Methotrexate-Induced Optic Neuropathy: A Rare and Under-Recognized Cause of Visual Loss in the Elderly.

Methotrexate (MTX) is widely used in the management of psoriatic arthritis and is generally considered a safe disease-modifying antirheumatic drug (DMARD). Although its systemic adverse effects are well established, neurotoxicity, including optic neuropathy, is exceedingly rare and often overlooked. This report describes the case of a 74-year-old man on long-term low-dose MTX who presented with progressive unilateral visual loss. Examination revealed optic disc pallor, retinal nerve fiber layer (RNFL) thinning, central scotoma, low serum folate levels, and borderline vitamin B12. Magnetic resonance imaging (MRI) excluded demyelinating or structural pathology. MTX was discontinued, and vitamin supplementation was given, stabilizing vision but with persistent optic atrophy. This case underscores the importance of clinician awareness and early ophthalmic evaluation in MTX-treated patients presenting with visual symptoms, especially those in high-risk groups.