Which of the following is the primary mechanism of glaucoma in phacomorphic glaucoma?

Explanation

## Phacomorphic Glaucoma: Mechanism **Key Point:** Phacomorphic glaucoma is a **secondary angle-closure glaucoma** caused by a swollen (intumescent) cataractous lens that mechanically pushes the iris forward, leading to pupillary block and angle closure. ### Pathophysiology The term "phacomorphic" literally means "lens-shaped/form" — the glaucoma arises due to the **physical size and shape** of the swollen lens: 1. **Lens swelling** — cortical hydration in a maturing cataract causes the lens to become intumescent (swollen), increasing its anteroposterior diameter. 2. **Pupillary block** — the enlarged lens presses against the posterior iris surface, impeding aqueous flow from the posterior to the anterior chamber. 3. **Iris bombé and angle closure** — increased posterior chamber pressure bows the peripheral iris forward (iris bombé), mechanically closing the iridocorneal angle and obstructing the trabecular meshwork. 4. **Acute IOP elevation** — aqueous outflow is blocked, causing a rapid, often dramatic rise in IOP. ### Clinical Features - **Presentation:** Acute painful red eye with markedly elevated IOP in the setting of a dense/mature cataract; typically unilateral. - **Angle appearance on gonioscopy:** **Closed** (distinguishing it from phacolytic glaucoma). - **Anterior chamber:** Shallow, with a convex iris configuration. - **Fellow eye:** May show a narrow angle due to anatomical predisposition. - **Resolution:** Urgent cataract extraction is the definitive treatment; laser iridotomy may temporize by relieving pupillary block. ### Distinction from Similar Conditions | Feature | Phacomorphic | Phacolytic (Phacogenic) | Phacoanaphylactic | |---------|--------------|------------------------|-------------------| | **Mechanism** | Mechanical angle closure by swollen lens | Lens protein leakage through intact capsule → trabecular obstruction | Immune reaction to lens antigens | | **Angle status** | **Closed** | Open | Open | | **Cataract type** | Intumescent/mature | Hypermature (Morgagnian) | Post-traumatic/surgical capsule rupture | | **Inflammation** | Minimal | Mild (white particles in AC) | Marked granulomatous | **High-Yield:** Phacomorphic glaucoma = **angle-closure** due to a **swollen lens** mechanically displacing the iris. This is distinct from **phacolytic glaucoma**, which is an open-angle glaucoma caused by lens protein leakage through an intact capsule in a hypermature cataract (Kanski's Clinical Ophthalmology; Parsons' Diseases of the Eye). **Clinical Pearl:** Option A describes the mechanism of **phacolytic glaucoma** (not phacomorphic). The key distinguishing feature is gonioscopy: phacomorphic = closed angle; phacolytic = open angle.