A Case of Syphilitic Outer Retinitis Mimicking Acute Zonal Occult Outer Retinopathy

Dear Editor, Syphilis is a sexually transmitted, systemic infection with increasing prevalence. Ocular syphilis may develop at any stage of the disease process and can involve any ocular structure [1]. Ocular syphilis mimics any type of inflam-matory process without pathognomonic manifestations and often leads to misdiagnosis, resulting in permanent vision loss [1,2]. Syphilitic uveitis involving the posterior segment has been reported as several conditions [1]; however , to our knowledge, no previous study describing syph-ilitic outer retinitis has examined the condition by spectral domain optical coherence tomography (SD-OCT). Herein, we report a case of syphilitic outer retinopathy, mimicking acute zonal occult outer retinopathy (AZOOR). A 59-year-old man presented with a 2-week history of blurred vision in the right eye. Visual acuity was 20 / 30 in right eye and 20 / 20 in left eye. Slit-lamp examination and fundoscopy were normal (Fig. 1A). Fundus fluorescein an-giography showed no abnormality in early and late phases (Fig. 1B). However, fundus autof luorescence imaging showed hyperfluorescence around the macula, while SD-OCT revealed a diffuse disruption of the photoreceptor inner segment-outer segment (IS-OS) junction line in the macula in the right eye (Fig. 1C and 1D). Multifocal elect-roretinography (ERG) revealed reduced amplitudes in the centermost and inferior retinal areas which corresponded to the area of visual field defect on Humphrey visual field (HVF) perimetry, and to the area of disrupted photorecep-tors at the IS-OS junction line on SD-OCT (Fig. 1E and 1F). Full-field ERGs were normal and symmetric. The pa-tient's medical history and laboratory tests were unremark-able; serologic tests for syphilis were not performed. We initially diagnosed him with AZOOR, based on acute loss of visual acuity, fundoscopy, and ERG findings [3]. The patient received 15 mg/day oral prednisolone for 1 month, which was then tapered to 10 mg/day for 2 months. Since vision improved to 20 / 25 and photoreceptor disruption was partially restored after treatment (Fig. 1G), we added oral methotrexate (15 mg/wk). However, at 5 months, vision decreased to 20 / 30, vitreous opacity developed, and photoreceptor disruption progressed on SD-OCT (Fig. 1H). At 6 months, the photoreceptor disruption worsened and his vision deteriorated to 20 / 50 (Fig. 1I). Complete serologic tests were performed, which diagnosed him as active syphilis (both the Venereal Disease Research Laboratory assay and fluorescent treponemal antibody-absorption test were positive). We diagnosed him with syphilitic outer retinopa-thy in right eye and discontinued immunosuppressant therapy and intramuscularly …