When the characteristic rash appears, a diagnosis of herpes zoster ophthalmicus is easily made. However, there is more to this condition than what usually meets the eye.
Herpes zoster ophthalmicus results from reactivation of latent varicella zoster virus affecting the ophthalmic branch of the trigeminal nerve. The reactivation is caused by a decline in the cellular immunity response, and onset may follow trauma or periods of stress, which are correlated with a decline in cell mediated immunity. Herpes zoster ophthalmicus may also follow chemotherapy for malignant disease.