STUDY OF PHOTOABLATION OF RABBIT CORNEAS BY ER-YAG LASER

Background and Objective: This work studied the ablation mechanisms of rabbit corneas by the Erbium:YAG laser. The occurrence of thermal and mechanical damages in the tissue as a function of the laser fluence w as also investigated. Study Design/Materials and Methods: The experime nts were performed both on enucleated eyes and in vivo. An ultrafast i maging technique was used to investigate the dynamic evolution of the ablation. The treated samples underwent histological and ultrastructur al study. Results: A single high fluence laser shot led to the complet e removal of the epithelium by a photomechanical effect. In eyes whose epithelium was manually removed, high fluence pulses resulted in evid ent tears in the stroma, whereas low fluence pulses led to few microns deep incisions, characterized by limited mechanical and thermal damag es. Conclusion: The photomechanical action plays a significant role in the ablation of the cornea by Erbium laser. Precise control of the fl uence is required to avoid cracking phenomena in the stroma. (C) 1996 Wiley-Liss, Inc.