acute and superficial, involving the corneal epithelium and possibly up to one-third of the anterior stroma (FIGURE 2). To the naked eye, these ulcers may not be noticeable, but they take up fluorescein stain. Corneal edema is generally absent to mild, and neovascularization is not present. Although simple ulcers are probably contaminated with microorganisms, deep infection has not yet occurred.10