Ocular Damage Induced by Ultrashort Laser Pulses

A study has been conducted of interaction effects and damage mechanisms of ultrashort laser pulses in the eye. The preliminary results reported here utilized rabbit subjects and ocular tissues isolated from the rabbit eye. Pulsewidths ranged from 4 ns down to 90 fs. In every case, a visible wavelength was used--either doubled Nd:YAG at 532 nm or the 580-nm output of a pumped dye laser. In the living subjects we determined, for each pulsewidth, the threshold for minimally visible lesions (MVLs). In addition, we noted the energy doses required to induce hemorrhagic lesions relative to the corresponding MVLs and use these data to aid in the interpretation of the damage and energy dispersal mechanisms following absorption of ultrashort laser pulses. The ultrashort-pulse beam was directed through flat preparations of rabbit corneas and vitreous fluid and through intact rabbit lenses. Measurements were made to detect pulsewidth broadening or modulation, spectral broadening or white-light continuum generation, second-harmonic generation, and self-focusing or defocusing. These measurements, chosen as indicators of interactions as the ultrashort pulse passes through the ocular medium, were all negative. Cornea, Eye, Femtoseconds, Hemorrhage, Lens, Ocular damage, Picoseconds, Retina, Ultrashort-pulse laser, Vitreous