Closed Angle Glaucoma: Exam Essentials

Recognize closed angle glaucoma fast: anatomy, acute signs, gonioscopy, pilocarpine and laser peripheral iridotomy.

Reviewed for accuracyJuly 31, 20263 min read

Warm-up

Which symptom is most typical of acute angle-closure glaucoma?

Lesson

Closed Angle Glaucoma in 30 Seconds

Closed angle glaucoma occurs when peripheral iris blocks the trabecular meshwork, reducing aqueous outflow and raising intraocular pressure. Acute attacks cause sudden painful blurred vision and require urgent treatment. Chronic disease may progress quietly through synechial angle closure and glaucomatous optic neuropathy.

Why the Angle Closes

Closed angle glaucoma results from apposition or adhesion between the peripheral iris and trabecular meshwork, blocking aqueous outflow. The usual mechanism is pupillary block: resistance to aqueous flow through the pupil pushes the peripheral iris forward. Risk rises with increasing age, a shallow anterior chamber, short axial length and a thick or anteriorly positioned crystalline lens. These features are common in hyperopic eyes and occur more often in people of East or Southeast Asian and Inuit ancestry. Attacks are often precipitated by pupillary dilation, whether physiologic in dim light or pharmacologic from mydriatic or anticholinergic medications.

Acute Versus Chronic Presentation

Acute angle closure: sudden severe eye pain, redness, blurred vision, halos around lights, nausea and a fixed or poorly reactive mid-dilated pupil with markedly elevated intraocular pressure.
Chronic angle closure: gradual peripheral anterior synechiae formation and optic nerve damage, often without dramatic symptoms.
Acute angle closure is an ophthalmic emergency. Immediate pressure lowering limits irreversible optic nerve injury, and treatment should not be delayed for gonioscopy if the presentation is clinically clear.
Laser peripheral iridotomy is the definitive treatment for pupillary-block angle closure. It bypasses the pupil and flattens iris bombe.

4 Facts Exams Always Ask

Acute angle closure combines painful red eye, blurred vision or halos and nausea or vomiting. It can be mistaken for stroke or gastrointestinal illness because headache and systemic symptoms may dominate.
Gonioscopy is essential because it directly visualizes and grades the angle. It also identifies peripheral anterior synechiae.
In pupillary block, pilocarpine induces miosis and pulls the peripheral iris away from the angle. Use it after initial intraocular pressure reduction restores iris perfusion.
Avoid miotics in non-pupillary-block mechanisms, particularly lens-induced or malignant, also called aqueous misdirection, glaucoma. Ciliary muscle contraction can shift the lens-iris diaphragm forward and worsen closure.

The Classic Trap

The common exam error is to treat acute angle closure as only a red eye or only elevated intraocular pressure. The decisive pattern is painful red eye, blurred vision or halos, nausea and a fixed or poorly reactive mid-dilated pupil. Recognize the cluster, suspect angle closure, lower pressure urgently and arrange definitive treatment rather than delaying for routine red-eye management.

Clinical Pearl

A laser peripheral iridotomy treats pupillary block, not every angle closure mechanism. If the angle remains occludable after a patent iridotomy, think beyond pupillary block, such as plateau iris or a lens-related mechanism. After an attack in one eye, the fellow eye usually needs prophylactic laser peripheral iridotomy, since it commonly shares the same anatomic predisposition.

Check yourself

Checkpoint 1

After a patient has an acute primary angle-closure attack in one eye, what is usually recommended for the fellow eye?

Checkpoint 2

Which medication class can precipitate pupillary block angle closure in a susceptible anatomically narrow-angle patient?

Clinical case

A 67-year-old hyperopic woman develops severe unilateral eye pain, headache, nausea, halos and blurred vision after watching a movie in a dark theater. Her eye is injected, the cornea is hazy and the pupil is fixed at mid-dilation. Intraocular pressure is 58 mm Hg.

What is the definitive laser treatment for pupillary-block angle closure?

Explanation

Laser peripheral iridotomy creates an alternate pathway for aqueous to pass from the posterior to the anterior chamber, relieving pupillary block. It is the definitive laser treatment for most pupillary-block angle-closure cases.

Case discussion

This is acute pupillary-block angle closure in an anatomically crowded eye, precipitated by pupillary dilation in the dark theater. After urgent intraocular pressure lowering and supportive treatment restore iris perfusion, pilocarpine can help relieve pupillary block, but laser peripheral iridotomy provides the definitive treatment, and the fellow eye requires assessment for prophylactic iridotomy.

Sources & Reviewer Info

Reviewed by Vasilis Inglezis: Optometrist and Ocular Oncology Imaging Specialist, Ocular Oncology Center, Athens, Greece. Last updated July 31, 2026.

References

Murray D. "Emergency management: angle-closure glaucoma." Community Eye Health. 2018;31(103):64.

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