Research Papers: Therapeutic

Lesion strength control by automatic temperature guided retinal photocoagulation

[+] Author Affiliations
Kerstin Schlott, Reginald Birngruber, Ralf Brinkmann

University of Lübeck, Institute of Biomedical Optics, Peter-Monnik-Weg 4, 23562 Lübeck, Germany

Stefan Koinzer, Johann Roider

University of Kiel, Department of Ophthalmology, Arnold-Heller-Straße 3, House 25, 24105 Kiel, Germany

Alexander Baade

Medical Laser Center Lübeck, Lübeck, Peter-Monnik-Weg 4, 23562 Lübeck, Germany

J. Biomed. Opt. 21(9), 098001 (Sep 27, 2016). doi:10.1117/1.JBO.21.9.098001
History: Received April 20, 2016; Accepted August 26, 2016
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Abstract.  Laser photocoagulation is an established treatment for a variety of retinal diseases. However, when using the same irradiation parameter, the size and strength of the lesions are unpredictable due to unknown inter- and intraindividual optical properties of the fundus layers. The aim of this work is to investigate a feedback system to generate desired lesions of preselectable strengths by automatically controlling the irradiation time. Optoacoustics were used for retinal temperature monitoring. A 532-nm continuous wave Nd:YAG laser was used for photocoagulation. A 75-ns/523-nm Q-switched Nd:YLF laser simultaneously excited temperature-dependent pressure transients, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. The temperature data were analyzed during the irradiation by a LabVIEW routine. The treatment laser was switched off automatically when the required lesion strength was achieved. Five different feedback control algorithms for different lesion sizes were developed and tested on rabbits in vivo. With a laser spot diameter of 133  μm, five different lesion types with ophthalmoscopically visible diameters ranging mostly between 100 and 200  μm, and different appearances were achieved by automatic exposure time control. The automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.

Figures in this Article
© 2016 Society of Photo-Optical Instrumentation Engineers

Topics

Lasers ; Strength ; Tissues ; Retina

Citation

Kerstin Schlott ; Stefan Koinzer ; Alexander Baade ; Reginald Birngruber ; Johann Roider, et al.
"Lesion strength control by automatic temperature guided retinal photocoagulation", J. Biomed. Opt. 21(9), 098001 (Sep 27, 2016). ; http://dx.doi.org/10.1117/1.JBO.21.9.098001


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