Your Visual Field Test Results

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A visual field test measures your entire field of vision. This is the range of what you can see:

  • Above
  • Below
  • On either side of you

The test is done while your gaze is fixed on a central point directly in front of you.

This test can help find 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.

There are several types of visual field tests. The simplest are done as a standard part of an annual eye exam.

Depending on the results, your eye doctor may have you repeat the test. You may also need to do additional testing. Frequent visual field tests often are often done to monitor the progression of glaucoma.

This article looks at visual field tests, how they are performed, and how the results are interpreted.

An eye exam seen through eyeglasses

Chakrapong Worathat / Getty Images

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

What Is a Visual Field Test?

Your visual field is measured in degrees. Four quadrants are used:

  • Temporal: toward your ear
  • Nasal: toward your nose
  • Superior: upper, or above center
  • Inferior: lower, or below center

A normal visual field measures about:

  • 90 degrees temporally
  • 50 degrees superiorly and nasally
  • 60 degrees inferiorly

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

Different parts of the nervous system and brain control different parts of your visual field. The vision pathway includes everything from your retina to optic nerves to the cortex of your brain. Different patterns of vision loss are found with diseases that affect different parts of the vision pathway, such as:

Certain patterns of vision loss can point to regions where there may be a problem. For example, congruity occurs is when the field of vision defect in both eyes is similar. Increasing congruity usually means there is a problem in higher cortical parts of the brain. 

A loss of function in the lower visual field can point to problems elsewhere. This is usually associated with fibers of the upper retina or nerve head.

An abnormal test result may suggest a problem with your central nervous system, or point to an undiagnosed health problem. It may also detect:

  • Central or peripheral retinal disease
  • Some eyelid conditions including ptosis or drooping eyelid
  • Optic nerve disease
  • Diseases affecting the visual pathways within the brain

Causes of an abnormal visual field test result include:

Recap

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.

Types of Visual Field Tests

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.

Confrontation Visual Field Test

During this test, the healthcare provider or technician sits at eye level in front of the patient. The patient covers one eye. 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. Both eyes are tested separately.

Static Automated Perimetry

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.

Kinetic Perimetry

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.

Frequency Doubling Perimetry

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.

Amsler Grid

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.

Recap

There are a few different types of visual field tests. Some are done manually, while others are computerized. 

Interpreting the Results of Your Visual Field Test

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:

  • Gray-scale map: Darkened areas in a gray-scale chart show the parts of your vision field that may have vision loss or blurred vision.
  • Decibel scale: Test results are measured in decibels (dB). The scale shows a range of sensitivities at different test locations. The range of the scale depends on the type of test. It also depends on the patient's age. It may go from 0 dB, which indicates an inability to see intense light, to up to 32 dB.
  • Mean deviation (MD): This is the average difference between the patient's overall visual field sensitivity compared to people who see "normally" in the same age group. The mean deviation value becomes more negative as the overall field vision gets worse. Normal values are typically within 0dB and -2dB. OdB is no different from normal vision. Below -2dB may indicate a problem with vision.
  • Total deviation (TD): These charts show all parts of a person's visual field that differ from people who see normally in the same age group. The numbers show the difference between the patient's test results and what is expected for their age. Black squares are more likely to show abnormal vision than lighter gray shading.
  • Pattern deviation (PD): This shows more local deviation results and how much the shape of a patient's field differs from normal. Pattern deviation charts can be useful in tracking changes in a glaucoma-related vision problem.
  • Visual field index (VFI): This is similar to the mean deviation. It gives a percentage for overall vision. A VFI of 100% indicates perfect vision. 0% means there is no measurable vision.

Recap

Visual field test results are often presented in charts. These charts give healthcare providers detailed information about where your vision loss is and how your vision compares to other people your age.

What Happens After Your Visual Field Test?

If you have abnormal results, your healthcare provider may order additional tests. You may also be referred back to your primary care healthcare provider. Depending on your results, you may need to see a specialist, such as a neurologist or endocrinologist.

The next stages of testing might involve brain imaging or blood tests. Blood tests screen for conditions like:

Monitoring Glaucoma

Most types of glaucoma begin with loss of peripheral vision. The visual field test is often used to:

  • Diagnose glaucoma
  • Determine how severe the condition is
  • Monitor its progression 

If glaucoma is suspected, 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 may seem repetitive, but it 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.

Recap

Depending on your test results, your eye healthcare provider may refer you back to your primary care doctor or to a specialist. You may need follow-up tests or long-term monitoring.

Summary

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. 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.

Frequently Asked Questions

  • How long does visual field testing take?

    About five to 10 minutes.

  • How often do I need to have a visual field test if my eyes are healthy?

    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. Adults with no signs or risk factors for eye problems should have a baseline exam at age 40. If they're found to be healthy, they should have an exam every two to four years until age 54. People 55 to 64 should have an eye exam every one to three years. Those 65 and over should have one every one to two years.


  • How often should I have a visual field test if I have glaucoma?

    Once you've been diagnosed, your ophthalmologist 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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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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