Atypical ocular syphilis presenting as anterior uveitis: clinical response to oral doxycycline in a non-adherent patient.

BACKGROUND

Ocular syphilis is a rare but potentially sight-threatening manifestation of Treponema pallidum infection, characterized by highly variable clinical presentations and diagnostic challenges.

CASE PRESENTATION: A 27-year-old male presented with widespread maculopapular rash, headache, and visual impairment. Ophthalmological examination revealed bilateral anterior uveitis with posterior synechiae and near-complete vision loss in the right eye. Serological testing confirmed syphilis (RPR 1:8), while cerebrospinal fluid (CSF) analysis showed positive FTA-ABS and negative VDRL. Intravenous penicillin G was initiated, resulting in early clinical improvement; however, the patient discontinued treatment due to poor adherence. Subsequent ceftriaxone therapy failed to achieve adequate response. Owing to non-adherence to parenteral regimens, oral doxycycline was initiated, leading to clinical and serological improvement. No relapse was observed during 3 months of follow-up.

CONCLUSION

This case highlights the diagnostic complexity and variable presentation of ocular syphilis, particularly when presenting as anterior uveitis. Discordant CSF findings should not exclude the diagnosis. Treatment adherence remains a critical challenge, and doxycycline may represent a potential alternative in selected non-adherent patients.