Glaucoma is generally classified into three main stages based on the level of vision loss and optic nerve damage: early, moderate, and advanced. Some systems also include a “pre-perimetric” or “suspect” stage.

Glaucoma Suspect (Pre-Perimetric Glaucoma)

At this initial stage, you are considered a “glaucoma suspect.” This means your glaucoma doctor has noted one or more risk factors, but there is no definitive optic nerve damage or vision loss yet.

• What it means: You may have higher-than-normal eye pressure (ocular hypertension) or your optic nerve may look slightly unusual. However, visual field tests are still normal.
• Symptoms: There are typically no symptoms at this stage.
• Treatment: Your doctor may recommend regular monitoring to watch for any changes. In some cases, if you have multiple risk factors, they might suggest starting treatment with pressure-lowering eye drops as a precaution.

   

Stage 1: Early-Stage Glaucoma

In early-stage glaucoma, there is clear evidence of optic nerve damage, but it is still minimal. You will likely not have noticed any changes to your vision in your daily life.

• What it means: An OCT scan shows slight thinning of the optic nerve fibre layer, and a visual field test may reveal small, subtle blind spots, usually in the peripheral (side) vision.
• Symptoms: Vision loss is not noticeable during everyday activities. Most people are completely unaware they have a problem.
• Treatment: The primary goal is to lower eye pressure to prevent further damage. This is typically achieved with:
  • Prescription eye drops
  • Laser therapy, such as Selective Laser Trabeculoplasty (SLT)

     

Stage 2: Moderate-Stage Glaucoma

At the moderate stage, the damage to the optic nerve is more significant, and vision loss becomes more apparent on visual field tests. You may start to notice some changes in your vision, although your brain is very good at compensating for them.

• What it means: The blind spots in your peripheral vision have grown larger or more numerous. The optic nerve shows more pronounced thinning.
• Symptoms: You might begin to experience a slight loss of side vision, although central vision usually remains clear. You may find yourself bumping into things or being surprised by objects in your periphery.
• Treatment: Treatment becomes more assertive to halt progression. Your doctor may recommend:
  • A combination of different eye drops.
  • Considering minimally invasive glaucoma surgery (MIGS) if drops and laser are not effective enough.

     

Stage 3: Advanced-Stage Glaucoma

In advanced-stage glaucoma, there is extensive damage to the optic nerve and significant loss of vision. At this point, vision loss can seriously impact daily activities.

• What it means: Visual field tests show large areas of vision loss, which may start to affect your central vision. This can lead to “tunnel vision,” where only a small central area of sight remains.
• Symptoms: You will have noticeable difficulty with peripheral vision and may have trouble seeing in low light or adapting to changes in brightness. Tasks like driving can become dangerous or impossible.
• Treatment: The focus is on preserving the remaining vision. Treatment is aggressive and may involve:
  • Maximising medication therapy.
  • More traditional glaucoma surgery, such as a trabeculectomy or the insertion of a glaucoma drainage device (tube shunt).

     

What About End-Stage Glaucoma or Blindness?

If glaucoma is left untreated, it can lead to end-stage glaucoma, which is defined by profound vision loss. In the most severe cases, this can result in total blindness. However, it is important to remember that with modern treatments and regular monitoring, blindness from glaucoma is preventable for most people.