germany
  • Veit Danicke
    Medical Laser Center Lübeck, Lübeck, Germany
  • Jan-Erik Fleger
    Department of Ophthalmology, Christian-Albrechts-Universitat zu Kiel, Kiel, Schleswig-Holstein, Germany
  • Mario Mordmüller
    Medical Laser Center Lübeck, Lübeck, Germany
  • Sebastian Wittmeier
    CureFab Technologies, München, Germany
  • Dirk Theisen-Kunde
    Medical Laser Center Lübeck, Lübeck, Germany
  • Johann Roider
    Department of Ophthalmology, Christian-Albrechts-Universitat zu Kiel, Kiel, Schleswig-Holstein, Germany
  • Ralf Brinkmann
    Medical Laser Center Lübeck, Lübeck, Germany
    Institute for Biomedical Optics, University of Lübeck, Lübeck, Germany
  • Footnotes
    Commercial Relationships   Claus von der Burchard None; Christopher Kren None; Veit Danicke None; Jan-Erik Fleger None; Mario Mordmüller None; Sebastian Wittmeier CureFab Technologies, Code E (Employment), CureFab Technologies, Code I (Personal Financial Interest), CureFab Technologies, Code O (Owner); Dirk Theisen-Kunde None; Johann Roider None; Ralf Brinkmann Medizinisches Laserzentrum Lübeck GmbH, Code P (Patent)
  • Footnotes
    Support  German Federal Ministry of Education and Research (BMBF) Grant 13N13766
Investigative Ophthalmology & Visual Science June 2022, Vol.63, 3800 – F0221. doi:
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      Claus von der Burchard, Christopher Kren, Veit Danicke, Jan-Erik Fleger, Mario Mordmüller, Sebastian Wittmeier, Dirk Theisen-Kunde, Johann Roider, Ralf Brinkmann; Improved Accuracy in Retinal Laser Therapy by Real-Time Temperature Control. Invest. Ophthalmol. Vis. Sci. 2022;63(7):3800 – F0221.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : In retinal laser treatment, the tissue effect only partially correlates to laser energy due to differences in light absorption, light scattering and retinal pigmentation. Especially in subvisible laser treatment, the therapeutic accuracy is low. Thus, treatment reliability and reproducibility are limited.
We have previously reported on real-time temperature-guided retinal laser therapy to improve reproducibility. In this study, we report on the correlation of retinal temperature and laser-tissue effect.

Methods : A conventional 532nm continuous wave laser (Zeiss VisuLas 532) is used with a custom-build modulation module (Medical Laser Center Lübeck), which can measure the temperature rise in real-time with a rate of 3 kHz. Based on this, it controls the laser power in real-time such that a desired target temperature is quickly obtained and held for the rest of the irradiation.
Irradiations with target temperatures from 45 to 69 °C were performed in rabbits with a diameter of 200 µm and an exposure time of 100ms. With a laboratory PC-controlled module, we performed irradiations in 5 eyes of 3 rabbits. For an upcoming clinical study, it was converted to a microcontroller-based system, with which so far 1 eye of 1 rabbit was treated. Funduscopy, optical coherence tomography (OCT) and fluorescence angiography (FAG) were used for evaluation.

Results : With the PC system, the following ED-50 values were determined: Funduscopic visibility 60.2 °C, FAG visibility 60.2 °C, OCT visibility 59.4 °C. In OCT, the greatest linear diameter (GLD) of the lesions correlated better to temperature (R2 = 0.62) than to laser power (R2 = 0.47). The aim temperature was reached with an average error of 3.5%.
With the microcontroller system, comparable results could be reproduced. The average error in aim temperature was 2.3% (97% of lesions within a maximum error of 5%). ED-50 values were comparable in FAG (61.9 °C) and slightly higher in funduscopy (68.2 °C; pilot data with small sample size).

Conclusions : It could be shown that temperature-guided laser irradiations can improve accuracy in retinal laser therapy. Lesion strength is better correlated to temperature than to bare laser power. We are planning to begin a clinical study for temperature-guided non-damaging laser treatment in patients with central serous chorioretinopathy in early 2022.

This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.

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