Photovaporization rate and profile of an erbium-chromium:YAG laser in the fundamental mode.

Purpose: To evaluate the ablation characteristics of an experimental erbium:YAG (Er:YAG) laser and assess whether it delivers sufficient output for performing photorefractive keratectomy.

Setting: Department of Ophthalmology, Virchow-Clinics, Humboldt University, Berlin, Germany.

Methods: An experimental Er:YAG laser, the erbium-chromium:YAG, running in fundamental mode was used to evaluate the energy profile. Measurements obtained using a joulemeter were compared to the ablation profiles of cadaver pig eyes. The pig eyes were treated with different fluences (mean 0.8 to 2.9 J/cm2) and, after histological preparation, were examined using light and scanning electron microscopy.

Results: Measurements with the joulemeter and in the cadaver pig eyes showed a Gaussian-curved profile of energy (ablation). In the current setting, the diameter of ablation was 3.5 mm. Histological examination showed a homogeneous profile of ablation with minor thermal damage.

Conclusion: The Er:YAG laser running in the fundamental mode allows homogeneous ablation of corneal tissue. The Er:YAG laser is easier to handle technically than the excimer laser and has none of the potential risks of ultraviolet light.