## Herpetic Keratitis — Pathognomonic Findings **Key Point:** The **dendritic ulcer** with characteristic terminal bulbs and rose bengal staining is the pathognomonic hallmark of primary herpetic keratitis [cite:Krachmer Corneal Disease 3e]. ### Dendritic Ulcer Morphology **High-Yield:** The dendritic ulcer is a branching, tree-like epithelial defect with the following features: - **Shape:** Central linear ulcer with lateral branches (resembles a herpes zoster dendrite) - **Terminal bulbs:** Swollen terminal ends of the branches — a key distinguishing feature - **Staining:** Rose bengal or lissamine green stains the ulcer bed and surrounding infected epithelium - **Fluorescein:** Stains the ulcer base; rose bengal stains the entire infected area (more sensitive) ### HSV Keratitis Classification | Stage | Clinical Features | Morphology | | --- | --- | --- | | **Epithelial** | Dendritic ulcer, terminal bulbs | Branching pattern with rose bengal uptake | | **Stromal** | Anterior stromal infiltration, anterior uveitis | Stromal edema, keratic precipitates | | **Endothelial** | Keratic precipitates, anterior chamber reaction | Descemet's folds, corneal edema | **Clinical Pearl:** Rose bengal or lissamine green is superior to fluorescein for visualizing HSV dendritic ulcers because these vital dyes stain infected epithelial cells, not just the ulcer base. Fluorescein may miss early dendrites. **Mnemonic:** **DENT** — **D**endritic, **E**pithelial, **N**on-scarring (initially), **T**erminal bulbs. **Warning:** Repeated herpetic keratitis can progress to stromal disease with scarring and vascularization, but the initial dendritic ulcer is the diagnostic hallmark. 
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