Syphilis, a chronic infectious disease caused by the bacterium Treponema pallidum, commonly involves the eyes as one of the affected organs. Its clinical presentations are diverse and may include various forms of ocular inflammation. These manifestations encompass interstitial keratitis, scleritis, uveitis, retinitis, retinal vasculitis, optic disc inflammation (papillitis), and retrobulbar optic neuritis. In cases of congenital syphilis, isolated or multifocal chorioretinitis may also occur. This condition often presents shortly after birth, typically involving both eyes. It manifests diffusely with a "pepper and salt fundus," characterized by scattered small bluish-black spots interspersed with similarly-sized depigmented lesions. Peripheral or diffuse atrophic areas of chorioretinal tissue, along with bone spicule-like pigmentary deposits, are also observed across the retinal landscape.
Syphilis has the potential to affect the optic nerve, resulting in optic neuritis or neuroretinitis, which may eventually lead to optic atrophy. Additionally, syphilis can involve the brain's vasculature and cranial nerves, causing manifestations such as strabismus, ptosis, and pupillary abnormalities. A distinctive pupillary abnormality associated with syphilis, known as the Argyll Robertson pupil, is characterized by bilateral, irregularly shaped, and asymmetrically sized pupils that are miotic (constricted). These pupils demonstrate reflex paralysis with no response to light but retain accommodation and convergence responses and exhibit reduced responsiveness to mydriatic agents.