Delayed Nonarteritic Posterior Ischemic Optic Neuropathy following Herpes Zoster Ophthalmicus: A Case Report

Posterior ischemic optic neuropathy (PION), a relatively rare condition, is diagnosed primarily based on the clinical presentation of sudden visual impairment, an optic nerve-related visual field defect, and an initial normal optic disc that corresponds to its pathology of acute ischemia. Among its etiologies, nonarteritic PION is one of the most common causes. Studies on cases of PION associated with herpes zoster ophthalmicus (HZO) are limited, and the diagnosis was made based on the appearance of visual symptoms shortly following rashes. We describe a 64-year-old Asian woman with sudden painless visual loss in the upper half visual field of the left eye 6 weeks after ipsilateral HZO. Within a week, her left vision progressed to total visual loss. Initial examination revealed a near-total visual defect and a normal appearance of the optic disc in the left eye. Laboratory and imaging studies excluded the compressive, infiltrative, or inflammatory etiologies of the left optic nerve. Considering the temporal relationship between the skin rash and visual loss, HZO was the most likely cause of the nonarteritic PION. The patient was given a short course of oral valaciclovir and aspirin. At 6 weeks after the visual loss, an examination revealed stationary visual acuity and visual field defect in the left eye with a pale optic disc, and a retinal nerve fiber loss in the left eye. Compared with previous studies, our case demonstrated a delayed presentation of nonarteritic PION following HZO and broadened the scope of herpes zoster optic neuropathy.