Fluorescence spectra of human, bovine and porcine corneas were measured under 193 nm excimer laser irradiation. Secondary radiation occurs in the mutagenic range between 260 and 290 nm. In situ measurements via a quartz fiber introduced into the eye to the lens surface showed that secondary radiation in the cataractogenic range between 295 and 320 nm is transmitted by the cornea and reaches the lens. The potential adverse effects of this secondary radiation should be considered when applying 193 nm excimer laser radiation to the cornea.