Herpes Zoster Ophthalmicus Complicated by Orbital Apex Syndrome.

A 63-year-old male with type 2 diabetes developed herpes zoster ophthalmicus (HZO), initially presenting with a left-sided headache and eyelid itching. He was misdiagnosed with cluster headache but later returned with a vesicular rash, prompting treatment with IV acyclovir. He later exhibited ptosis, diplopia, and vision loss in the left eye. Examination revealed proptosis, ophthalmoplegia, RAPD, and corneal anesthesia. MRI revealed enhancement of the left extraocular muscles and optic nerve sheath, consistent with orbital apex syndrome (OAS). Lumbar puncture confirmed varicella zoster virus involvement, and repeat imaging revealed CNS vasculitis and a subacute thalamic infarct. The patient was treated with antivirals, IV steroids, and antiplatelet therapy. Visual acuity and motility improved significantly post-treatment. This case highlights the rare but serious complication of OAS secondary to HZO. OAS involves dysfunction of multiple cranial nerves and may mimic other orbital syndromes but is distinguished by optic nerve involvement. Prompt recognition and aggressive treatment are critical to prevent permanent visual and neurological deficits in HZO-associated OAS.