PHOTOVAPORIZATION RATE AND PROFILE OF AN ERBIUM-CHROMIUM-YAG LASER INTHE FUNDAMENTAL MODE

Purpose: To evaluate the ablation characteristics of an experimental e rbium:YAG (Er:YAG) laser and assess whether it delivers sufficient out put for performing photorefractive keratectomy. Setting: Department of Ophthalmology, Virchow-Clinics, Humboldt University, Berlin, Germany. Methods: An experimental Er:YAG laser, the erbium-chromium:YAG, runni ng in fundamental mode was used to evaluate the energy profile. Measur ements obtained using a joulemeter were compared to the ablation profi les of cadaver pig eyes. The pig eyes were treated with different flue nces (mean 0.8 to 2.9 J/cm(2)) and, after histological preparation, we re examined using light and scanning electron microscopy. Results: Mea surements with the joulemeter and in the cadaver pig eyes showed a Gau ssian-curved profile of energy (ablation). In the current setting, the diameter of ablation was 3.5 mm. Histological examination showed a ho mogeneous profile of ablation with minor thermal damage. Conclusion: T he Er:YAG laser running in the fundamental mode allows homogeneous abl ation of corneal tissue. The Er:YAG laser is easier to handle technica lly than the excimer laser and has none of the potential risks of ultr aviolet light.