Newly designed automated feedback-controlled retinal laser coagulation system

Abstract

Purpose. To investigate the possibility of conducting controlled laser coagulation of the retina using the feedback principle based on automated video monitoring. Material and methods. The developed automated system of laser coagulation of the retina with feedback has been tested on the fundus model in vitroand in vivoon the eyes of rabbits. The uniformity of coagulates in brightness and the required time of coagulate formation for the selected laser exposure modes were investigated. Results. On the fundus model and on the eyes of rabbits at a laser radiation power of 100, 140, 200 and 300 mW at each of the tested brightness levels in the range of 5–70% of the background value, uniform burns in brightness (coefficient of variation less than 10%) were obtained. The duration of the coagulate formation in automatic mode directly depended on the laser power: at a power of 200 and 300 mW, it did not exceed 0.3 s, at a power of 100 mW and a given brightness, it exceeded 1 s by more than 50%. With a power of 200 and 300 mW, the actual brightness was greater than planned in the range of 5–15% of the background level. With a power of 140 mW, there was no difference between the actual and planned brightness, and the duration of coagulate formation did not exceed 0.6 s with a burn brightness of 70% of the background. Conclusion. The new automated system of laser coagulation of the retina with feedback has great potential for development and implementation in clinical practice, allowing to carry out laser exposure on the fundus in vitroand in vivoto obtain reproducible threshold and near-threshold effects. Key words: retina, laser coagulation, laser system, feedback system