[The ablation behavior of various corneal layers].

The difference in structure of the corneal layers leads to an inhomogeneous reaction to photoablation with 193 nm excimer laser light. This is important for the calculation of photorefractive keratectomy (PRK) where only a thin layer (10-50 microns) of the cornea must be removed. Therefore, the ablation rate for the Bowman zone is 2.5 times lower than that for corneal stroma; the same value is found in Descemet membrane. In contrast, the ablation rate of the epithelium is 1.5 times higher. Based on these data it will be possible to achieve high precision with PRK.