What is Visual Field Testing, Its Procedure & Types?

Dec 01, 2022

When you look at one spot, you can see what is straight ahead, below, above, and on either side. The entire area we see at a glance is called a visual field. Visual field testing measures the distance the eye can see in any direction without moving and sensitivity in the different parts of the visual field. This test helps doctors to identify some diseases, such as glaucoma and specific types of injuries inside the eye.

You can receive a visual field test near you. Yorkdale Eye Care has an optometrist in North York, Toronto, where they offer visual field testing in North York, ON.

The Procedure of a Visual Field Test

During an eye examination, visual field testing is conducted on one eye at a time. When one eye is being tested, the opposite eye is completely covered to ensure the results are accurate.
The patient looks straight ahead throughout the testing as directed by the eye specialist to precisely map the peripheral visual field.
Most modern devices used for visual field testing can continuously monitor the ability of a patient to gaze at a single spot.

Types of Visual Field Tests

Confrontational Visual Field

The person conducting the test sits about 3-4 feet away, facing them. This test is designed to test a patient’s peripheral vision.
The tester stretches their arms straight on both sides and asks the patient to look straight ahead. The tester moves one hand, and the patient is to give a signal immediately after seeing the hand.

Amsler Grid

The Amsler grid entails a pattern of straight lines that make uniform squares. A large dot goes in the middle of the grid, and the patient must look at it and describe areas where the lines forming the squares look broken, wavy, or blurry.
This test examines the middle of the visual field and gives the doctor useful information any abnormalities or issues in that part of your eye.

Automated Perimetry

In this test, the patient sits on a chair with the head staying still. The forehead and the chin rest on a the device.
The patient looks at a source of light from which tiny lights of varying forces are flashed randomly in their visual field.

Electroretinography

This test utilizes the retina’s electrical activity emitted by the photoreceptor cells. A strobe light triggers the eye.
An electrode inside the cornea captures the measurement, and a graphic recorder (electroretinogram) is formed. The interpretation helps diagnose many hereditary and acquired disorders in the retina.

Static Automated Perimetry

Pinpoint flashes of light of varying sizes and brightness project into a vast white bowl.
The patient focuses on the middle of the bowl and presses a button when a light is in peripheral vision.
The machine uses the data obtained from the patient’s buttons and sophisticated software to interpret the data and give accurate results.

Kinetic Perimetry

Moving targets of different light sizes and intensities are used for this test. The patient shows when they appear in the peripheral vision.
The data obtained maps the entire visual field.

Frequency Doubling Perimetry

This test uses different intensities of a flickering image to test the visual field. It’s beneficial in identifying early glaucoma signs.
It produces a result based on optical images created with upright bars of differing colors, usually black and white, like a screen.

Conclusion

Once the visual field test has been conducted, the results are discussed with the patient by the doctor. A standard visual test means the patient can see appropriately across the board. Results showing visual field loss mean that some areas are less sensitive. It can mean vision loss in a small or large section. The results help the optometrist to give an accurate diagnosis and identify some issues early on. This test can help to diagnose conditions such as glaucoma, optic glioma, macular degeneration, brain tumor, and many other diseases.