Three main types of herpes simplex keratitis are Epithelial keratitis (dendritic keratitis) Disciform keratitis (localized endotheliitis) Stromal keratitis Reactivation of latent herpes simplex can be triggered by UV light exposure (eg, intense sunlight, corneal cross-linking [an ultraviolet light treatment that stiffens the cornea], or laser refractive procedures), fever, menstruation, significant systemic physical stress (eg, burns or multiple fractures), immunosuppression, or use of glucocorticoids (topical ophthalmic, periocular injection, intraocular injection, or systemic).