Local tissue tolerance or irritation studies assess the short-term and generally localized hazards of medical devices in the immediate region of their tissue contact. Topical local (tissue) tolerance effects are almost entirely limited to irritation. Though this usually means dermal irritation, it can also be vaginal, muscular, vascular, mucous membrane, rectal, nasal, or ocular. All of these but ocular irritation use some version of a common subjective rating scale (see Table 8.1) to evaluate responses.