Studies in the basic and clinical sciences have yielded new information about the biology, infection, latency, and recurrence of the varicella-zoster virus. Contrast is made with the herpes simplex virus. The host-viral relationship is an extremely dynamic one with clinical disease being determined primarily by the host cellular immune system. The complications of herpes zoster ophthalmicus are related to multiple mechanisms including viral growth, vascular and neural damage, and the host-immune response to infection. There are several laboratory tests available for confirming the diagnosis or determining the immune status. Systemic acyclovir administered early in the course alleviates many of the symptoms of herpes zoster ophthalmicus. Acute and postherpetic neuralgia remain significant and enigmatic problems; an update of therapeutic options is offered. The role of corticosteroids in herpes zoster ophthalmicus is scrutinized along with the potential and uncertainties of a varicella-zoster virus vaccine.