In primary angle-closure glaucoma, which anatomical configuration is MOST predisposing?

Explanation

## Anatomical Risk Factors in Primary Angle-Closure Glaucoma **Key Point:** The "crowded anterior segment" is the hallmark predisposing anatomy. Short eyes (hyperopia) with shallow chambers and thick lenses are at highest risk for angle closure. ### Anatomical Features Associated with Angle Closure | Feature | Why It Predisposes | |---------|-------------------| | **Short axial length (hyperopia)** | Crowded anterior segment; lens closer to cornea | | **Shallow anterior chamber** | Reduced space; iris-lens proximity increases | | **Thick lens** | Greater posterior pressure on iris | | **Narrow angle (< 20°)** | Less trabecular meshwork exposed; easier to close | | **Anterior lens position** | Increases pupillary block risk | | **Plateau iris** | Ciliary body positioned anteriorly; angle closure without pupillary block | | **Posterior iris insertion** | Iris-trabecular contact more likely | ### Why Hyperopia Is a Risk Factor 1. Shorter eye → compressed anterior segment 2. Lens relatively larger in proportion to eye size 3. Anterior chamber depth reduced 4. Angle width narrowed 5. Pupillary block more likely to occur **High-Yield:** A hyperopic eye with shallow anterior chamber is the **classic predisposing anatomy**. This is why gonioscopy and anterior chamber depth measurement (A-scan, OCT) are essential screening tools in hyperopic patients. **Mnemonic:** **SHALLOW** — Short axial length, Hyperopia, Anterior chamber depth (reduced), Lens (thick/anterior), Lens-iris proximity, Obtuse angle (narrow), White race (relative risk), Younger age (relative to open-angle glaucoma) **Clinical Pearl:** Angle-closure glaucoma is more common in East Asian and Inuit populations and in women (due to shorter axial length). It typically presents in the 5th–6th decade.