Ocular Syphilis in the Era of Resurgence: Clinical Characteristics and Diagnostic Challenges in a Single-Center Cohort.

Background and Objectives: The global resurgence of syphilis has been accompanied by an increasing number of ocular syphilis cases. Ocular syphilis can occur at any stage of infection and has diverse clinical manifestations, making diagnosis challenging. Materials and Methods: We retrospectively reviewed 21 adults diagnosed with ocular syphilis at a tertiary referral center between 2018 and 2023. Diagnosis was based on compatible ophthalmologic findings, together with positive treponemal serology. Demographic, clinical, ophthalmologic, laboratory, cerebrospinal fluid (CSF), imaging, and treatment data were analyzed. Results: A total of 21 patients (30 eyes) were included. The majority were male (87%), with a median age of 44 years, and bilateral involvement occurred in 43% of patients. Blurred vision and decreased visual acuity were the most common presenting symptoms (80%). Uveitis (68.4%), predominantly posterior, and optic neuritis (42.1%) were the most frequent ophthalmologic findings. Serum VDRL was negative in 5 of 21 patients despite positive treponemal serology. Among the 14 patients who underwent lumbar puncture, half had normal cerebrospinal fluid findings. All patients received neurosyphilis-directed antimicrobial therapy. The mean baseline BCVA was 0.38 ± 0.30 logMAR (range, 0-1), improving to 0.16 ± 0.28 logMAR (range, 0-1) at the final follow-up. The improvement in BCVA following treatment was statistically significant (p < 0.001). No eye showed deterioration in BCVA after treatment; visual acuity either improved or remained stable in all eyes. Additionally, all cases of uveitis and optic neuropathy achieved clinical remission during follow-up. Conclusions: Ocular syphilis remains a diagnostic challenge because of its heterogeneous clinical manifestations and the occurrence of negative serum VDRL results or normal cerebrospinal fluid findings in patients who underwent lumbar puncture. These findings highlight the limitations of relying solely on non-treponemal serology or cerebrospinal fluid analysis when evaluating patients with suspected ocular syphilis.