The word glaucoma doesn’t refer to a single condition. In fact, glaucoma encapsulates a group of eye conditions that damage the optic nerve—which transfers information from the eyes to the brain. The Glaucoma Research Foundation offers an overview of the most common types of glaucoma.*

Understanding the optic nerve

Damage to the optic nerve is caused by increased pressure inside the eye, called intraocular pressure (IOP). IOP usually results from improper drainage of eye fluids, though different types of glaucoma have different reasons for the impaired drainage. When the optic nerve is damaged, the result is permanent vision loss (partial or complete).

What are the primary forms of glaucoma?

The primary types of glaucoma include:

• open-angle,
• angle-closure,
• normal-tension, and
• congenital.

Open-angle glaucoma

Open-angle glaucoma affects about three million people in the U.S. It accounts for more than 90% of all glaucoma cases and is responsible for nearly two out of every 10 cases of blindness in black people. 

This type of glaucoma is:

• chronic and slow-progressing,
• usually asymptomatic until the optic nerve has sustained severe damage, and
• more likely to occur in people with hypertension (high blood pressure). 

With open-angle glaucoma, vision loss begins at the periphery of the eye, progressing later to the front and center of the eye.

Normal-tension glaucoma

Normal-tension glaucoma is a type of open-angle glaucoma that occurs in people with normal eye pressure. About one in three people with open-angle glaucoma have this type.  

High risk factors for normal-tension glaucoma include: 

• Japanese ancestry,
• family history of normal-tension glaucoma, 
• certain heart problems (including irregular heartbeat), and 
• low blood pressure. 

Experts don’t know what causes this type of glaucoma.

Angle-closure glaucoma

In angle-closure (or acute) glaucoma, the angle between the iris and cornea closes, blocking drainage. Pressure builds rapidly and can cause blindness in just a few days if not treated immediately.

Go to the emergency room if you suddenly experience: 

• intense eye pain,
• nausea, 
• red eyes, and 
• blurred vision.

Your doctor can provide laser treatment and medication to help drain the fluid. They may treat both eyes to prevent future issues—even if only one eye is currently affected. 

A non-acute variant of angle-closure glaucoma occurs more gradually and may not present any symptoms in the early stages. 

Congenital glaucoma

Congenital glaucoma is rare and occurs when the eye’s drainage canals develop incorrectly or incompletely. Symptoms are usually noticeable immediately after birth.

These include eyes that are:

• cloudy, 
• sensitive to light, 
• make extra tears, and 
• larger than normal.

If surgery is performed quickly, children with congenital glaucoma will generally not suffer permanent vision loss. 

Secondary glaucoma

When glaucoma is caused by a separate medical condition, it is called a “secondary glaucoma.” If caught early, secondary glaucomas can usually be slowed or halted with medications, laser treatment, and/or surgery. 

Types of secondary glaucomas include:

• Neovascular glaucoma: This occurs when the eye makes extra blood vessels that cover the point of fluid drainage. It’s usually caused by diabetes or high blood pressure, and those underlying cause(s) must be treated in order to reduce the eye pressure.
• Pigmentary glaucoma: Pigment from your iris can flake off and block eye fluid from draining. Young, white, near-sighted males are at higher risk. This condition is also called pigment dispersion syndrome. There is currently no way to prevent pigment from flaking.
• Exfoliation glaucoma: Another variant of open-angle glaucoma, exfoliation glaucoma progresses faster and can result in higher eye pressure.
• Uveitic glaucoma: Approximately 2 out of 10 people with uveitis (irritation and swelling of the eye) develop uveitic glaucoma. Experts think this is caused by the formation of scar tissue. Uveitis medications may also cause glaucoma, since corticosteroids can increase eye pressure. 

Additional information on the different types of glaucoma can be found on the National Eye Institute website.

*Glaucoma Research Foundation. (2020, June 2). Types of Glaucoma.

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