Microcavitation and cell injury in RPE cells following short-pulsed laser irradiation

Our research investigates the mechanism of retinal injury from short laser pulses. We used an ex-vivo porcine model and time resolved strobe imaging to examine mechanical effects associated with sub-nanosecond absorption by the retinal pigment epithelium (RPE). We present a unique method of imaging high speed events in the RPE with a resolution of approximately 1 mu m. Microcavitation bubbles were first imaged around single melanosomes, after irradiation with a 40 ps, 532 nm pulse. The threshold for bubble formation was 50 mJ/cm(2) A few times threshold, stress waves could be observed around the melanosomes. At 0.68 J/cm(2) we measured shock waves with an average velocity of 2700 m/s, 1 ns after irradiation. After exposures above 50 mJ/cm(2) RPE cells were found to be non-viable. We compare these results with MVL data collected using live animal models.