28 July 2017 Real time speckle monitoring to control retinal photocoagulation
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Abstract
Photocoagulation is a treatment modality for several retinal diseases. Intra- and inter-individual variations of the retinal absorption as well as ocular transmission and light scattering makes it impossible to achieve a uniform effective exposure with one set of laser parameters. To guarantee a uniform damage throughout the therapy a real-time control is highly requested. Here, an approach to realize a real-time optical feedback using dynamic speckle analysis in-vivo is presented. A 532 nm continuous wave Nd:YAG laser is used for coagulation. During coagulation, speckle dynamics are monitored by a coherent object illumination using a 633 nm diode laser and analyzed by a CMOS camera with a frame rate up to 1 kHz. An algorithm is presented that can discriminate between different categories of retinal pigment epithelial damage ex-vivo in enucleated porcine eyes and that seems to be robust to noise in-vivo. Tissue changes in rabbits during retinal coagulation could be observed for different lesion strengths. This algorithm can run on a FPGA and is able to calculate a feedback value which is correlated to the thermal and coagulation induced tissue motion and thus the achieved damage.
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Katharina Bliedtner, Katharina Bliedtner, Eric Seifert, Eric Seifert, Ralf Brinkmann, Ralf Brinkmann, } "Real time speckle monitoring to control retinal photocoagulation", Proc. SPIE 10413, Novel Biophotonics Techniques and Applications IV, 1041308 (28 July 2017); doi: 10.1117/12.2287815; https://doi.org/10.1117/12.2287815
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