September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Visibility limits of realtime temperature controlled photocoagulation in OCT, fluorescence angiography and funduscopy in rabbits
Author Affiliations & Notes
  • Meike Lawin
    Medizinisches Laserzentrum Luebeck GmbH, Luebeck, Germany
  • Alexander Baade
    Medizinisches Laserzentrum Luebeck GmbH, Luebeck, Germany
  • Kerstin Schlott
    Medizinisches Laserzentrum Luebeck GmbH, Luebeck, Germany
  • Stefan Koinzer
    Department of Ophthalmology, University of Kiel, Kiel, Germany
  • Claus vonderBurchard
    Department of Ophthalmology, University of Kiel, Kiel, Germany
  • Johann Roider
    Department of Ophthalmology, University of Kiel, Kiel, Germany
  • Ralf Brinkmann
    Medizinisches Laserzentrum Luebeck GmbH, Luebeck, Germany
    University of Luebeck, Institute of Biomedical Optics, Luebeck, Germany
  • Footnotes
    Commercial Relationships   Meike Lawin, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F); Alexander Baade, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F); Kerstin Schlott, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F); Stefan Koinzer, None; Claus vonderBurchard, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F); Johann Roider, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F); Ralf Brinkmann, Carl Zeiss Meditec (F), RS Medizintechnik (F), Thorlabs (F), Zeiss AG (F)
  • Footnotes
    Support  13GW0043 B
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5850. doi:
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      Meike Lawin, Alexander Baade, Kerstin Schlott, Stefan Koinzer, Claus vonderBurchard, Johann Roider, Ralf Brinkmann; Visibility limits of realtime temperature controlled photocoagulation in OCT, fluorescence angiography and funduscopy in rabbits. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5850.

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

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Abstract

Purpose : Photocoagulation is a common treatment for retinal diseases. Due to variations in the pigmentation of RPE and choroid, the strength of the lesions vary when using the same laser parameters. The coagulation of a lesion strongly depends on the induced temperature rise during irradiation. We developed a non-invasive technique to measure the temperature rise during laser irradiation by means of optoacoustics. In this work we control the induced temperature at the end of the irradiation (aim temperature) of each spot. We chose certain different aim temperatures and examine the lesions appearances and visibility limits with different imaging techniques.

Methods : Two lasers are used: a VISULAS532s (Carl Zeiss Meditec AG,532nm wavelength) for heating and a pulsed laser (CrystaLaser QG-523-1000, 523nm wavelength,75ns pulse duration,1kHz repetition rate) for real-time temperature determination. Both beams are coupled into one multimode fiber (50µm core diameter, NA=0.1) of a slit lamp (Zeiss LSL 532s) to focus a spot (200µm beam diameter) on the retina. The treatment laser heats the tissue continuously within 40ms, while the laser pulses repetitively introduce additional temperature changes within the treated tissue. The resulting short thermoelastic expansions cause the emission of ultrasonic pressure waves which contain the temperature information of the treated area. The pressure waves are detected at the cornea by an embedded detector within a contact glass (Ocular Mainster Focal/Grid). This data is used to adjust laser power after treatment half-time of irradiation to obtain the aim temperature. Using a Cirrus HD-OCT, the strength of the lesions are investigated using a OCT, fluorescence-angiography and funduscopy.

Results : The funduscopically and angiographically investigated lesions at 50°C stay invisible. The probability of producing visible lesions is 50% at a temperature of 57°C. Further OCT investigations will show which distinct retinal layers are affected by different aim temperatures.

Conclusions : We control the temperature of laser irradiated spots in real-time in vivo by optoacoustics. These investigations show the visibility limits of the lesions at chosen aim temperatures for OCT, fluorescence-angiography and funduscopy. This can be useful for a better understanding of the photocoagulation processes and therefore may prevent over- or undertreatment.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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