Dr. Bennie H. Jeng presents the lecture prepared by Todd P. Margolis, MD, PhD, on differentiating varicella zoster virus (VZV) and herpes simplex virus (HSV) keratitis. Dr. Jeng covers easily recognizable differences in the visual presentations of epithelial disease, and provides pearls for making the much more difficult diagnoses for stromal cases. Though no method is foolproof, he emphasizes the importance of achieving a diagnosis because the treatment regimens differ.