Syphilis is a sexually transmitted infection (STI) caused by the bacterium Treponema pallidum (a spirochete) and is characterized by a chronic, intermittent clinical course. Treponema pallidum is transmitted person to person via mucous membranes or through direct contact with a syphilis ulcer during vaginal, anal, or oral sex.

There are 4 main stages of syphilis: primary, secondary, latent, and tertiary. Active infection stages include primary, secondary, and early latency. Tertiary syphilis has a later onset in patients who never received initial treatment. Tertiary syphilis can include cardiac or neurologic manifestations known as neurosyphilis. Syphilitic uveitis or other ocular syphilis manifestations (eg, neuroretinitis and optic neuritis) can occur at any stage of syphilis and can be isolated abnormalities or associated with neurosyphilis. 

All structures of the eye may be involved by syphilis, which is why it has been named the great imitator. Manifestations can include conjunctivitis, scleritis, episcleritis, keratitis, glaucoma, ocular motility disturbances, ptosis, pupillary changes, lens dislocation, uveitis, vitritis, chorioretinitis, or optic atrophy. Patients may present with vision changes (eg, vision blurring or dimming, impaired color perception, photophobia) and decreased visual acuity that can progress to permanent blindness. Some ocular manifestations may occur years after initial involvement.

Ocular syphilis can be congenital or acquired. Congenital syphilis, despite its relative rarity, still poses a very significant threat to the eye. 

If ocular syphilis is suspected, immediate referral to and management in collaboration with an ophthalmologist is crucial. Ocular syphilis should be treated similarly to neurosyphilis, even if a cerebrospinal fluid (CSF) examination is normal.

Prognosis is variable and depends on at what stage the disease was treated and what ocular structures have been affected. Anterior uveitis and retinal vasculitis usually have good prognoses. Poorer prognostic factors include coinfection with HIV, associated optic neuropathy, or poor vision at the time of diagnosis.

Related topics: early and late congenital syphilis, primary syphilis, secondary syphilis, neurosyphilis