Solid state lasers for ocular surgery: preclinical study

The erbium laser could provide an interesting solid state alternative to the excimer laser (193 nm) for photokeratectomy. The very high absorption of the erbium laser radiation (2.94 micrometers ) by water leads to precise excisions in the cornea with limited thermal damage. In this work we have studied the effects of Q-switch erbium pulses on rabbit eyes. An ultra-fast imaging technique, based on an intensified video camera and on a nitrogen pumped dye laser, was used to investigate the dynamic evolution of the plume during the laser interaction. During the interaction with eyes deprived of the epithelium the ratio between vapor and fragments in the plume strongly depends on the hydration of the stroma. Histologic analysis was carried out to estimate the quality of incision and the amount of thermal damage.