Despite the availability of antiviral agents that are effective in treating herpes simplex epithelial keratitis, inflammation in the corneal connective tissue and iris that can lead to corneal scarring and visual impairment develops in many patients. Prior to the HEDS-I trials, the role of topical corticosteroids in the management of HSV stromal keratitis was uncertain; some animal and human studies suggested there was a benefit to treatment whereas others suggested harm. The value of adding an oral antiviral agent to treatment with topical corticosteroids and topical antivirals also was unknown.