Case Presentation: A 30-year-old male with no significant past medical history presented with one year of progressive vision loss. He saw an ophthalmologist one month after the initial onset and described it as a “dark curtain” progressing from his central vision. He was diagnosed with decreased visual acuity bilaterally. He was prompted to go to the emergency room to have imaging and evaluation but elected not to seek further care. Six months after initial onset of vision loss, he was seen by his primary care physician. At that visit, he noted functional decline with inability to drive due to worsening vision changes. He underwent a neurological workup that demonstrated an elevated MMA, a RPR that was 1:32, and a positive microhemagglutination assay for Treponema pallidum antibodies (MHA-TP). Head CT and HIV were negative. MRI of the face and orbits showed increased T2 signal of the optic nerves bilaterally, left greater than right. Based on the imaging and lab results, he was diagnosed with tertiary syphilis and received 3 doses of 2.4M U of penicillin G benzathine intramuscularly (IM).A few months later, the patient was admitted for progression of central vision impairment that was worse in the left eye despite prior treatment. RPR titer was 1:16. CSF did not show pleocytosis or increased protein and VDRL was non-reactive. He was treated with a 2-week course of IV penicillin G q4h for incompletely treated ocular syphilis. At a recent ophthalmology appointment, he noted mild improvement in his vision. Repeat RPR titer was 1:8.
Discussion: Ocular syphilis occurs in roughly 0.5-1.5% of patients with syphilis of any stage, most commonly at the primary or secondary stage. Ocular involvement can affect any eye structure with posterior and pan-uveitis being the most common manifestations. Even with a negative CSF exam, patients should be treated with the same regimen as patients with neurosyphilis. If patients are presenting with ocular findings only, and no cranial nerve dysfunction or other neurological deficits, CSF exam is not needed prior to initiating treatment (1). In immunocompetent individuals and HIV patients compliant with ART, repeat CSF exam is not needed as following the normalization of serum RPR is sufficient. All patients should be screened for HIV at the time of ocular syphilis diagnosis as co-infection is common (2). Our patient previously received three doses of penicillin IM which is typically indicated for late latent or tertiary syphilis without neurologic signs and syphilis of unknown duration. He likely should have received two weeks of IV penicillin when initially found to have a positive serology and ocular findings on imaging. The outcome of initial under treatment, as in this case, has rarely been studied. One retrospective study from Malaysia found that patients with ocular syphilis had recurrent disease rates of 11% (1/9) after IV penicillin regimen vs. 100% (1/1) with IM penicillin regimen (3).
Conclusions: Cases of syphilis are on the rise. Clinicians should be aware that ocular syphilis can occur at any stage of infection and that any neurologic and/or ocular findings with a history of positive serology tests should prompt further evaluation and immediate treatment. Delayed treatment has been linked to poorer outcomes in visual acuity. Furthermore, CSF VDRL is not highly sensitive and repeat CSF studies are not necessary as RPR normalization is often sufficient as a marker of treatment.