Visual Field Test: How It Works and What the Results Mean

Jul 08, 2023

A visual field test is part of a comprehensive eye exam and part of a neurological examination. This non-invasive test examines your fields of vision, and it is important for identifying vision problems that could be signs of eye disease or conditions that affect the brain (like a stroke). If your visual field test is not normal, you may need additional follow-up testing, as well as treatment.

A visual field test can help diagnose scotomas, or blind spots. It can also help identify loss of peripheral or side vision. Loss of side vision is an indicator of glaucoma, a disease that can lead to blindness.

This article describes what to expect during a visual field test, why it's done, and what the results mean.

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Annual visual field testing is usually covered by vision insurance. For people who've been diagnosed with glaucoma, insurance may cover at least two tests per year. If you are uninsured, discuss the costs upfront with your doctor.

Visual field testing is done while your gaze is fixed on a central point directly in front of you to assess what you can see straight ahead, on the sides, and up and down.

Four quadrants are used:

A normal visual field measures about:

One eye is tested at a time. This is because the visual fields of the eyes overlap. Visual pathways carry information from the eye to the visual part of the brain. There, the information is processed into vision.

Your vision relies on your retina, optic nerves, and your brain. Vision loss occurs due to diseases that affect any part of this pathway.

Certain patterns of visual field loss can help identify the cause of your vision problem and may detect subclinical (not causing symptoms yet) problems.

One eye or both eyes can have a visual field defect:

Causes of abnormal visual fields include:

A visual field test measures how well you can see above, below, and on either side of you. This test can help diagnose diseases of the eye, optic nerve, and central nervous system.

Methods for testing visual field vary. Some simple screening tests can be done in a few minutes during a regular vision check-up. Other tests are more complicated and comprehensive computerized tests.

During this test, the healthcare provider or technician sits at eye level in front of the patient. Each eye is tested separately as the other eye is covered.

The tester holds up one, two, or three fingers in one of four parts of the visual field. The patient focuses on one of the tester's eyes and tries to determine how many fingers are being held up.

During this test, the patient looks directly at a central point within a dome. A machine presents flashing lights of different sizes and brightness in different parts of the visual field. The machine gradually increases the size or brightness of the lights. The patient pushes a button when the lights become visible.

The results of this test aren't always perfect. A patient's eye might wander from the central point, for example, or the patient might accidentally push the button before seeing the light. For that reason, this test is usually repeated two or three times in one session. Because automated visual field testing machines are computerized, the test results can be tracked. The computer can use certain calculations to rule out errors.

During this test, the patient looks at a central point. A light is presented in the peripheral vision and is moved toward the central point. The patient pushes a button when the light becomes visible.

This test may be done on a screen or manually. The manual technique is called Goldmann kinetic perimetry.

Kinetic perimetry may be used to find vision problems located in the central nervous system. This includes visual changes caused by a stroke or optic neuritis.

During this test, a compact machine presents flickering images in varying intensities. The patient presses a button when the images can be seen. This type of machine is also used to test for glaucoma.

The Amsler grid is a simple pattern of squares with a dot in the middle. It is often used to test for central vision field problems.

During this test, the patient focuses on the dot with one eye at a time. If parts of the grid appear distorted, blurry, dark, or blank, it can indicate a visual field deficit. The Amsler grid is often used to test for macular degeneration.

Test results are often presented in charts. These charts show the range of sensitivity, or how well you can see in different parts of your field of vision.

The charts may include:

If you have abnormal results, your healthcare provider may order additional tests. Depending on your results, you may need to see a specialist, such as a neurologist or an endocrinologist.

The next stages of testing might involve brain imaging or blood tests.

Blood tests screen for conditions like:

Imaging tests may include brain imaging, such as a brain MRI. Sometimes visual evoked potentials may be ordered to assess nerve function.

Most types of glaucoma begin with loss of peripheral vision. If you have signs of glaucoma, your healthcare provider will probably order a visual field test. The data will help determine how severe your glaucoma is and how far it has progressed.

After your diagnosis, you will likely do a visual field test two or more times a year. This helps your healthcare provider understand how the disease is progressing. It also helps your healthcare provider decide if you need any changes to your medication.

A visual field test is often done as a part of an annual eye exam. It helps your healthcare provider understand how well you can see above, below, and on either side of you.

The results of these tests can point to specific types of vision loss. They can also help doctors monitor the progression of glaucoma.

There are a few different types of visual field tests, and they are all non-invasive. Some are done manually; others are computerized. The results of these tests can help your healthcare provider understand where your vision loss is and how it compares to other people your age.

Depending on your test results, you may need to be referred to a specialist. Follow-up tests may be ordered. If you have glaucoma, you may need to do visual field testing a couple of times a year. This helps your doctor monitor the progression of your disease.

About five to 10 minutes.

Visual field testing is part of a regular comprehensive eye exam. The American Academy of Ophthalmology recommends regular exams at specific intervals based on age.

Once you've been diagnosed, your eye doctor may want to do a visual field test within three to 12 months. This helps monitor how the disease is progressing. After that, you may need to be tested once or twice a year.

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By Troy Bedinghaus, ODTroy L. Bedinghaus, OD, board-certified optometric physician, owns Lakewood Family Eye Care in Florida. He is an active member of the American Optometric Association.