Assessment of Syphilitic Optic Neuropathy: A Prospective Cross-Sectional Study

To evaluate the clinical features of syphilis optic neuropathy (SON) and explore its underlying pathogenesis by measuring the peripapillary retinal nerve fiber layer (pRNFL). This was a prospective cross-sectional study. Syphilitics, regardless of ocular complaints, in the ophthalmology department in 2020 were screened for SON, which was defined as isolated optic neuropathy without overt signs of syphilitic uveitis. We analyzed the demographic and clinical information, including ultra-wide-field fundus photographs, fundus fluorescein angiography (FFA), and pRNFL thickness measured by spectral-domain-OCT (SD-OCT). Of 577 cases with syphilis, 25 patients (4.3% ± 0.8%) presented with optic disc edema and 7 patients (1.2% ± 0.5%) with optic atrophy. Of the eyes with optic disc edema, (35 eyes, 40% biocular), 40% had no ocular symptoms, and 45.7% had visual acuity (VA) better than 20/25, whereas 100% showed optic disc leakage in FFA. Of the eyes with optic atrophy (14 eyes, 100% biocular), 100% were male and presented severe vision impairment (VA worse than 20/70), but no optic disc leakage in FFA. A higher rapid plasma reagin (RPR) level was more frequently observed in patients with SON (p = 0.009). Additionally, the pRNFL thickness in non-ocular syphilis was not related to the RPR level or the syphilis duration (all p > 0.05). The SONs could manifest as asymptomatic optic disc edema or blinding optic atrophy, which were independent episodic reactions from ocular or cerebral syphilis, respectively. Our data highlighted the need for ophthalmic screening and prompt neurosyphilis treatment.