Acute angle-closure glaucoma (AACG) refers to a rare condition in which intraocular pressure (IOP) in the eye increases rapidly. It is a serious condition that builds up pressure within hours. This pressure may harm the optic nerve leading to loss of vision if emergency treatment is not sought. 

AACG develops as a result of fluid in the eye that refuses to drain away. It is this fluid that quickly builds up pressure to cause AACG. AACG patients have an anterior chamber (located at the front of the eye covered by the cornea) that is smaller than average. Where the cornea and iris meet is the angle at which the trabecular meshwork (tissue) is located. In a normal eye, this angle is about 45 degrees. 

However, in AACG patients, the angle is narrower such that the iris moves closer to the trabecular meshwork. As the lens age, they increase in size. The aqueous humor (fluid in the eye) is then unable to move between the iris and the lens as it travels to the anterior chamber. This is what causes the build up of pressure at the back of the iris. The increased pressure forces the iris against the trabecular meshwork causing a complete blockage. This sudden blockage results in AACG.

Also Known As

  • Acute glaucoma
  • Narrow-angle glaucoma
  • Closed-angle glaucoma


  • Primary angle-closure glaucoma(caused by pupillary block)
  • Secondary angle-closure glaucoma (caused by other eye diseases)

Causes and Risk Factors

AACG is a hereditary disease. It is possible for several members of one family to be afflicted. 
An attack of AACG may occur if the eyes dilate excessively or quickly. The eyes dilate when a person:

  • Gets stressed or excited
  • Enters a dark room
  • Takes certain medications such as antihistamines
  • Uses eye drops to dilate the eyes

Some health conditions such as farsightedness, cataracts, diabetic retinopathy, etc., may cause AACG. 
Individuals between ages 55 and 65 are more likely to be affected. So are people of Asian descent. Women are also more likely to have AACG than men.

Signs & Symptoms

The symptoms of AACG include:

  • Severe pain in the eye
  • Very blurry images
  • Seeing halos around lights
  • Severe headache
  • Nausea and vomiting
  • Red eyes
  • Sudden loss of vision
  • Unmoving dilated pupil
  • Corneal edema (swelling of the cornea)
  • Engorged conjunctival vessels (vessels congested with blood)


The eye care professional will check the IOP and also determine if the angle is normal or abnormal. He/she may use:

  • Tonometry
  • Tonometry is an instrument which measures the pressure in the eye.
  • Ophthalmoscopy
  • A small lighted device that determines the damage to the optic nerve.
  • Gonioscopy
  • A slit lamp (microscope) is used to look into the eye to get a view of the angle anatomy. 
  • Pachymetry
  • It measure corneal thickness because thin corneas can cause AACG.
  • Retina check
  • Photographs or scans are taken to detect changes over time.
  • Perimetry
  • This test establishes if the field of vision has been affected by glaucoma.


Treatment of AACG aims to reduce pressure in the eye by unblocking the drainage canals.

Medical Treatment

The eye doctor will prescribe eye drops that narrow the pupil. He or she may also prescribe medications that lower the amount of fluid produced in the eye. A single or a combination of medication can reduce the pressure in the eye. 
Non-invasive alternatives have been developed to reduce pressure in the eye. Examples include:

  • The ExPress mini glaucoma shunt. This device diverts aqueous humor from the anterior chamber thus lowering IOP. 
  • The Trabectome. It lowers IOP by reducing resistance to the outflow of aqueous humor. 
  • Canaloplasty. It reduces IOP by improving aqueous circulation through the trabecular outflow process.

Surgical Treatment

Using laser peripheral iridotomy (LPI), an opening is made through the iris. This allows clear direct passage for aqueous liquid to flow directly into the anterior chamber. 

Conventional surgery by use of trabeculectomy is also used to release pressure in the eye. The surgeon makes a way in the sclera (the white of the eye) to remove unwanted fluid.

Drainage implant surgery is recommended for patients with scarring. This surgery is also for those whose IOP could not be handled by traditional surgery. The method uses several devices designed to help the drainage of aqueous humor.

Prognosis/Long-term outlook

Patients with AACG must continue with treatment for life. There is no cure. The patients must stick to the medication regime. 

Prevention/Follow Up

AACG can be prevented by doing regular checkups. If signs of an imminent attack are evident, the doctor may use laser surgery to stem it off. People aged 40 and above are advised to go for these checkups.

AACG patients who are on treatment should also go for continuous checks because the disease can progress or change without warning.