Other
Visual Field Test
A visual field test checks your full range of vision, including side (peripheral) vision, to detect blind spots from conditions such as glaucoma.
Quick answer
Visual Field Test: what it is and what the results mean
A visual field test (perimetry) maps how much you can see across your field of vision, including the edges. It detects areas of reduced or missing vision that you may not notice yourself.
- Why it is done: It is used to diagnose and monitor glaucoma, to investigate other eye and optic nerve conditions, and to detect visual field loss caused by problems in the brain, such as after a stroke.
- Understanding results: The test produces a map of your field of vision, highlighting any blind spots or areas of reduced sensitivity.
What it is
A visual field test (perimetry) maps how much you can see across your field of vision, including the edges. It detects areas of reduced or missing vision that you may not notice yourself.
Why it is done
It is used to diagnose and monitor glaucoma, to investigate other eye and optic nerve conditions, and to detect visual field loss caused by problems in the brain, such as after a stroke.
What to expect
You look into a bowl-shaped machine and focus on a central point while small lights flash in different positions. You press a button each time you see a light, one eye at a time. It takes a few minutes per eye and needs concentration.
Understanding the results
The test produces a map of your field of vision, highlighting any blind spots or areas of reduced sensitivity. Patterns of loss help diagnose the cause and, when repeated over time, show whether a condition is stable or progressing.
Good to know
Risks and limitations
It is completely safe and painless. Results depend on concentration and cooperation, so tiredness can affect them, and the test is often repeated to confirm reliable findings.
Education and reference only. This explains the test in general terms and is not medical advice. Always follow the specific instructions from the team arranging your test, and discuss your results with your clinician.
Answers
Visual Field Test: frequently asked questions
Why is a visual field test used for glaucoma?
Glaucoma tends to damage peripheral (side) vision first, often without you noticing. The test detects this early loss and, when repeated, shows whether treatment is keeping the condition stable.
What if I miss some of the lights?
Missing a few lights is normal and expected — the test is designed to map the edges of your vision. Consistent patterns of missed spots, not occasional ones, are what matter.
Related tests
Other other investigations
Sources
Where this is drawn from
- NHS — Tests and treatments
- NICE — diagnostic guidance
- Relevant royal college / professional body
Building patient-education content for tests or procedures?
We create clear, accurate, referenced medical explainers and decision aids for teams.