Your visual field refers to the total area that your eye can see when focused on a central point. Visual field testing allows your optometrist to measure how much vision you have in either eye and can help determine if you are experiencing any vision loss.
Visual field tests can also help identify eye diseases like glaucoma, various other diseases of the optic nerve as well as other neurological diseases that may affect the visual pathway. It can even help determine if someone suffered a stroke which affected the portion of the brain that is responsible for vision. If you think you are experiencing vision loss or are being affected by an eye disease, contact us to book an appointment — the professional eye care team at Stoney Creek Eye Care is here to help.
Identifying Eye Problems With Visual Field Testing
Visual field tests are designed to detect blind spots called “scotomas” and other vision problems related to peripheral vision. Eye and brain disorders can cause peripheral vision loss and other visual field abnormalities — receiving a visual field test can help detect these disorders early on so they can be effectively treated and managed.
The size and shape of a scotoma can offer insights into the presence of eye diseases and help your optometrist determine what the most effective treatment will be for your specific needs.
Visual field tests can also help detect defects including diseases of the retina, optic neuropathy, brain tumors, and stroke.
Types of Visual Field Testing
Automated Static Perimetry Test
An automated static perimetry test helps create a detailed map of where you can and can’t see. The most common kind of automated static perimetry test is called the Humphrey Field Analyzer.
In a Humphrey visual field test, your vision will be tested so that your optometrist can determine where you have blind spots. The test consists of a center fixation light and blinking test lights viewable through your side vision. Every time you see a light blink through the machine, you will be asked to press a button. The effectiveness of your visual field will be determined by your ability to detect dim blinking lights in various areas of your peripheral vision — upon completion of the test, your optometrist will have a map of your eyes that shows where your blind spots are.
This is called a “static” test because the lights you respond to do not move across the screen, but they blink with differing amounts of brightness at different locations. This allows the machine to find the dimmest light you can see at each location using your peripheral vision.
Confrontation Visual Field Test
In this simple test, you will be asked to look directly at an object that is focused at the center of your vision while one of your eyes is covered. Once you have focused on the object, your eye doctor will hold up different numbers of fingers that are viewable in your peripheral vision and ask you the amount that you see. This test is a common way to quickly screen for any problems with your visual field without the use of technology.
Kinetic Visual Field Test
This test is similar to static perimetry testing, but instead of blinking lights, this test involves a machine with moving lights that are viewable through your peripheral vision.
Frequency Doubling Perimetry
Frequency doubling perimetry uses optical illusions to check for any damage that your vision may have previously taken. Vertical bars, typically coloured black or white, will appear on a screen in front of you and flicker at varying rates; if you cannot see the vertical bars during parts of the test, it can signify that you have experienced vision loss in parts of your visual field.
This test is designed mainly to measure the electrical signals of light-sensitive cells in your retina called photoreceptors. During the test, your eyes will be dilated and you will be given numbing eye drops. Afterward, once the drops have taken effect, your eyes will be held open by an apparatus called a speculum and a device called an electrode will be placed onto your cornea. A bowl-shaped machine will then be used to flash varying patterns of light onto your eye, and the electrode will measure your eye’s electrical activity as a direct response to the light patterns.
Electroretinography tests typically check for visual field issues related to conditions involving the retina.
The Amsler grid is mainly used to assess the visual fields of people afflicted with age-related macular degeneration (AMD). It is effective at assessing AMD because the process of the test is focused on measuring the middle of your visual field, which is the area most affected by AMD.
The test involves viewing a pattern of straight lines that make a grid of equal squares. You will be required to look at a central point, like a dot or star, in the middle of the grid and you will be asked if any sections of the grid look warped, blurry, or completely blank.
How to Book a Visual Field Test?
Routine eye exams are important and your optometrist can help you detect any visual problems you may be experiencing. Visit us today and book an appointment to talk to our optometrist to determine when a visual test is advisable for you!