Initial Workup for Uveitis
The initial workup for uveitis should be guided by the anatomic location and clinical features of the inflammation, with syphilis serology being the only universal test recommended for all cases 1.
Algorithmic Approach to Initial Workup
Step 1: Clinical Classification (No Laboratory Tests Yet)
Before ordering any tests, classify the uveitis by:
- Anatomic location: anterior, intermediate, posterior, or panuveitis
- Laterality: unilateral vs bilateral
- Course: acute, chronic, or recurrent
- Granulomatous features: presence of keratic precipitates, iris nodules, or choroidal granulomas
- Severity markers: visual acuity, vitreous haze grade, macular involvement, retinal vasculitis
Step 2: Universal Screening
Syphilis serology is the ONLY test appropriate for all forms of uveitis 1. This is critical because syphilis can mimic virtually any uveitis presentation and is treatable.
Step 3: Anatomically-Guided Testing
After syphilis screening, further workup depends on the anatomic pattern:
For Unilateral Acute Anterior Non-Granulomatous Uveitis:
For Chronic Uveitis (Any Location):
- Serum angiotensin-converting enzyme (ACE) 1
- Interferon-gamma release assay (IGRA) for tuberculosis 1
- Chest CT (not just radiography) 1
- These target sarcoidosis and tuberculosis, the most important chronic causes
For Intermediate or Posterior Uveitis in Patients >40 Years:
- Cerebral MRI 1
- Anterior chamber tap with IL-10 analysis 1
- This combination screens for intraocular lymphoma, which is a masquerade syndrome with devastating consequences if missed
For Severe, Bilateral, Recurrent, or Chronic Anterior Uveitis:
Step 4: Baseline Assessment Before Immunosuppression
If systemic immunomodulatory therapy is being considered, additional screening is required 3:
- Baseline vital organ function: complete blood count, comprehensive metabolic panel, liver function tests
- Infectious disease screening: tuberculosis testing (IGRA or PPD), HIV serology, hepatitis B and C serology
- Malignancy risk assessment: age, prior immunosuppression exposure, family history
Critical Pitfalls to Avoid
Do not order non-directed testing - The diagnostic yield of investigations ordered without clinical orientation is extremely low 1. The prospective ULISSE study demonstrated that a standardized, anatomically-guided approach achieved comparable diagnostic yield to unrestricted testing while substantially reducing costs 4, 1.
Watch for granulomatous features and synechiae - These findings significantly increase the likelihood of finding a specific etiology on workup and should prompt more thorough investigation, particularly for sarcoidosis, tuberculosis, and in older patients, intraocular lymphoma 5.
Consider masquerade syndromes - Before escalating immunosuppression, always reconsider infection and malignancy (especially intraocular lymphoma in patients >40 with intermediate/posterior uveitis) 3.
When Additional Testing is Warranted
A second-line workup may be indicated if 5:
- Initial workup is negative (idiopathic uveitis) AND clinical features evolve
- New synechiae develop
- Granulomatous features appear
- Follow-up extends beyond 40 months without diagnosis
- Focus on sarcoidosis, intraocular lymphoma, and inflammatory bowel disease in these scenarios
Imaging Considerations
Optical coherence tomography (OCT) and fundus fluorescein angiography (FFA) are essential for posterior segment involvement to assess macular edema (central macular thickness ≥240 μm correlates with worse vision), retinal vasculitis, and structural complications 3, 6. Ultra-widefield imaging is particularly valuable in Behçet disease and other vasculitic uveitis 6.