Herpes zoster ophthalmicus is not an uncommon disease and is more prevalent among debilitated and seriously ill patients. It is caused by the same virus causing varicella. The exact trigger mechanism is unknown, as well as much of the pathogenesis. The disease is more uncommon among the elderly and usually runs a benign course. Approximately 50% of the patients develop ocular complications ,the most frequent of these being keratitis, iritis, secondary glaucoma and extraocular muscle involvement. The most striking pathologic features are the lymphocytic infiltration of the long ciliary nerves and the vasculitis of the vessels accompanying them. The most controversial aspect of the disease is that of treatment. Almost every therapeutic regimen has been attempted in a disease whose natural course is self-limited. The future will add more to our knowledge of the pathogenesis of the disease and shed more light on the efficacy of various treatments.