Types Of Glaucoma: How The Main Forms Differ

Glaucoma is not a single condition. It is a group of eye diseases that damage the optic nerve, and the differences between them matter. Some forms develop silently over many years. Others come on within hours and are a medical emergency.

This guide compares the main types of glaucoma so you can see how each one behaves. For a general explanation of the disease, how it is diagnosed and how it is treated, see our guide to what glaucoma is.

The main types of glaucoma at a glance

Glaucoma is classified by how the eye’s drainage angle behaves and how quickly the condition develops. Here is how the main forms compare, with each explained in more detail below.

• Primary open-angle glaucoma: the drainage angle stays open but drains poorly. It develops over years and causes no symptoms until peripheral vision is affected, so it is usually picked up on a routine eye test.
• Acute angle-closure glaucoma: the drainage angle becomes suddenly blocked. Symptoms appear within hours and include severe eye pain, headache, nausea and halos around lights. This is a medical emergency.
• Chronic angle-closure glaucoma: the drainage angle closes gradually over months or years. There are often no symptoms at first, followed by gradual vision loss.
• Normal-tension glaucoma: the angle is open, and eye pressure sits within the normal range, yet the optic nerve is still damaged. It progresses over years, again without early symptoms.
• Secondary glaucoma: caused by another eye condition or an injury, so the angle, the speed of onset and the symptoms all vary with the underlying cause.
• Congenital glaucoma: the drainage system is malformed from birth. Signs appear in infancy and include enlarged eyes, a cloudy cornea, watering and light sensitivity. It needs urgent assessment.
• Pigmentary glaucoma: pigment granules shed from the iris block the drainage meshwork. It develops over years and is usually silent until vision is affected.
• Traumatic glaucoma: the drainage structures are damaged by an eye injury, either at the time or years later. Symptoms vary with the injury and often include eye pain and blurred vision.

Most forms are managed with routine monitoring once diagnosed. Two are different: acute angle-closure glaucoma needs emergency treatment, and congenital glaucoma needs urgent assessment in infancy.

Primary Open Angle Glaucoma (POAG)

POAG is the most common form of glaucoma, characterised by the gradual increase in eye pressure due to the slow clogging of the drainage canals. It is a lifelong condition, often detected during a routine eye exam before any noticeable vision loss occurs.

The main risk factors are being over 60, a family history of glaucoma and high blood pressure. Because peripheral vision is affected first, most people notice nothing until the condition is well advanced, when tunnel vision can develop. Treatment aims to lower eye pressure using drops, laser or surgery.

For a fuller explanation of this form, see our guide to open-angle glaucoma, or compare it directly with the closed-angle form in our guide to open-angle versus closed-angle glaucoma.

Angle Closure Glaucoma

This type, involving a sudden or gradual closure of the drainage angle, is less common but more urgent than POAG.

There are two forms, and they behave very differently: acute angle-closure glaucoma, which develops within hours, and chronic angle-closure glaucoma, which develops slowly over months or years.

Acute Angle Closure Glaucoma:

Symptoms include severe eye pain, blurred vision, headache, nausea and seeing halos around lights. This is a medical emergency: sight can be permanently lost within hours without treatment, so anyone with these symptoms should seek immediate medical attention rather than waiting for a routine appointment.

Treatment involves laser or surgical procedures to clear the blockage and lower eye pressure, most commonly a laser peripheral iridotomy.

For full detail on the warning signs, what to do during an attack and how it is treated, see our guide to acute angle-closure glaucoma.

Chronic Angle Closure Glaucoma:

Symptoms are similar to POAG, with more gradual vision loss. Treatment may involve eye drops, laser treatments or surgery.

Normal-Tension Glaucoma

In cases of normal-tension glaucoma, damage to the optic nerve can occur even when eye pressure is within normal levels. The exact cause is unknown, though reduced blood supply to the optic nerve due to high blood pressure or other vascular issues is suspected. Symptoms mirror POAG but without elevated eye pressure, and treatment focuses on lowering pressure further to slow the progression of optic nerve damage. You can read more about how pressure relates to the disease in our guide to what glaucoma is.

Secondary Glaucoma

This type is a result of an injury or another eye condition, such as cataracts or uveitis. It can be of the open-angle or angle-closure variety. Steroid-induced glaucoma and neovascular glaucoma are types of secondary glaucoma.

•     Symptoms: depend on the cause but often include elevated intraocular pressure.
•     Risk factors: eye surgery, injury, inflammation, and certain medications.
•     Treatment: depending on the underlying cause, treatment may involve medication, laser therapy or surgery. See our guide to glaucoma treatment in Australia for the options.

Congenital glaucoma

Present at birth, congenital glaucoma is due to an abnormal development in the eye’s drainage system. Seeking immediate medical attention is vital to prevent any potential loss of vision.

•     Symptoms: enlarged eyes, cloudy cornea, excessive tearing, and light sensitivity.
•     Risk factors: it is typically hereditary. Our guide to whether glaucoma is hereditary covers the family history question in more detail.

Pigmentary glaucoma

This arises when pigment granules from the iris shed and block the trabecular meshwork, causing increased eye pressure. This condition can sometimes be linked to pigment dispersion syndrome.

•     Symptoms: typically asymptomatic until vision loss occurs.
•     Risk factors: middle-aged, short-sighted men are most commonly affected.

Traumatic glaucoma

Caused by an injury to the eye, either immediately after the trauma or years later. Even minor injuries can lead to this type of glaucoma.

•     Symptoms: eye pain, blurry vision, and other symptoms vary based on the trauma.
•     Risk factors: direct injury to the eye or surrounding area.

Other types

•     Uveitic glaucoma: caused by uveitis, an inflammation of the eye’s middle layer.
•     Ocular hypertension: elevated intraocular pressure without optic nerve damage or vision loss, but it is a risk factor for glaucoma.

How do I know which type I have?

The type of glaucoma you have is determined by an eye examination, not by symptoms alone. Gonioscopy, a test that lets an ophthalmologist see whether the drainage angle is open or closed, is the test that separates open-angle from angle-closure forms. Eye pressure measurement, optic nerve imaging and visual field testing then establish how far the condition has progressed.

Our guide to eye tests for glaucoma explains what each test involves and what to expect at your appointment.

Frequently asked questions

Which type of glaucoma is a medical emergency?

Acute angle-closure glaucoma. It causes a sudden, painful rise in eye pressure and can damage the optic nerve within hours. Severe eye pain with headache, nausea and halos around lights needs immediate medical attention. Congenital glaucoma also requires urgent assessment.

Can you have more than one type of glaucoma?

Yes. Some people have a mixed mechanism, where features of both open-angle and angle-closure glaucoma are present. It is also possible to develop a secondary glaucoma on top of an existing primary form, for example after an eye injury or a course of steroid medication.

Do all types of glaucoma involve high eye pressure?

No. In normal-tension glaucoma, the optic nerve is damaged even though eye pressure sits within the normal range. This is one reason glaucoma cannot be ruled out by a pressure reading alone.

Is one type of glaucoma more serious than another?

They differ in how quickly they progress rather than in whether they are serious. Any untreated glaucoma can cause permanent vision loss. Acute angle-closure is the most time-critical because the damage happens within hours, while open-angle forms cause loss so gradually that they are often found on a routine eye test.

Talk to a glaucoma specialist

Understanding which type of glaucoma you have shapes how it is monitored and treated. If you have been diagnosed, have a family history, or are due for a check, our glaucoma specialists can assess your eyes and explain your options.

Contact Mornington Peninsula Eye Clinic on (03) 9070 3580 to schedule your appointment today.

Note: Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

References

https://www.mayoclinic.org/diseases-conditions/glaucoma/symptoms-causes/syc-20372839

https://www.aao.org/eye-health/diseases/what-is-glaucoma

https://glaucoma.org/learn-about-glaucoma/types-of-glaucoma/