British Ocular Syphilis Study (BOSS): 2-year National Surveillance Study of Intraocular Inflammation Secondary to Ocular Syphilis

Purpose: The British Ocular Syphilis Study (BOSS) is the first national prospective epidemiological study of intraocular syphilis (IOS) in light of the global increase in early syphilis (ES). The aims were to ascertain the UK incidence, demographics, clinical features, laboratory data, and posttreatment visual outcomes of patients with IOS.

Methods: Prospective study of IOS, reported through the national reporting system (British Ocular Surveillance Unit) from 2009 to 2011. Case definition was any adult presenting with intraocular inflammation in ES.

Results: A total of 41 new cases (63 eyes) of IOS were reported, giving an annual incidence of 0.3 per million UK adult population. Mean age was 48.7 years (range, 20.6-75.1); 90.2% were male. All had RPR/VDRL titers of ≥1:16. Bilateral ocular involvement occurred in 56%; in unilateral cases, the left eye was more commonly affected (P = 0.009). Mean presenting logMAR visual acuity was 0.52 (20/63 Snellen; range, -0.2 to 2.30 logMAR). Panuveitis was the commonest diagnosis, seen in 41.3%, and isolated anterior uveitis was uncommon (9.5%). Subgroup analysis between HIV-positive and -negative patients found no significant differences in terms of proportion of bilateral disease, presenting or post treatment acuity. HIV-positive patients had higher rates of panuveitis. At final follow-up, 92.1% had visual acuity ≥ 0.3 logMAR (20/40 Snellen) after antibiotic therapy.

Conclusions: This study is the largest prospective series of ocular syphilis in the post-penicillin era. It confirms good visual outcomes for treated IOS, irrespective of HIV status or time to presentation. The study identified an unexpected preponderance for left eye involvement in uniocular cases; which is unexplained.