Clinical Presentation of Bilateral Optic Nerve Edema

Evaluating patients who present with bilateral optic nerve edema requires a systematic clinical approach, as this finding can stem from intracranial hypertension, systemic inflammation, or active infection. A recent clinical case highlights a 58-year-old woman presenting with progressive, painless bilateral blurred vision over several days, affecting her right eye more severely than her left. Two months prior to her presentation, she developed a diffuse, pruritic cutaneous rash that notably spared her face. Comprehensive ophthalmic evaluation revealed significantly reduced visual acuity bilaterally, optic nerve edema, anterior uveitis, and scattered intraretinal and peripapillary nerve fiber layer hemorrhages. Additionally, magnetic resonance imaging demonstrated bilateral optic nerve head enhancement.

Clinicians encountering bilateral optic nerve edema accompanied by intraocular inflammation must rapidly differentiate between non-infectious autoimmune uveitis and infectious etiologies. In this patient, the history of a preceding generalized dermatologic eruption provided a crucial clinical clue pointing toward a systemic infectious process. Diagnostic evaluation focused on obtaining detailed blood serologies and neuroimaging to characterize optic nerve involvement. Identifying optic nerve swelling alongside active anterior uveitis narrowed the differential diagnosis significantly, prompting comprehensive infectious serological testing for spirochetal and granulomatous pathogens.

Diagnostic Workup and Serum Serology Interpretation

The laboratory evaluation in this clinical scenario yielded initially complex serological results that required careful interpretation. Serum antibody testing returned positive for Borrelia burgdorferi; however, the confirmatory Lyme disease Western blot was negative. Simultaneously, serum treponemal antibody testing was strongly positive, accompanied by a markedly elevated rapid plasma reagin titer of 1:1,024. This specific serological pattern illustrates a critical diagnostic pitfall in neuro-ophthalmology where spirochetal cross-reactivity can create diagnostic confusion.

Spirochetes such as Borrelia burgdorferi and Treponema pallidum express overlapping outer membrane antigens. Consequently, automated enzyme-linked immunosorbent screening assays for Lyme disease frequently exhibit false-positive reactivity in patients harboring active Treponema pallidum infections. Clinicians must recognize that a positive Lyme screening assay in the setting of a negative Western blot does not confirm Lyme disease. Instead, the markedly elevated non-treponemal rapid plasma reagin titer, paired with reactive treponemal antibodies, unequivocally confirmed active syphilis. Furthermore, the patient’s antecedent pruritic rash aligned with secondary syphilis, which frequently precedes neuro-ophthalmic involvement.

Evaluating Cerebrospinal Fluid in Ocular Syphilis

Following serological confirmation of systemic syphilis, evaluating central nervous system involvement became an essential next step. The patient underwent a diagnostic lumbar puncture to assess for neurosyphilis. Cerebrospinal fluid analysis demonstrated normal total protein levels and a mild elevation in nucleated cells with a lymphocytic predominance. Surprisingly, the cerebrospinal fluid Venereal Disease Research Laboratory test returned negative. This finding frequently creates diagnostic uncertainty among clinicians evaluating suspected neuro-ophthalmic syphilis.

Importantly, a negative cerebrospinal fluid Venereal Disease Research Laboratory test does not rule out neurosyphilis or ocular syphilis. Although the test is highly specific, its sensitivity remains relatively low, ranging between thirty and seventy percent across various studies. Therefore, clinicians should never withhold intravenous penicillin therapy based solely on a negative Venereal Disease Research Laboratory result when serum treponemal serology is reactive and ocular signs are present. Major medical guidelines emphasize that ocular syphilis must be treated with a full course of intravenous penicillin under neurosyphilis management protocols regardless of lumbar puncture outcomes.

Differential Diagnosis of Inflammatory Optic Neuropathy

Constructing a comprehensive differential diagnosis for bilateral optic nerve edema combined with intraocular inflammation requires systematic evaluation. Infectious candidates include Treponema pallidum, Borrelia burgdorferi, Mycobacterium tuberculosis, Bartonella henselae, Toxoplasma gondii, and various herpesviruses. Each of these pathogens can induce optic disc swelling, papillitis, and variable anterior or posterior uveitis. However, systemic features, targeted laboratory panels, and exposure histories help clinicians isolate the true underlying cause.

Non-infectious autoimmune and systemic inflammatory conditions also feature prominently in this differential diagnosis. Sarcoidosis, Behçet disease, Vogt-Koyanagi-Harada syndrome, and myelin oligodendrocyte glycoprotein antibody-associated disease can present with optic disc swelling and uveitis. In addition, elevated intracranial pressure from idiopathic intracranial hypertension typically causes bilateral papilledema without intraocular inflammation or anterior chamber cellular activity. Therefore, discovering anterior uveitis alongside retinal hemorrhages strongly points toward active infectious panuveitis or immune-mediated intraocular inflammation rather than simple mechanical papilledema.

Therapeutic Management and Clinical Reasoning Pitfalls

Once ocular syphilis is identified, prompt initiation of parenteral antimicrobial therapy is essential to prevent permanent visual loss and neurological complications. The standard therapeutic regimen consists of intravenous aqueous crystalline penicillin G administered at 18 to 24 million units daily for ten to fourteen days. For patients with documented penicillin hypersensitivity, desensitization remains the preferred approach; however, intravenous ceftriaxone serves as an effective alternative under close supervision.

Clinicians must maintain vigilance for potential treatment complications, such as the Jarisch-Herxheimer reaction. This transient systemic inflammatory reaction occurs shortly after starting antibiotics due to rapid spirochete lysis. Additionally, clinicians must avoid common reasoning pitfalls, such as relying excessively on a negative cerebrospinal fluid Venereal Disease Research Laboratory test or misinterpreting a false-positive Lyme screen. Adjunctive corticosteroids may be considered in severe ocular inflammation once effective intravenous antimicrobial therapy is established. Serial clinical examinations and non-treponemal titers confirm treatment success.

Key Takeaways for Clinical Practice

This clinical case highlights the crucial importance of maintaining high clinical suspicion for syphilis in any patient presenting with unexplained intraocular inflammation or optic nerve edema. Syphilis is renowned as the great imitator because its clinical manifestations span dermatology, neurology, and ophthalmology. Consequently, routine screening with non-treponemal and treponemal assays is essential whenever clinicians evaluate optic neuritis or panuveitis of unknown etiology.

Furthermore, sound clinical reasoning skills are essential when interpreting discordant laboratory results. Recognizing spirochetal antigen cross-reactivity prevents diagnostic delays and ensures timely administration of targeted antibiotic therapy. Clinicians must remember that ocular syphilis carries the same clinical urgency as neurosyphilis. By following evidence-based diagnostic algorithms and adhering to recommended intravenous penicillin regimens, healthcare providers can preserve visual acuity and prevent long-term neurological sequelae in affected patients.

Frequently Asked Questions

Can ocular syphilis occur with a negative CSF VDRL result?

Yes. While the CSF VDRL test is highly specific for neurosyphilis, its sensitivity is relatively low, ranging from 30% to 70%. Consequently, a negative CSF VDRL result does not exclude neurosyphilis or ocular syphilis. Clinicians should treat patients with reactive serum treponemal serology and compatible ocular symptoms using intravenous penicillin regimens.

Why do Lyme disease screening tests show false positives in syphilis?

False-positive Lyme disease screening tests occur because Borrelia burgdorferi and Treponema pallidum share cross-reactive spirochetal surface antigens. As a result, automated enzyme immunoassays for Lyme disease can show reactivity in patients with active syphilis. Confirmation requires a negative Lyme Western blot alongside positive treponemal and non-treponemal serological testing.

What is the recommended treatment regimen for ocular syphilis?

Current clinical guidelines recommend treating ocular syphilis using standard neurosyphilis protocols, regardless of lumbar puncture results. The primary regimen is intravenous aqueous crystalline penicillin G at 18 to 24 million units daily for 10 to 14 days. Alternative options, such as intravenous ceftriaxone, require careful evaluation in penicillin-allergic patients.

Disclaimer: This content is for informational and educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider with any questions regarding a medical condition. Refer to the latest local and national guidelines for clinical practice.

References

1. Diaz Curbelo C et al. Clinical Reasoning: A 58-Year-Old Woman With Painless Blurry Vision. Neurology. 2026 Jul 14. doi: 10.1212/WNL.0000000000218244. PMID: 42314100.


2. Centers for Disease Control and Prevention. Sexually Transmitted Infections Treatment Guidelines: Syphilis and Ocular Syphilis Management. MMWR Recomm Rep. 2021;70(4):1-187.


3. Oliver SE, Aubin W, Suparna M, et al. Neurosyphilis, Ocular Syphilis, and Otosyphilis: Diagnostic and Therapeutic Challenges. Clin Infect Dis. 2020;71(Suppl 1):S12-S20.