A 55-year-old male presented with acute painless unilateral blurred vision for 3 days without discharge, photophobia and photopsia. The patient was generally healthy and had no chronic medical conditions. There was no previous history of eye diseases, trauma and surgery. The best-corrected visual acuity (BCVA) was 0.2 for the right eye and 1.0 for the left eye. Intraocular pressure was 16 mmHg in both eyes. The corneas were clear and the pupils were equally round in both eyes. The anterior segment of both eyes was normal without evidence of relative afferent papillary defect in either eye. There were no inflammatory cells in the vitreous of both eyes. In the macula, yellowish-white focal lesions of the right eye were observed (Figure 1A). Two days later, subtly changes of lesions were found along the superotemporal and inferotemporal arcades in the macula (Figure 1B) and BCVA was 0.12, while the posterior of the left eye was normal. Fluorescein fundus angiography (FFA) demonstrated (Figure 1) slight fluorescent leakage in the macula of the right eye, and segmen tal venous leakage and optic disc hyperffuorescence were observed in both eyes (Figure 1D). Indocyanine green angiography (ICGA) indicated that the lesions in the macula of the right eye had spotty hypofluorescence at early stage and the hypofluorescence was signiffcant at late stage (Figure 1E,F). Spectral domain optical coherence tomography (SD-OCT) imaging of the macula for the right eye showed focal impairment of the inner segment and outer segment (IS/OS) (Figure 2A), while OCT imaging of the macula for the left eye was normal. 
Systemic general examination and the peripheral blood showed normal. Chest X-ray and MRI of the brain were normal. Laboratory examinations showed human immunodeffciency virus (HIV) antibodies, cytomegalovirus IgM, toxoplasma IgM antibodies, and herpes simplex virus IgM antibodies were negative. C-reactive protein (CRP) and erythrocyte sedimentation rate were normal. All other autoimmune screening tests were negative. Serum glucose level was 5.9 mmol. The blood investigation indicated the peripheral blood a positive treponema pallidum hemagglutination assay (TPPA) and a rapid plasma reagin test (RPR) of 1:32. Lumbar puncture was recommended to evaluate for CSF antibodies, but the patient declined this invasive test. After the diagnosis was confirmed to be ocular syphilis, the patient was recommended a treatment of benzathine penicillin intramuscular injection of 120 million units bilaterally once a week. Two weeks after initial treatment, visual improvement to 0.2, while OCT changes persisted in right eye (Figure 2B). After anti syphilitic treatment for 6 weeks, the yellowish-white lesions had vanished (Figure 1C) and the BCVA was 1.2 followed by restoration of the IS/OS for the right eye (Figure 2C), with an RPR of 1:4.
(A) Fundus color photograph showed yellowish-white focal lesions of the right eye in the macula at presentation; (B) showed subtly changes along the superotemporal and inferotemporal arcades in the macula two days after presentation; (C) showed lesions vanished after treatment; (D) fluorescein fundus angiography (FFA) demonstrated slight fluorescent leakage in the macula of the right eye, and segmental venous leakage and optic disc hyperfluorescence were observed for both eyes; (E) indocyanine green angiography (ICGA) indicated that the lesions in the macula of the right eye had spotty hypofluorescence at early stage; (F) the hypoffuorescence was signiffcant at late stage .
(A) The impairment (white arrows) of the inner segment and outer segment (IS/OS) before treatment; (B) the impairment (white arrows) of the IS/OS persisted two weeks after treatment; (C) restoration (white arrows) of the IS/OS six weeks after treatment.

Discussion