Iberian Registry of Ocular Syphilis (IBERSOS) report 1: epidemiology, clinical spectrum and treatment outcomes of ocular syphilis in the Iberian Peninsula

Purpose The Iberian Registry of Ocular Syphilis aims to describe the epidemiology, clinical manifestations and treatment outcomes of ocular syphilis in Spain and Portugal. This re-emerging condition, associated with rising global syphilis rates and HIV coinfection, presents with diverse ocular and systemic features. The study seeks to fill knowledge gaps regarding incidence, presentation and therapeutic response. Methods This multicentre, observational cohort study includes patients aged ≥18 years with newly diagnosed ocular syphilis confirmed by treponemal and nontreponemal serological tests. Conducted across 23 centres, data collection followed routine clinical practice and included demographics, ocular/systemic findings, treatment regimens and outcomes at 3–6 months post-treatment. Results In the first year, 41 patients met the inclusion criteria, of whom 39 consented to participate in the registry, with an incidence of 0.57 cases per 100 000 persons/year. Most were male (94.9%), especially men who have sex with men (66.7%) and HIV coinfection (20.5%). Bilateral ocular involvement was observed in 64.1% of patients, with anterior segment inflammation in 64.1%, vitritis in 53.8%, retinal or choroidal involvement in 69.2% and optic nerve involvement in 59.0%. Systemic syphilis stage included primary (7.7%), secondary (25.6%) and tertiary or quaternary (15.4%). Treatment was initiated after a mean of 6.2±9.3 weeks after the onset of symptoms, and 2.6±6.0 weeks after the initial presentation at the hospital. Intravenous penicillin G was used in 65.8%, and 61.3% achieved a four-fold titre reduction in the reaginic test at the final visit (3 to 6 months after antibiotic therapy). Final visual acuity improved to 0.17 LogMAR (p<0.001), with 56% of eyes gaining ≥0.1 LogMAR. Conclusions Ocular syphilis in the Iberian Peninsula shows a wide clinical spectrum and frequent posterior segment involvement. Most patients achieved favourable serological and visual outcomes. These findings support the effectiveness of standard therapies and highlight the need for early diagnosis, especially in high-risk populations.