Unilateral acute retinal necrosis occurring 2 years after herpes simplex type 1 encephalitis

Acute retinal necrosis (ARN) syndrome is known to occur occasionally in association with or shortly after herpetic encephalitis. We describe a patient with unilateral ARN occurring 2 years after herpes simplex virus (HSV) type 1 encephalitis. A 49-year-old man presented with unilateral visual loss. He had a history of HSV-1 encephalitis 2 years previously, and had been successfully treated without a subsequent recurrence. The ophthalmologic findings were all consistent with the ARN syndrome. The same type 1 HSV was identified from ocular fluid as was identified from the patient's cerebrospinal fluid 2 years ago. There was no evidence of a recurrence of encephalitis. This case suggests that following encephalitis retinal neurons may function as a reservoir for latent HSV-1, that can be reactivated to cause ARN in situ several years later.