What is the diagnostic approach for uveitis?

Diagnostic Approach for Uveitis

Uveitis is diagnosed through a comprehensive ophthalmologic examination combined with targeted laboratory and imaging studies based on clinical presentation, with slit-lamp examination being the cornerstone for detecting inflammatory cells in the eye. 1

Clinical Examination Components

Ophthalmologic Examination

• Slit-lamp examination: Essential for visualizing inflammatory cells in the anterior chamber and grading inflammation according to Standardization of Uveitis Nomenclature (SUN) criteria 1

  • Grade 1+ anterior chamber cells = 6-15 cells per field in a 1-mm × 1-mm slit beam 1
  • Assessment of flare (protein leakage)
  • Detection of keratic precipitates
  • Evaluation for synechiae (adhesions)

• Fundoscopic examination: To assess vitreous cells, retinal lesions, and optic nerve involvement

• Visual acuity testing: To establish baseline and monitor disease progression

• Intraocular pressure measurement: To detect complications like glaucoma or hypotony

Anatomical Classification

Uveitis is classified anatomically to guide diagnosis and treatment 1, 2:

• Anterior uveitis (iris, ciliary body)
• Intermediate uveitis (vitreous)
• Posterior uveitis (retina, choroid)
• Panuveitis (all segments)

Laboratory Testing Strategy

First-Line Tests (For All Uveitis Patients)

• Syphilis serology (VDRL/RPR and treponemal test): Recommended for all forms of uveitis 3
• Complete blood count: To assess for systemic inflammation 4
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP): Non-specific inflammatory markers 4
• Tuberculin skin test or interferon-gamma release assay (Quantiferon): High diagnostic yield (17-24%) 4, 3
• Chest X-ray: To screen for sarcoidosis and tuberculosis (8.4% yield) 4

Second-Line Tests (Based on Clinical Presentation)

For Anterior Uveitis

• HLA-B27 testing: Particularly for unilateral acute non-granulomatous anterior uveitis (56.3% yield) 4, 3
• Sacroiliac imaging: If spondyloarthritis is suspected (46.4% yield) 4

For Intermediate/Posterior/Panuveitis

• Chest CT scan: For suspected sarcoidosis (30.3% yield) 4
• Angiotensin-converting enzyme (ACE): For suspected sarcoidosis (16.5% yield) 4
• Brain MRI: For intermediate or posterior uveitis in patients >40 years 3
• Anterior chamber tap with IL-10 analysis: For suspected intraocular lymphoma 3
• Serum calcium and liver function tests: For sarcoidosis evaluation (low yield: 2-3%) 4

For Suspected Infectious Causes

• PCR testing of ocular fluids: For viral (HSV, VZV, CMV) or bacterial pathogens 1
• Toxoplasma serology: For characteristic retinal lesions 1

Special Considerations

Juvenile Idiopathic Arthritis (JIA)-Associated Uveitis

• Regular ophthalmologic screening is mandatory for all JIA patients 1
• Risk factors: early-onset arthritis, ANA positivity, oligoarticular subtype 1
• Screening frequency: every 3 months for high-risk patients 1

Inflammatory Bowel Disease (IBD)-Associated Uveitis

• Differentiate episcleritis (often parallels bowel disease activity) from uveitis (can be independent of bowel symptoms) 1
• Urgent ophthalmology referral for visual disturbance, photophobia, or moderate-severe eye pain 1

Sarcoidosis-Associated Uveitis

• Ophthalmologic examination recommended for all sarcoidosis patients, even without ocular symptoms 1
• Prevalence of ocular involvement: 20-40% of sarcoidosis patients 1

Common Pitfalls to Avoid

1. Delayed diagnosis: Uveitis can cause permanent visual loss if not promptly diagnosed and treated 1

2. Over-reliance on immunological tests: Many immunological tests have low diagnostic yield and should not be ordered routinely 4, 3

3. Missing infectious causes: Failure to rule out infectious etiologies before starting immunosuppressive therapy can worsen outcomes 1

4. Inadequate follow-up: Patients on topical glucocorticoids require monitoring within 1 month after each change in therapy 1

5. Overlooking asymptomatic uveitis: Some patients, especially children with JIA, may have asymptomatic uveitis requiring screening 1

By following this structured diagnostic approach, clinicians can efficiently diagnose uveitis, determine its etiology, and initiate appropriate treatment to prevent vision loss.