Optic Neuritis in Temporal Association With Cosmetic Hyaluronic Acid Injection: A Case Requiring Differentiation From Ischemic Optic Neuropathy.

Visual impairment following cosmetic facial hyaluronic acid injection is frequently attributed to ischemic etiologies, but non-ischemic causes can make the diagnosis challenging. We report a case of optic neuritis that developed after hyaluronic acid injection. A 27-year-old woman developed painless visual loss and a visual field defect in the left eye several days after cosmetic hyaluronic acid injection in both cheeks. The symptoms progressed over approximately two weeks, and she was referred to our hospital. Visual acuity was 1.2 in the right eye and 0.15 in the left eye. A left relative afferent pupillary defect was present. Goldmann perimetry (GP) demonstrated a central scotoma and peripheral visual field constriction in the left eye. Fundus examination showed no abnormalities. Contrast-enhanced magnetic resonance imaging (MRI) of the left optic nerve showed hyperintensity on short tau inversion recovery (STIR) and enhancement on gadolinium (Gd)-enhanced fat-suppressed T1-weighted images. Blood tests showed no systemic inflammation, and both anti-aquaporin-4 (AQP4) and anti-myelin oligodendrocyte glycoprotein (MOG) antibodies were negative. The patient was diagnosed with left optic neuritis. She received three courses of intravenous methylprednisolone pulse therapy, followed by intravenous immunoglobulin therapy. Best-corrected visual acuity in the left eye improved to 0.7 at two months and 0.9 at four months after onset. In this case, a direct relationship between hyaluronic acid injection and optic neuropathy could not be established. However, when visual loss develops after cosmetic procedures, the differential diagnosis should include not only the commonly reported ischemic disorders but also inflammatory optic neuropathy.