Transient Visual Obscurations and Systemic Symptoms Unveiling Glial Fibrillary Acidic Protein Astrocytopathy.

Introduction: Glial fibrillary acidic protein (GFAP) astrocytopathy is a rare autoimmune central nervous system disorder defined by GFAP-IgG antibodies in cerebrospinal fluid (CSF). Optic disk edema is reported in up to half of cases, but detailed ophthalmic descriptions remain limited. Case Presentation: A 68-year-old man presented with transient visual obscurations in his right eye, triggered by postural changes. His history included fatigue, weight loss, tremor, vertigo, and progressive cognitive decline, for which he had already been evaluated by multiple specialists. Ophthalmologic examination demonstrated a reduced visual acuity (0.4 right eye; 0.7 left eye), diffuse sensitivity loss on perimetry, and bilateral optic disk edema. CSF analysis showed pleocytosis and elevated protein with normal opening pressure. MRI of the brain revealed subtle radial perivascular enhancement, and MRI of the spinal cord showed lesions compatible with myelitis. GFAP-IgG antibodies were detected in CSF, confirming the diagnosis. High-dose intravenous methylprednisolone resulted in rapid clinical improvement, with complete resolution of optic disk edema and radiological abnormalities. Conclusion: GFAP astrocytopathy should be considered in patients with unexplained bilateral optic disk edema, particularly in combination with encephalitis or myelitis and negative aquaporin-4/MOG antibodies. CSF testing for GFAP-IgG is essential for diagnosis. Prompt corticosteroid therapy often leads to marked clinical improvement. Comprehensive oncological screening remains mandatory, given that concomitant neoplasms are associated with an increased risk of relapse. In such cases, long-term immunotherapy should be considered.