Optical and thermal mechanisms related to the design of laser sclerostomy

Collateral, thermally induced structural damage during laser sclerostomy ab interno or ab externo was investigated theoretically and compared with experimental results. We show that collateral heat damage in contact strategies using fiber delivery is mainly due to heat conductivity following explosive ablation. Electron micrographs of perforated porcine eyes show that the damage is only weakly dependent on the laser wavelength. The experiments also demonstrate that simultaneous application of laser irradiation and pressure with the fiber tip yield efficient perforation of scleral tissue even when the weakly absorbed radiation of Nd:YAG or diode lasers is employed.