Dynamics of ArF excimer laser-induced cavitation bubbles in gel surrounded by a liquid medium.

BACKGROUND AND OBJECTIVE Cavitation bubbles have been shown to be the driving force of tissue cutting in 193 nm ArF excimer laser-based vitreoretinal microsurgery. In the present work we investigate the dynamics of cavitation bubbles inside a gelatin gel in a saline environment using fast flash microphotography. STUDY DESIGN/MATERIALS AND METHODS The screening influence of the saline medium was found to restrict the maximal distance between the tip and the tissue at which cavitation bubbles are created to < 100 microns at an energy fluence up to 0.3 J/cm2/pulse (the maximal energy fluence applied in vitreoretinal surgery). RESULTS AND CONCLUSION Single laser pulses did not cause disruption of gelatin at an energy fluence of up to 0.4 J/cm2/pulse. During the application of repetitive pulses small insoluble gas-containing bubbles were produced and often trapped between the tip and the tissue. They completely changed the shape of the subsequent cavitation bubbles and caused deep crater formation in the gel.