A 58-year-old woman presents to the emergency department with acute onset of severe eye pain, blurred vision, and halos around lights in her right eye for the past 6 hours. On examination, the cornea is hazy, the pupil is mid-dilated and fixed, and intraocular pressure is 52 mmHg. Clinical suspicion for acute angle-closure glaucoma is high. Which investigation is most appropriate to confirm the diagnosis and assess the fellow eye?

Explanation

## Diagnostic Confirmation in Acute Angle-Closure Glaucoma **Key Point:** Gonioscopy is the gold standard investigation for confirming angle-closure and assessing the anatomical status of the drainage angle in both eyes. ### Why Gonioscopy is the Investigation of Choice Gonioscopy allows direct visualization of the anterior chamber angle and confirms: - **Angle closure** — appositional or synechial contact between iris and trabecular meshwork - **Severity** — extent and location of angle closure - **Fellow eye status** — critical for risk stratification and prophylactic treatment **High-Yield:** In acute angle-closure, gonioscopy must be performed on BOTH eyes: - Affected eye: confirms diagnosis and documents extent of closure - Fellow eye: identifies narrow angles at risk of acute attack (50–60% bilateral risk) ### Gonioscopy Findings in Acute Angle-Closure | Finding | Significance | |---------|-------------| | Appositional closure | Reversible; may open with treatment | | Synechial closure | Permanent iris-trabecular adhesions | | Peripheral anterior synechiae (PAS) | Indicates chronicity; poor prognosis for angle reopening | | Narrow angle in fellow eye | Indication for prophylactic laser peripheral iridotomy | **Clinical Pearl:** Gonioscopy in acute angle-closure is typically performed AFTER initiating medical therapy to lower IOP and clear the hazy cornea, improving visualization. However, it remains the definitive diagnostic test. **Mnemonic — GONI:** **G**old standard, **O**pens the angle view, **N**ecessary for **I**ris-trabecular assessment.