The Isolated Chicken Eye  (ICE) test method is an in vitro test method that can be used to classify substances as "ocular corrosives and severe irritants". The ICE method uses eyes collected from chickens obtained from slaughterhouses where they are killed for human consumption, thus eliminating the need for laboratory animals. The eye is enucleated and mounted in an eye holder with the cornea positioned horizontally. The test substance and negative/positive controls are applied to the cornea. Toxic effects to the cornea are measured by a qualitative assessment of opacity, a qualitative assessment of damage to epithelium based on fluorescein retention, a quantitative measurement of increased thickness (swelling), and a qualitative evaluation of macroscopic morphological damage to the surface. The endpoints are evaluated separately to generate an ICE class for each endpoint, which are then combined to generate an Irritancy Classification for each test substance.