Doctors use several systems to categorize how glaucoma progresses. Many doctors classify glaucoma as mild, moderate, or advanced. But some systems use a more detailed scale.

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Glaucoma is a condition characterized by damage to your optic nerve. It affects about 3 million people in the United States.

Glaucoma often doesn’t cause noticeable symptoms in the early stages. As the disease progresses, it may cause:

Experts have developed at least 20 glaucoma staging systems since the American Medical Association’s Glaucoma Staging System was created in 1958.

While no system is recognized as the gold standard, they all share some similarities. A higher stage correlates with more vision loss or structural damage to your optic nerve.

In this article, we look at some of the ways doctors stage glaucoma and how your stage affects your treatment.

Glaucoma is a progressive condition. Let’s look at how some of the staging systems measure this progression.

International Classification of Disease

The World Health Organization’s International Classification of Diseases is a widely accepted classification system for many medical conditions, including glaucoma.

In this classification system, doctors use a visual field test to divide your vision into three regions:

  • superior hemifield: the top half of your visual field
  • inferior hemifield: the lower half of your visual field
  • central 5 degrees: your central 5 degrees of vision

Glaucoma is staged from mild to advanced based on the results:

MildNo visual problem
ModerateProblems in either hemifield
AdvancedProblems in central 5 degrees or both hemifields

Hodapp-Parrish-Anderson method

The Hodapp-Parrish-Anderson method stages glaucoma based on two criteria:

  • the overall extent of damage using:
    • mean deviation, the degree of vision loss compared to the expected for your age
    • the number of areas of vision loss
  • the location of vision loss

This system divides glaucoma from early to severe based on these changes.

Mills system (GSS)

A 2006 paper by Richard Mills and others proposed a glaucoma staging system (GSS) developed from the Hodapp-Anderson-Parrish system. It’s one of the most common staging systems used in research, though not common in clinics.

It classifies glaucoma stages from stage 0 to stage 5.

0High pressure in your eye but no signs of visual loss
1Early glaucoma
2Moderate glaucoma
3Advanced glaucoma
4Severe glaucoma
5End stage, no vision in worst eye

Enhanced glaucoma staging system (GSS-2)

Later in 2006, the GSS-2 was developed from the GSS. It classifies glaucoma from stage 0 to stage 5 based on the results of a visual field test. It considers your degree of vision loss and the pattern of your vision loss.

Global glaucoma system (GGSS)

In a 2021 study, researchers introduced a new glaucoma staging system called GGSS. This system was developed based on the results of 350 cases of glaucoma. It considers:

  • the degree of damage to the retinal tissue surrounding your optic nerve
  • the degree of vision loss measured with visual field testing

GGSS divides glaucoma into:

  • normal
  • borderline
  • early damage
  • moderate damage
  • advanced damage
  • terminal damage

What does glaucoma staging mean for me?

Glaucoma is a progressive condition that can lead to complete vision loss if not managed properly. No matter what staging system your doctor uses, a higher stage correlates with a higher degree of vision loss or structural damage.

Your doctor can help you interpret what your glaucoma stage means and advise on steps to take minimize future vision loss. Many people never have noticeable vision loss if they effectively manage their glaucoma.

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With early detection and treatment, glaucoma doesn’t cause most people’s vision to change quickly enough to cause noticeable vision loss. It can take many years to decades for glaucoma to cause blindness.

About 3–17% of people are at risk of visual problems, even with treatment. People diagnosed at a young age are at a particular risk.

Doctors treat glaucoma primarily by lowering the pressure in your eye. The best treatment depends on the type and severity of your glaucoma. At this time, treatment aims to minimize future vision loss but can’t reverse damage.

If you have advanced glaucoma, your doctor may want to be more aggressive with your treatment. The primary treatment options include:

  • medications to lower eye pressure
  • laser treatment to help fluid drain
  • surgery

Symptoms of end-stage glaucoma

Advanced glaucoma may cause symptoms such as:

People with angle-closure glaucoma, a rare subtype, may also experience:

  • intense eye pain
  • tenderness around your eyes
  • seeing halos around lights
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Most people with glaucoma can maintain their vision with treatment or regular monitoring. About 10% of people have vision loss even with treatment.

Doctors stage glaucoma to help guide treatment decisions and predict its outlook. Experts have developed many staging systems for glaucoma but have yet to accept one as the gold standard.

In every glaucoma system, a higher stage represents a higher degree of vision loss or structural damage. Your eye doctor can help you determine your stage’s meaning and how to prevent vision loss best.