Optoacoustic measurements during mus-irradiation of the retinal pigment epithelium

摘要

The selective microphotocagulation is a new technique to damage the retinal pigment epithelium (RPE), which is desired for treatment of several retinal diseases. By applying a train of mus laser pulses it is possible to selectively destroy these cells and simultaneously spare the adjoining photoreceptor and neural tissue. We applied mus laser pulses of a Nd:YLF laser (527nm), at a repetition rate of 500Hz to porcine RPE. The light is absorbed in the RPE and by thermoelastic expansion, an optoacoustic (OA) signal will be generated which could be measured by an ultrasonic transducer. With this setup, the baseline temperature increase at the RPE, during irradiation can be determined, since the optoacoustic pressure signal depends on the temperature of the irradiated RPE. We found a linear dependence of the OA amplitude to the RPE sample temperature. At higher irradiance we prooved the formation of microbubbles and bubble collapse in the RPE with OA techniques.