A 58-year-old man presents with sudden onset of pain and redness in the left eye for 2 days. He reports blurred vision and halos around lights. On examination, visual acuity is 6/60 in the left eye. The cornea shows mild edema, the anterior chamber is shallow, and the iris appears bombé. Intraocular pressure (IOP) is 48 mmHg in the left eye and 16 mmHg in the right eye. Gonioscopy reveals a closed angle with iris-lens diaphragm pushed forward. B-scan ultrasonography shows a normal posterior segment with no retinal detachment. What is the most likely diagnosis?

Explanation

## Clinical Presentation Analysis **Key Point:** The combination of shallow anterior chamber, bombé iris, and closed angle on gonioscopy in the setting of acute IOP elevation indicates pupillary block mechanism. ### Pathophysiology of Pupillary Block Pupillary block occurs when the iris is pushed forward by relative apposition of the lens to the iris, obstructing aqueous flow from the posterior chamber to the anterior chamber. This creates a pressure gradient that: 1. Pushes the iris periphery forward 2. Closes the drainage angle 3. Prevents aqueous egress through the trabecular meshwork 4. Causes acute IOP elevation ### Distinguishing Features in This Case | Feature | Pupillary Block | Phacomorphic | Uveitic | Lens-Particle | |---------|-----------------|--------------|---------|---------------| | **Iris position** | Bombé (forward) | Normal | Normal or posterior | Normal | | **Angle appearance** | Closed | Open | Open | Open | | **Corneal clarity** | Edematous | Clear | Variable | Clear | | **Anterior chamber** | Shallow | Deep | Variable | Deep | | **Lens status** | Normal | Intumescent | Normal | Cataractous | | **Posterior segment** | Normal | Normal | Inflammation | Normal | **High-Yield:** The bombé iris (forward bulging) is pathognomonic for pupillary block and distinguishes it from other secondary glaucomas where the angle remains open. ### Clinical Pearl The shallow anterior chamber with closed angle on gonioscopy is the gold standard finding for pupillary block. B-scan ruling out retinal detachment excludes aqueous misdirection from posterior segment pathology. **Warning:** Do not confuse pupillary block glaucoma (which can be primary or secondary) with phacomorphic glaucoma—the latter occurs when a mature/hypermature lens swells and physically pushes the iris-lens diaphragm forward, but the angle remains open initially.