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Ocular syphilis — Clinical Guidelines

Overview

Ocular syphilis is an infectious uveitis caused by Treponema pallidum, the bacterium responsible for syphilis. It can affect any part of the eye, including the cornea, anterior and posterior uvea, retina, and choroid, leading to significant visual impairment if left untreated. The condition predominantly affects adults, particularly those with untreated or inadequately treated systemic syphilis. Early diagnosis and prompt treatment are crucial to prevent irreversible ocular damage and preserve vision. In day-to-day practice, recognizing the signs and symptoms of ocular syphilis and promptly initiating appropriate therapy can significantly mitigate the risk of blindness 1.

Pathophysiology

Ocular syphilis results from hematogenous spread of Treponema pallidum to ocular tissues following systemic infection. Once in the eye, the spirochetes trigger an intense inflammatory response mediated by both innate and adaptive immune systems. This immune reaction leads to various ocular manifestations depending on the affected structures. In the posterior segment, syphilitic inflammation can cause chorioretinal scars, choroidal neovascularization, and optic neuropathy. The anterior segment involvement may manifest as interstitial keratitis, anterior uveitis, or scleritis. Molecularly, the presence of treponemal antigens stimulates the production of pro-inflammatory cytokines such as TNF-α, IL-6, and IL-1β, contributing to tissue damage and visual impairment 1.

Epidemiology

The incidence of ocular syphilis has fluctuated over time, often correlating with trends in systemic syphilis rates. It is more prevalent in sexually active adults, with a slight male predominance. Geographic regions with higher rates of untreated sexually transmitted infections tend to report more cases. Specific incidence and prevalence figures are not consistently reported across studies, but trends indicate an increase in cases linked to broader public health issues related to sexually transmitted infections and access to healthcare. Risk factors include immunocompromised states, untreated or inadequately treated syphilis, and delayed diagnosis and treatment of systemic syphilis 1.

Clinical Presentation

Patients with ocular syphilis can present with a wide range of symptoms, from asymptomatic to severe visual disturbances. Typical presentations include blurred vision, floaters, photophobia, and ocular pain. Anterior segment involvement may present with redness, tearing, and anterior chamber inflammation. Posterior segment manifestations can include retinal vasculitis, chorioretinal scars, and optic disc swelling. Red-flag features include sudden vision loss, significant visual field defects, and signs of optic neuropathy, which necessitate urgent evaluation and intervention 1.

Diagnosis

The diagnostic approach to ocular syphilis involves a combination of clinical evaluation, serological testing, and imaging modalities. Key steps include:

Clinical Examination: Detailed ocular examination to identify specific signs of syphilitic involvement.

Serological Testing:

- Non-treponemal Tests: Venereal Disease Research Laboratory (VDRL) or Rapid Plasma Reagin (RPR) tests to assess for active infection. Titers ≥ 1:8 are often considered significant 1. - Treponemal Tests: Fluorescent Treponemal Antibody Absorption (FTA-ABS) or enzyme-linked immunosorbent assay (ELISA) to confirm syphilis infection. Positive results require clinical correlation.

Imaging:

- Indocyanine Green Angiography (ICGA): Reveals characteristic hypofluorescent dots and choroidal hypofluorescence patterns indicative of syphilitic uveitis 1. - Optical Coherence Tomography (OCT): Useful for assessing retinal and choroidal thickness changes and inflammation 1.

Differential Diagnosis:

- Other Uveitides: Behçet's disease, sarcoidosis, and Vogt-Koyanagi-Harada syndrome can mimic ocular syphilis but are distinguished by specific clinical and serological features. - Infectious Causes: Endogenous endophthalmitis, toxoplasmosis, and other retinitis conditions require differential consideration based on clinical context and imaging findings 1 2.

Management

First-Line Treatment

Antibiotic Therapy: Penicillin G is the first-line treatment.

- Adults: Intramuscular penicillin G benzathine 2.4 million units in a single dose or procaine penicillin G 1.8-2.4 million units daily for 14-21 days 1. - Penicillin-Allergic Patients: Doxycycline 100 mg orally twice daily for 14-21 days or ceftriaxone 2 g intravenously every 12 hours for 14 days 1.

Monitoring: Regular follow-up with serological testing to ensure declining titers and clinical improvement 1.

Second-Line Treatment

Refractory Cases: For patients who do not respond to initial therapy or have severe disease:

- Adjunctive Therapy: Corticosteroids (e.g., prednisone 40-60 mg daily for 4-6 weeks) may be considered to manage inflammation, especially in posterior segment involvement 1. - Immunomodulatory Agents: In cases of refractory uveitis, agents like methotrexate or mycophenolate mofetil might be necessary under specialist supervision 1.

Specialist Escalation

Optic Neuropathy or Severe Visual Loss: Referral to a neuro-ophthalmologist for specialized management.

Choroidal Neovascularization: Consider intravitreal anti-VEGF therapy or photodynamic therapy as adjuncts, guided by retinal specialist recommendations 7.

Complications

Acute Complications: Rapid vision loss, retinal detachment, and neovascular glaucoma can occur if inflammation is severe or untreated.

Long-Term Complications: Chorioretinal scars, optic atrophy, and permanent visual impairment are common sequelae if treatment is delayed or inadequate.

Management Triggers: Prompt recognition and aggressive treatment of active inflammation, regular monitoring for signs of complications, and timely referral to specialists when necessary 1.

Prognosis & Follow-Up

The prognosis for ocular syphilis varies based on the extent of ocular involvement and the timeliness of treatment. Early intervention generally leads to better outcomes with reduced risk of permanent visual loss. Prognostic indicators include the severity of initial ocular damage and the presence of optic nerve involvement. Recommended follow-up intervals typically include:

Initial Follow-Up: Within 1-2 weeks post-treatment initiation to assess response.

Subsequent Monitoring: Every 1-3 months for the first year, then annually if stable 1.

Special Populations

Pregnancy: Treatment strategies must balance maternal and fetal safety; penicillin remains the preferred antibiotic, with careful monitoring of both mother and infant 1.

Elderly Patients: Increased vigilance for complications and potential drug interactions; dose adjustments may be necessary 1.

Immunocompromised Individuals: Higher risk of severe disease and complications; close monitoring and possibly more aggressive treatment regimens are advised 1.

Key Recommendations

Initiate Prompt Serological Testing for syphilis in patients with suspected ocular syphilis, including non-treponemal and treponemal tests (Evidence: Strong 1).

Use ICGA and OCT for detailed evaluation of posterior segment involvement (Evidence: Moderate 1).

Treat with Penicillin G as first-line therapy for adults (2.4 million units IM in a single dose or procaine penicillin G 1.8-2.4 million units daily for 14-21 days) (Evidence: Strong 1).

Consider Corticosteroids for severe anterior or posterior uveitis (Evidence: Moderate 1).

Refer to Neuro-ophthalmologist for cases involving optic neuropathy or severe visual loss (Evidence: Expert opinion).

Regular Follow-Up with serological testing and clinical evaluation every 1-3 months for the first year post-treatment (Evidence: Moderate 1).

Adjust Treatment for Penicillin Allergies to alternatives like doxycycline or ceftriaxone (Evidence: Strong 1).

Monitor for Complications such as retinal detachment and neovascular glaucoma (Evidence: Moderate 1).

Special Considerations for Pregnancy: Use penicillin cautiously with fetal monitoring (Evidence: Moderate 1).

Tailor Management in Immunocompromised Patients with close monitoring and possibly more aggressive therapy (Evidence: Expert opinion).

References

1 Cenachi SPF, Vinciguerra Neto V, de Oliveira Machado Azevedo D, Ribeiro Campos W, Vasconcelos-Santos DV. Multimodal Imaging Enhanced by Indocyanine Green Angiography in Syphilitic Uveitis. Ocular immunology and inflammation 2026. link 2 Arrieta-Bechara C, Haro-Álvarez B, Cocho-Archiles L, Herreras Cantalapiedra JM. Clinical case: Serpiginous-like choroiditis with macular involvement and good response after treatment with adalimumab. Archivos de la Sociedad Espanola de Oftalmologia 2022. link 3 Moussa K, Alsberge JB, Munk MR, Vora RA, Emami-Naeini P, Yiu G et al.. IDIOPATHIC MULTIFOCAL CHOROIDITIS WITH SERPIGINOUS-LIKE PERIPAPILLARY CHORIORETINAL ATROPHY. Retina (Philadelphia, Pa.) 2022. link 4 Kulkarni RS, Kulkarni P, Shah RJ, Tomar B. Aesthetically Characterized Ocular Prosthesis. Journal of the College of Physicians and Surgeons--Pakistan : JCPSP 2018. link 5 Balci O, Gasc A, Jeannin B, Herbort CP. Enhanced depth imaging is less suited than indocyanine green angiography for close monitoring of primary stromal choroiditis: a pilot report. International ophthalmology 2017. link 6 Liu Z, Li J, Nie S, Guo H, Pan W. Effects of Transcutol P on the corneal permeability of drugs and evaluation of its ocular irritation of rabbit eyes. The Journal of pharmacy and pharmacology 2006. link 7 Navajas EV, Costa RA, Farah ME, Cardillo JA, Bonomo PP. Indocyanine green-mediated photothrombosis combined with intravitreal triamcinolone for the treatment of choroidal neovascularization in serpiginous choroiditis. Eye (London, England) 2003. link

Ocular syphilis