To report a case of ocular syphilis presenting as bilateral optic neuritis.

A 25-year-old man presented with visual difficulty in both eyes that had begun 2 weeks previously. Best corrected visual acuity was 0.7 in the right eye and 0.1 in the left eye. Anterior segment was normal. On fundoscopic examination, optic disc swelling was found in both eyes. Color vision was abnormal in the left eye. The visual field (VF) showed peripheral constriction in the right eye and generalized reduction in the left eye. Fluorescein angiography revealed early, bilateral leakage of dye from the optic disc with multiple hot spots in the chorioretinal level. Serology was positive for fluorescent treponemal antibody absorbance (FTA-ABS) IgM, IgG and rapid plasma reagin test. A test of the cerebrospinal fluid was positive for venereal diseases research laboratory and FTA-ABS IgG. A diagnosis of syphilitic optic neuritis was made and the patient was treated with antibiotics. Six months later, visual acuity was 1.0 in the right eye and 0.8 in the left eye. There was no disc swelling on both fundoscopy and optical coherence tomographs. VF also improved after treatment, with the restoration of central vision.

Syphilis can present as optic neuritis. Clinicians should consider serologic examination for syphilis and then initiate appropriate antibiotic treatment.