Secondary syphilis presenting with acute unilateral vision loss and a widespread maculopapular rash

Syphilis infection has shown a marked resurgence over the past several years. Ocular involvement is a rare complication of syphilis, occurring in approximately 1% of cases. We present the case of a man in his 50s who presented to hospital with acute unilateral vision loss and a widespread maculopapular rash. Ophthalmological examination showed unilateral optic disc swelling and bilateral vitritis. Intracranial imaging revealed no acute pathology. Initial blood tests were normal apart from mildly elevated inflammatory markers. A comprehensive autoimmune and infection screen revealed positive syphilis serology. The patient was subsequently treated for syphilis with ocular involvement with a course of intravenous benzylpenicillin, resulting in rapid symptomatic improvement. This case highlighted the importance of considering syphilis infection as part of the differential diagnosis for unexplained multisystemic symptoms, such as loss of vision in combination with dermatological involvement.