A 32-year-old man presents with acute onset photophobia, pain, and blurred vision. Slit-lamp examination reveals anterior chamber inflammation with keratic precipitates and posterior synechiae. What is the most common cause of anterior uveitis in India?

Explanation

## Most Common Cause of Anterior Uveitis in India **Key Point:** Tuberculosis is the most common identifiable cause of anterior uveitis in India, accounting for approximately 20–30% of cases in endemic regions. It typically presents as a granulomatous anterior uveitis with mutton-fat keratic precipitates and posterior synechiae. ### Clinical Features of Tuberculous Uveitis - **Anterior presentation:** Granulomatous inflammation with large keratic precipitates - **Posterior involvement:** Choroidal tubercles, epiretinal membrane, vasculitis - **Associated findings:** Iris nodules, Busacca nodules on ciliary body - **Systemic correlation:** May be associated with pulmonary TB or miliary TB ### Epidemiological Context | Cause | Frequency in India | Global Frequency | Key Feature | | --- | --- | --- | --- | | **Tuberculosis** | 20–30% | 5–10% | Granulomatous, choroidal tubercles | | Syphilis | 5–10% | 2–5% | Anterior + posterior, Argyll Robertson pupil | | Toxoplasmosis | 10–15% (posterior) | 30–50% (posterior) | Focal retinochoroiditis, "headlight in headlight" | | Sarcoidosis | 3–5% | 10–15% | Granulomatous, systemic involvement | | Idiopathic | 40–50% | 40–50% | No identifiable cause | **High-Yield:** In an Indian patient with granulomatous anterior uveitis, always screen for TB with chest X-ray, TB-IGRA (or Mantoux test), and sputum examination before attributing the uveitis to idiopathic or autoimmune causes. ### Diagnostic Approach 1. **Mantoux test** or TB-IGRA (QuantiFERON-TB Gold) 2. **Chest X-ray** — look for hilar lymphadenopathy, apical infiltrates, or miliary pattern 3. **Sputum smear microscopy** and culture if symptomatic 4. **Anterior chamber tap** (if diagnosis unclear) — PCR for *Mycobacterium tuberculosis* 5. **Fundus examination** — search for choroidal tubercles (pathognomonic but rare) **Clinical Pearl:** Choroidal tubercles are seen in only 1–5% of ocular TB cases but are highly specific; their presence confirms TB as the cause of uveitis. **Warning:** Do not dismiss TB uveitis as idiopathic. Even latent TB (positive Mantoux, negative CXR) can reactivate and cause uveitis, especially if the patient is immunocompromised or on anti-TNF therapy.