Acute angle-closure glaucoma (AACG) is a rare form of glaucoma with a quick onset, requiring immediate medical attention in order to avoid severe vision loss. It differs greatly from the much more common open-angle glaucoma, where internal eye pressure rises very slowly over the course of years. This video, created for medical students and other healthcare professionals, can help you understand AACG, how to recognize it, and what can be done about it.*

What is glaucoma and AACG? (:30)

Glaucoma is damage to the optic nerve from significantly increased intraocular (internal eye) pressure, or IOP. This rise in IOP is commonly caused by a blockage in the eye’s drainage system, called the trabecular meshwork. Blockages in the drainage system obstruct eye fluid, called aqueous humor, from exiting the eye.

In AACG, the blockage is caused by the iris bulging forward, closing off drainage inside the front eye chamber. Since eye fluid normally flows from the rear chamber into the front chamber, the fluid buildup increases pressure on the iris from behind.

AACG is a medical emergency requiring immediate treatment to avoid permanent vision loss.

Risk factors (2:05)

Risk factors for AACG include:

• Older age
• Female sex (women’s risk is about four times higher than men’s)
• Family history of AACG
• Chinese and East Asian ethnicity
• Shallow front eye chamber
• Medications like adrenergics, anticholinergics, and tricyclic antidepressants

Whereas Black people are at the highest risk for open-angle glaucoma, AACG is rare in this population.

Signs and symptoms (3:06)

A person with AACG will typically experience:

• Headache
• Nausea and vomiting
• Severe eye pain
• Eye redness
• Blurred vision

They may also see halos surrounding lights.

Diagnosing AACG (3:33)

During an examination, a person with AACG may present with:

• A teary eye
• A hazy cornea
• Decreased vision
• A firm, hard eyeball
• A dilated pupil in the affected eye, fixed in size and not responsive to light

Initial treatment (4:03)

According to the 2019 NICE Clinical Knowledge Summaries, physicians should refer patients with “potentially life-threatening causes of red eye” for same-day evaluation by an ophthalmologist. If there’s any delay, they advise, the patient should:

• Lie on their back (without a pillow)
• Be given IOP-lowering medications
  • Pilocarpine eye drops (2% for blue eyes, 4% for brown eyes)
  • Acetazolamide (500 mg orally)
• Be given analgesia for pain and, if necessary, an antiemetic for nausea and vomiting

Pilocarpine eye drops constrict the pupil and contract the ciliary muscles. These actions help open the drainage angle, or the space between the iris and cornea where the trabecular meshwork is. At the same time, acetazolamide reduces eye fluid production to balance the inflow and outflow.

Secondary care (5:46)

Once a patient is at the hospital and under an ophthalmologist’s care, AACG treatment may also involve more of the same eye drops, as well as:

• Timolol and dorzolamide to reduce fluid production, and/or
• Brimonidine to reduce fluid production and increase outflow

A common treatment for AACG is laser iridotomy, a surgical procedure that enables fluid to flow out of the posterior chamber by making a tiny hole in the iris. This reduces the forward pressure on the iris that was pushing the iris against the cornea, closing off the drainage angle.

GRF says AACG surgery is generally successful and long-lasting, though regular eye exams are still advised.

To help prevent AACG, GRF says a simple test can be done to determine whether the eye’s drainage angle is wide (normal) or narrow (abnormal). Get annual comprehensive eye exams to support optimal vision and eye health.

*Zero to Finals. (2021, January 19). Understanding Angle-Closure Glaucoma [Video file]. YouTube. Retrieved from https://www.youtube.com/watch?v=wHKo0CPtaMY