A 28-year-old man with active trachoma (TF stage) undergoes conjunctival examination. His ophthalmologist wants to grade the severity and assess for cicatricial changes. Which investigation is most appropriate to detect early cicatricial trachoma (TS stage)?

## Grading and Assessment of Trachoma Severity **Key Point:** Slit-lamp biomicroscopy is the gold standard for detecting and grading cicatricial changes in trachoma. It allows direct visualization of tarsal conjunctival scarring, which defines the TS (Trachomatous Scarring) stage. ### WHO Simplified Grading System for Trachoma | Stage | Clinical Finding | Investigation | | --- | --- | --- | | **TF** (Trachomatous Inflammation-Follicular) | ≥5 follicles on upper tarsal conjunctiva | Clinical examination | | **TI** (Trachomatous Inflammation-Intense) | Intense inflammation obscuring vessels | Clinical examination | | **TS** (Trachomatous Scarring) | Conjunctival scarring on upper tarsus | **Slit-lamp biomicroscopy** | | **TT** (Trachomatous Trichiasis) | ≥1 trichiatic lash rubbing cornea | Slit-lamp examination | | **CO** (Corneal Opacity) | Opacity obscuring pupil | Slit-lamp examination | ### Why Slit-Lamp Biomicroscopy? **High-Yield:** Slit-lamp provides: 1. **Magnification** (10–40×) to visualize fine scarring patterns 2. **Directed illumination** to highlight conjunctival surface irregularities 3. **Anterior segment imaging** to assess corneal involvement (pannus, opacity) 4. **Documentation** of scarring severity for follow-up and epidemiological surveys ### Cicatricial Changes in TS Stage **Clinical Pearl:** Early cicatricial trachoma (TS) manifests as: - **Arlt's line** — horizontal linear scar on upper tarsal conjunctiva (pathognomonic) - **Conjunctival blanching** and loss of normal vascular pattern - **Trichiasis** (inturned lashes) may develop - **Entropion** and **corneal scarring** in advanced stages Slit-lamp biomicroscopy is essential to detect these subtle changes before they progress to sight-threatening complications. ### Why Other Options Are Incorrect **Warning:** Giemsa staining detects active infection (inclusions) but cannot assess structural scarring. Biopsy is invasive and unnecessary. Fluorescein angiography is not indicated for conjunctival trachoma assessment. **Mnemonic:** **SLIT** — Slit-lamp Is the Investigation of choice for Trachomatous scarring (TS stage).