A 69-year-old man with left eye pain and visual impairment was diagnosed with syphilitic optic neuritis, who was successfully treated by penicillin. Although it is difficult to decide syphilis as the direct cause of optic neuritis, it is essential to diagnose syphilis in every patient with optic neuritis.
Keywords: impaired visual acuity; magnetic resonance imaging; rapid plasma regain; syphilitic optic neuritis; treponema pallidum hemagglutination assay.
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