The purpose of Performance Standards (PS) is to provide a basis by which proposed similar or modified test methods, both proprietary (i.e., copyrighted, trademarked, or registered) and non-proprietary, can be deemed to be structurally and mechanistically similar to a Validated Reference Method (VRM) as well as can be shown to be scientifically valid, with sufficient reliability and relevance for the specific testing purposes. This document describes the Performance Standards (PS) for the assessment of proposed similar or modified methods to the Vitrigel Eye Irritancy Test Method included in TG 494.