Keratolenticular dysgenesis (Peters' anomaly) was induced in mice by exposure to the human teratogens, ethanol or 13-cis retinoic acid (isotretinoin, Accutane). Acute teratogen exposure on the seventh day of gestation (corresponding to the third week of human gestation) resulted in an eye malformation incidence of 46% to 100% in day 14 fetuses. Of the abnormal eyes, 10% to 29% demonstrated failure of detachment of the lens from the surface ectoderm. Delayed lens detachment was seen as anterior lenticonus in 33% to 35% of the abnormal eyes. Abnormal lens detachment appeared to result in mechanical interference with neural crest migration to form the corneal stroma and endothelium, and iris stroma. This secondary effect on neural crest derivatives is exhibited in the adult animals as corneal opacities associated with defects in Descemet's membrane and endothelium, and anterior polar cataracts.