Atypical Presentation of Optic Neuritis in a Patient with Active Hepatitis C Infection: A Case Report

Background/Objectives: Optic neuritis is associated with demyelinating diseases such as multiple sclerosis (MS), but atypical presentations, particularly bilateral optic nerve involvement or coexisting systemic symptoms, necessitate broader diagnostic consideration. Case presentation: This case report describes a 50-year-old male with untreated, active hepatitis C virus (HCV) infection who presented with bilateral optic neuritis. Cerebrospinal fluid (CSF) analysis revealed elevated myelin basic protein, positive oligoclonal bands, an elevated immunoglobulin G index, and an HCV viral load of 9.3 million international units/milliliter (IU/mL). Magnetic resonance imaging (MRI) of the orbits showed bilateral optic neuritis with perineuritis. The patient had no history of interferon therapy and lacked markers of cryoglobulinemia, making this a rare case of optic neuritis possibly associated with chronic hepatitis C viral infection. The patient was treated with intravenous immunoglobulin (IVIG) without corticosteroids, with some improvement in vision. Conclusions: This case adds to the expanding spectrum of multiple sclerosis (MS) mimics and underscores diagnostic challenges associated with atypical optic neuritis presentations, particularly in the setting of coexisting systemic viral infections.