Diagnosis of syphilitic chorioretinopathy in a patient with a history of relapsing-remitting multiple sclerosis and previous optic neuritis

Syphilis can present with diverse ocular manifestations, including optic nerve and retinal involvement, often mimicking inflammatory or demyelinating disorders. In patients with pre-existing demyelinating conditions, new visual symptoms are frequently attributed to demyelination, which may delay recognition of coexisting syphilitic eye disease. We report a man in his 40s with relapsing-remitting multiple sclerosis who developed sequential central scotomas without pain on eye movements or dyschromatopsia. Examination revealed bilateral vitreous cells, and optical coherence tomography (OCT) showed ellipsoid zone disruption. Serologic testing demonstrated a reactive rapid plasma reagin titre of 1:64, confirming syphilitic chorioretinopathy. Treatment with intravenous penicillin led to marked visual improvement and restoration of the ellipsoid zone on OCT. This underscores the need to consider syphilis in the differential diagnosis of optic neuritis, even in patients with known demyelinating disease, and highlights the value of thorough ophthalmic evaluation and OCT imaging in such presentations.