A visual field test is a way to measure what you can see above, below and all-around. Visual field tests are specifically used to detect areas of vision loss (blind spots). If you have previously had vision loss problems, these tests can also be used to monitor the progression.
What is a visual field test?
A visual field test is a simple test which measures your peripheral vision and all-around vision. The visual field machine will complete an analysis of the responses given during the test and collate these results in a visual plot field.
Why do I need a visual field test?
Your optometrist uses the visual plot field to compare your visual field test to others from people of a similar age, as well as looking for any loss of sensitivity across the visual field. This is split into two types: diffuse and localised. You can find out more about visual field test results interpretation here, including what an abnormal visual field test means.
What does a visual field test show?
The visual field machine will complete an analysis of the responses given during the test and collate these results in a visual field plot. This information will be used to look for any loss of sensitivity across the visual field. This is split into two types: diffuse and localised.
What can a visual field test detect?
A visual field test can detect vision loss caused by a possible brain tumour, stroke or eye diseases such as glaucoma or diabetic retinopathy.
Diffuse vs localised visual field test
A diffuse visual field defect happens when the overall sensitivity of the eyes is lower than average. This type of defect is commonly caused by a cataract, but it could also be due to not wearing the correct glasses during the test. That’s why your optometrist will consider your visual field results along with the results from other tests carried out during your eye exam.
A localised field defect happens when a particular area of the visual field has reduced sensitivity, so it’s harder for that person to detect the lights appearing in that location. There are certain patterns of localised visual field defects that are typical of different eye diseases, including glaucoma.
What is a normal visual field test result?
A normal visual field test means that someone can see well through the centre and around the edges of their vision. It is measured in degrees from the central point in four quadrants, which are called the temporal, nasal, superior and inferior. A normal visual field test result measures 90 degrees temporally, 50 degrees superiorly and nasally, and 60 degrees inferiorly. You can find out more about visual field test results here.
What does an abnormal field visual test mean?
If you have a glaucoma-suspicious visual field defect, your optometrist will investigate this thoroughly. An abnormal visual field test could indicate early signs of glaucoma, but further tests will need to be done to confirm this. It’s important to note that many people who are not familiar with a visual field test, or perhaps did not understand the test fully, can find it difficult on their first attempt.
Sometimes the optometrist will ask for the test to be repeated, or run some more tests, in order to see if there is a consistent defect. It’s generally only repeatable field defects that may be a cause for concern.
These tests may include:
- Tonometry
- Retinal photography
- Optical coherence tomography (OCT)
- Visual acuity
Noticed a change in your vision?
If you’re not sure whether you need glasses, or you’ve had a sudden change in your eyesight, a field vision test can help by measuring your all-around vision and detect any vision problems you might have. Symptoms of eye problems are not always obvious, so it’s important to have your eyes tested regularly.
For more information, visit our eye test hub, or book an appointment at your local store.
