A Rare and Complex Diagnostic Challenge: Herpes Zoster Ophthalmicus With Secondary Orbital Apex Syndrome in a 65-Year-Old Male.

Herpes zoster (HZ) results from the reactivation of the varicella zoster virus (VZV) in sensory ganglia, with immunosuppression and aging being major risk factors. A subtype, HZ ophthalmicus (HZO), involves the ophthalmic division of the trigeminal nerve and can lead to significant ocular complications. Orbital apex syndrome (OAS), a rare condition involving multiple cranial nerve dysfunction due to involvement of the orbital apex, may complicate HZO. A 65-year-old male with a history of type 2 diabetes mellitus, benign prostatic hyperplasia, migraines, and bipolar disorder presented with a two-day history of a severe right retro-orbital headache, lacrimation, nausea, dizziness, and photophobia. Initial work-up suggested a cluster headache. However, he developed a vesicular rash on the right side of his forehead, along with a swollen right eyelid and red eye. On the fourth day of admission, a diagnosis of HZO and OAS was made, and antiviral therapy with intravenous acyclovir and methylprednisolone was added to his pain management regimen. OAS is a rare but severe complication of HZO, characterized by painful ophthalmoplegia, vision loss, and cranial nerve dysfunction. If left untreated, OAS can be fatal if it involves the cavernous sinus. The diagnosis is confirmed through clinical examination and neuroimaging, which may reveal orbital myositis, optic nerve abnormalities, and perineural enhancement. OAS can be precipitated by comorbidities such as diabetes, and its onset typically occurs 10-14 days after the rash. Treatment consists of analgesics, antiviral therapy, and corticosteroids. Early recognition and aggressive management are essential to prevent long-term complications, such as postherpetic neuralgia and permanent vision loss.