7 May 2012 Automatic temperature controlled retinal photocoagulation
Author Affiliations +
J. of Biomedical Optics, 17(6), 061223 (2012). doi:10.1117/1.JBO.17.6.061223
Laser coagulation is a treatment method for many retinal diseases. Due to variations in fundus pigmentation and light scattering inside the eye globe, different lesion strengths are often achieved. The aim of this work is to realize an automatic feedback algorithm to generate desired lesion strengths by controlling the retinal temperature increase with the irradiation time. Optoacoustics afford non-invasive retinal temperature monitoring during laser treatment. A 75  ns/523  nm Q-switched Nd:YLF laser was used to excite the temperature-dependent pressure amplitudes, which were detected at the cornea by an ultrasonic transducer embedded in a contact lens. A 532 nm continuous wave Nd:YAG laser served for photocoagulation. The ED50 temperatures, for which the probability of ophthalmoscopically visible lesions after one hour in vivo in rabbits was 50%, varied from 63°C for 20 ms to 49°C for 400 ms. Arrhenius parameters were extracted as ΔE = 273  J mol−1 and A = 3·1044  s−1. Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162±34  μm and 189±34  μm, respectively. It could be demonstrated that the sizes of the automatically controlled lesions were widely independent of the treatment laser power and the retinal pigmentation.
Kerstin Schlott, Reginald Birngruber, Ralf Brinkmann, Stefan Koinzer, Johann Roider, Lars Ptaszynski, Marco Bever, Alexander Baade, "Automatic temperature controlled retinal photocoagulation," Journal of Biomedical Optics 17(6), 061223 (7 May 2012). https://doi.org/10.1117/1.JBO.17.6.061223

Temperature metrology

Laser coagulation

Automatic control


Laser damage threshold


In vivo imaging

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