Automatic temperature controlled retinal photocoagulation

作者:Schlott Kerstin*; Koinzer Stefan; Ptaszynski Lars; Bever Marco; Baade Alex; Roider Johann; Birngruber Reginald; Brinkmann Ralf
来源:Journal of Biomedical Optics, 2012, 17(6): 061223.
DOI:10.1117/1.JBO.17.6.061223

摘要

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 degrees C for 20 ms to 49 degrees C for 400 ms. Arrhenius parameters were extracted Delta E = 273 J mol(-1) and A = 3 . 10(44) s(-1). Control algorithms for mild and strong lesions were developed, which led to average lesion diameters of 162 +/- 34 mu m and 189 +/- 34 mu m, 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.

  • 出版日期2012-6