Tell me about glaucoma

Glaucoma vision loss is different

You are probably familiar with traditional eye tests that check your vision to see if you need glasses.

A traditional eye test, in isolation, is not enough to see how glaucoma is affecting your vision. Other tests such as the visual field test are also performed.

Tell me how glaucoma affects vision

People with glaucoma have regular visual field tests. These may show what field of vision you have, and what you might have lost, because of glaucoma.

This information helps your eye specialist monitor your glaucoma and tailor your treatment. Their goal is to stabilise your vision and protect against sight loss for as long as possible.

Understanding vision

For illustrative purposes only

Your eyes work together with your brain to give you a field of view. Each eye has a different view of the world. What you see with your eyes is called your visual field.

For illustrative purposes only

Your eyes can have surprisingly different visual fields. A ‘good’ eye can compensate for a ‘bad’ one so your overall vision isn’t affected, but the eye with glaucoma still needs treatment.

For illustrative purposes only

When both eyes have the same part of their visual field damaged part of your vision will be ‘missing’.

Visual fields are measured using a machine like this.

For an example of what the test feels like, download the Glaucoma in Perspective app on your iPad or tablet.


For illustrative purposes only

The test usually produces a separate visual field map for each eye. The following images show how this information is combined. Sometimes the visual field for both eyes is assessed at the same time.

For illustrative purposes only

The darker areas are where your eye has failed to see the small spot of light.

For illustrative purposes only

Your brain combines information from both eyes which created what you see.

What do these visual fields tell us?

If one eye’s visual field is completely black but the other is fine, your combined visual field won’t be affected.

You can see that because of the variety of different visual field patterns possible, everyone’s experience of glaucoma will be different.

If visual fields are black in similar areas, your combined visual field will also be black. It’s the overlapping black areas in the right and left eye that matter.