A 62-year-old hyperopic woman from Delhi presents with a 3-day history of recurrent episodes of blurred vision and mild eye discomfort in the right eye, each lasting 30–60 minutes and resolving spontaneously. She denies severe pain or halos. Examination reveals a normal anterior chamber depth, IOP 16 mmHg, and a clear cornea. Gonioscopy shows a narrow angle with appositional closure in the superior quadrant that opens when the patient looks down. What is the most likely diagnosis and the recommended management?

Explanation

## Subacute Angle-Closure Glaucoma: Recognition and Management ### Clinical Spectrum of Angle-Closure ```mermaid flowchart TD A[Narrow-angle eye]:::outcome --> B{Symptoms?}:::decision B -->|None| C[Occludable angle]:::outcome C --> D[Prophylactic iridotomy]:::action B -->|Intermittent blurred vision<br/>mild discomfort| E[Subacute angle-closure]:::outcome E --> F[IOP normal or mildly elevated]:::outcome F --> G[YAG laser iridotomy]:::action B -->|Acute severe pain<br/>halos, corneal edema<br/>IOP >50 mmHg| H[Acute angle-closure]:::urgent H --> I[Medical IOP reduction +<br/>YAG iridotomy]:::action ``` ### Case Analysis: Subacute vs. Acute | Feature | This Case | Acute Angle-Closure | |---------|-----------|---------------------| | Onset | 3 days, recurrent episodes | Sudden, single episode | | Pain severity | Mild discomfort | Severe, unbearable | | Duration | 30–60 min, self-limited | Sustained, progressive | | Halos | Absent | Present | | Corneal clarity | Clear | Edematous | | IOP | Normal (16 mmHg) | Markedly elevated (>50 mmHg) | | Gonioscopy findings | Appositional closure, reversible | Synechial closure, fixed | | Pupil | Normal reactivity | Mid-dilated, fixed | **Key Point:** This patient has **subacute angle-closure**, characterized by intermittent episodes of appositional (reversible) angle closure without acute inflammation or severe IOP elevation. ### Mechanism of Subacute Angle-Closure 1. **Anatomic predisposition:** Hyperopia, short axial length, thick lens, shallow anterior chamber → narrow angle 2. **Intermittent pupillary dilation:** Causes iris bombe and forward lens displacement, narrowing the angle 3. **Appositional closure:** Iris contacts trabecular meshwork but without permanent synechiae formation 4. **Spontaneous resolution:** Pupil constricts, angle reopens, IOP normalizes 5. **Recurrent episodes:** Repeated cycles of closure and opening **Clinical Pearl:** The key distinguishing feature is that gonioscopy shows the angle OPENS when the patient looks down (accommodates and constricts pupil), confirming appositional rather than synechial closure. ### Management of Subacute Angle-Closure **High-Yield:** YAG laser peripheral iridotomy is indicated for subacute angle-closure because: - Eliminates pupillary block, the primary mechanism of angle narrowing - Prevents progression to acute angle-closure attack - Prevents chronic angle-closure with synechial formation and glaucomatous optic neuropathy - Success rate >90% in opening the angle permanently **Procedure:** Bilateral iridotomy (treat fellow eye prophylactically) ### Why NOT the Other Options 1. **Option 0 (Acute angle-closure):** The clinical presentation is NOT acute — no severe pain, no halos, no corneal edema, no markedly elevated IOP. Acute angle-closure is a medical emergency requiring immediate medical therapy before laser. 2. **Option 2 (Physiologic narrow angle with observation):** A physiologic narrow angle is an anatomically narrow angle WITHOUT any symptoms or gonioscopic evidence of closure. This patient has documented appositional closure on gonioscopy and recurrent symptoms — this is pathologic and requires intervention. Observation alone risks progression to acute attack. 3. **Option 3 (Chronic angle-closure with prostaglandin analogs):** Prostaglandin analogs are used for open-angle glaucoma, not angle-closure. They may worsen angle-closure by causing anterior uveitis and iris swelling. Chronic angle-closure (synechial closure with elevated IOP and optic nerve damage) requires iridotomy ± filtration surgery, not medical therapy alone. ### Differential Diagnosis Summary | Type | Symptoms | IOP | Cornea | Gonioscopy | Management | |------|----------|-----|--------|-----------|-------------| | **Occludable angle** | None | Normal | Clear | Narrow, no closure | Prophylactic iridotomy | | **Subacute angle-closure** | Intermittent blurred vision | Normal/mildly ↑ | Clear | Appositional closure | YAG iridotomy | | **Acute angle-closure** | Severe pain, halos | >50 mmHg | Edematous | Synechial closure | Medical therapy + iridotomy | | **Chronic angle-closure** | Gradual vision loss | Elevated | Clear | Synechial closure | Iridotomy ± trabeculectomy | [cite:Khurana 6e Ch 12; Parson's Diseases of the Eye 22e Ch 10]