[Photoablation with the Er:YAG laser in ocular tissues]

Photoablation of ocular tissues is not restricted to the excimer laser. Alternative tools are erbium lasers. As there is maximum absorption in ocular tissue at about 3 microns, two types of erbium lasers are capable of photoablation. One is the Er:YAG laser working at a wavelength of 2.94 micron; the other is the Er:YSGG laser emitting light with a wavelength of 2.79 microns. Both lasers produce higher ablation rates than the excimer laser. In comparison to the excimer laser (thermal damage of less than 1 micron), there is more thermal damage in the remaining tissue (3 microns). The lower ablation rate of the Er:YSGG laser due to the greater distance of the wavelength from the absorption maximum can be compensated by a higher output energy and a higher repetition rate (25 Hz). Wound-healing studies in rabbit corneas show no significant differences between the excisions performed with the Er:YAG laser and 193 nm excimer laser.