A 58-year-old woman presents with acute onset severe eye pain, blurred vision, and nausea. Examination reveals a mid-dilated pupil, corneal edema, shallow anterior chamber, and intraocular pressure of 58 mmHg. Gonioscopy shows an appositionally closed angle. All of the following are characteristic features of acute angle-closure glaucoma EXCEPT:

Explanation

## Acute Angle-Closure Glaucoma: Distinguishing True from False Features ### Mechanism of Angle Closure **Key Point:** In acute angle-closure glaucoma, the peripheral iris is pushed forward against the trabecular meshwork, obstructing aqueous outflow. This occurs because the lens is positioned anteriorly (due to its size, zonular laxity, or ciliary body swelling), not because the anterior chamber deepens. ### Analysis of Each Option | Feature | Status | Explanation | |---------|--------|-------------| | Dark room test & pharmacologic dilation precipitate attack | **Correct** | Mydriasis causes iris to bunch up peripherally, worsening angle closure | | Fellow eye prophylaxis with laser PI | **Correct** | ~50% of fellow eyes develop angle closure; PI is standard preventive care | | **Anterior chamber depth INCREASED** | **INCORRECT** | AC depth is **shallow/decreased**, not increased; this is a key anatomical finding | | Iris-trabecular meshwork apposition blocks drainage | **Correct** | This is the fundamental pathophysiology | ### Anatomical Basis **High-Yield:** The predisposing anatomy in angle-closure glaucoma includes: - **Shallow anterior chamber** (reduced depth) - Short axial length (hyperopia) - Thick lens - Anterior lens position - Narrow angle (< 20°) The attack is triggered when the lens moves **forward**, further reducing AC depth and pushing the iris against the angle structures. ### Clinical Pearl The anterior chamber becomes **shallower** during an acute attack due to corneal edema, lens swelling, and ciliary body congestion—not deeper. Increased AC depth would actually **reduce** angle-closure risk. **Warning:** Confusing shallow vs. deep anterior chamber is a common trap. Remember: angle-closure occurs in **anatomically crowded eyes** with naturally shallow chambers.