Herpes zoster ophthalmicus (HZO) is a condition describing the reactivation of latent varicella zoster virus (VZV) in the ophthalmic branch of the trigeminal nerve.
Risk factors for herpes zoster ophthalmicus include the following:
- Increasing age: usually in patients above 50 years of age. This is most likely because of age related immunological decline.
- Trauma to the facial region: This can precipitate a reactivation of the varicella zoster virus(VZV).
- Immuno-compromised patients: These includes patients on corticosteroid therapy, immunosuppresive chemotherapy (for patients on organ transplant or undergoing treatment for haemopoietic malignancies) or patients infected with human immunodeficiency virus(HIV).
It is usually initially characterized by:
- presence of vesicular rashes along the dermatomal distribution of the trigeminal nerve. Rashes appear on one half of the face and forehead and may or may not involve the eyes.
- the development of rash on the tip of the nose. This is a pathognoimic sign of herpes zoster ophthalmicus. It usually indicates the involvement of the nasocilliary nerve and is a strong risk factor for ocular involvement. This sign is known as Hutchinson’s sign.
The complications of herpes zoster ophthalmicus include:
HZO can lead to conditions such as conjunctivitis, keratitis, episcleritis, and anterior uveitis; all of which are likely to present with red-eye. A very strong differential of keratitis, in this case, is dendritic ulcer keratitis caused by herpes simplex virus.
Keratitis, a condition characterized by inflammation of the eye’s cornea, caused by herpes simplex, would present with a dendritic ulcer on slit-lamp fluorescein examination of the affected eye. So if you see a dendritic ulcer in the eye, think of herpes simplex, not herpes zoster.
Ptosis refers to a drooping eyelid where the upper eye area lowers downward. This happens because herpes zoster paralyzes the oculomotor nerve or one of its branches. So the presence of ptosis in one eye with vesicular rashes is an indication of herpes zoster ophthalmicus.
Postherpetic Neuralgia (PHN)
Postherpetic neuralgia is the most common complication of shingles. Please note that herpes zoster ophthalmicus is simply ophthalmic shingles. In postherpetic neuralgia, the virus affects nerve fibers, causing burning pain that lasts long after the rash and blisters of shingles disappear.
The pain associated with PHN could be burning, stinging, sharp, shooting, or jabbing. The patient could also experience deep throbbing and aching pain.
Ocular involvement will require urgent ophthalmic review. This is to prevent loss of vision which could occur in HZO.
Key management involves the administration of oral antiviral drugs like Famciclovir and aciclovoir as well as administration of corticosteroids. The corticosteroids will help reduce the inflammation.