RESUMO
Syphilis is a rare cause of vision loss that mostly occurs after an infection of the meninges, brain tissue, and parenchyma. Syphilis can mimic auto-immune disease like giant cell arteritis which also manifest as sudden vision loss. Spirochete Treponema pallidum can spread through sexual contact and cause painless ulcers. Spirochetes can disseminate systemically and lead to secondary syphilis. Ocular syphilis can affect all parts of the eye in secondary and tertiary stages. It can present as scleritis, inflammation of the optic nerve, and uveitis. We present the case of a 59- year-old male suffering from severe vision loss in the left eye and headache initially misdiagnosed with giant cell arteritis. He was correctly diagnosed with ocular syphilis after seeing a red macular rash on palms and soles, and was given penicillin G and probenecid. His visual acuity and field of vision improved soon. Ocular syphilis is usually diagnosed late or misdiagnosed and leads to irreversible vision loss. Physicians should keep in mind the possibility of ocular syphilis in patients presenting with a sudden loss of vision and severe headaches.