Herpes zoster is a not rare acute infection of the posterior root ganglions with signs in the segmental distribution of the nerve roots involved,1 while, contrariwise, herpes zoster ophthalmicus, or herpes zoster of a gasserian ganglion, a homologue of a posterior root ganglion, is apparently a rather rare disease; indeed, it is so rare that Rice2 stated that no cases of ophthalmic herpes zoster were mentioned, for example, in the report of one of the largest ophthalmologic and otologic hospitals in the United States, in which over 100,000 patients with ocular disease were treated in 1922. On the other hand, Gundersen,3 in searching for cases of herpes zoster ophthalmicus, found 10 per annum at the Massachusetts Eye and Ear Infirmary, in Boston, over a five year period. From the standpoint of the dermatologist, who will inevitably see ophthalmic herpes zoster initially, the common sites of localization of