Unilateral Syphilitic Optic Neuritis without Uveitis

Abstract

This report describes a case of case of unilateral syphilitic optic neuritis without uveitis. A 56-year-old man presented with complaints of four days history of decreasing vision in his left eye. At the initial visit, the patient’s best corrected visual acuity was 1.2 and 0.03 in the right and left eye, respectively. A relative afferent pupillary defect was observed in the left eye. Slit-lamp examination revealed no cells, flare or keratic precipitates in the anterior segment either eye. Fundoscopy revealed diffuse optic disc swelling with peripapillary hemorrhage in the left eye. Goldmann visual field testing identified central absolute scotoma and an enlarged blind spot in the left eye. On serological evaluation for syphilis, serum rapid plasma reagin (RPR) and treponema pallidum hemagglutination assay (TPHA) were positive (RPR 52.5, TPHA 740.0). In addition, IgM fluorescent Treponemal antibody absorbance (FTA-ABS) was positive. In contrast, cerebrospinal fluid showed negative RPR and positive TPHA (TPHA 11.8). Cerebrospinal fluid (CSF) analysis showed lymphocytic pleocytosis and increased protein content and glucose. Magnetic resonance imaging showed a swollen enhanced lesion in the left optic nerve. The patient was diagnosed with syphilitic optic neuritis and received the currently recommended treatment with intravenous penicillin G (PCG). Twenty-four million units per day of PCG were administered for 2 weeks. After 2 weeks of therapy, his left visual acuity improved to 0.3 in 2 months. However, the optic disc looked diffusely pale in the left eye. At 6-month visit, the patient was clinically stable. RPR turned out negative and there was a reduction in serological TPHA reactivity. We consider that it is essential to perform serological tests for syphilis in every patient with optic neuritis, which makes it possible to initially treat syphilitic optic neuritis with PCG.