Visual field tests are often used by ophthalmologists to determine how eyelid abnormalities like ptosis and sagging eyelids may impede vision.
1. Visual Field Test in a Confrontation Situation
A confrontation visual field test is a typical approach for your doctor to check for issues in your visual field. One of your eyes will be covered while you look directly at an object in front of you (such as the doctor’s nose). As you look at the object in front of you, your doctor may hold up various numbers of fingers in different parts of your peripheral (side) vision field and ask how many you notice.
2. An Automated Static Perimetry Test
Your ophthalmologist will use more specialized tests to examine how you view items in your range of vision to check for a suspected eye condition or monitor the progression of eye disease. This is accomplished through the use of an automated static perimetry test. It aids in the creation of a more detailed map of what you can see and what you can’t see.
To do this test, look into the center of a periphery, which is a bowl-shaped instrument. A patch will be placed over the eye that will not be examined. Your lens prescription will be placed in front of the testing eye to ensure that you see as clearly as possible.
Throughout the exam, you will be required to keep your gaze fixed on a central target. Small, dim lights will appear in various locations within the bowl, prompting you to click a button anytime you see one. The machine keeps note of which lights you missed.
During the exam, you may blink normally. You can also pause the test if you feel like you need to take a break. Your doctor can detect which lights you see outside your central field of vision because you are gazing straight ahead during the exam. Because glaucoma affects peripheral vision, this test might reveal if you are losing vision outside of your core visual field.
Because the lights do not travel across the screen but instead blink with varying degrees of brightness at each position, this is referred to as a “static” test. This enables the machine to locate the dimmest light you can see in each of your peripheral vision locations.
Some of the lights on the machine will be too faint for you to see. This is done on purpose to determine each location’s “visual threshold,” or the brightness at which you have difficulty seeing half of the time. You may be anxious because you are unable to see all of the lights. Do not worry; this is how the test is intended to go.
3. Visual Field Kinematics
In some situations, you may be subjected to a procedure known as kinetic visual field testing. The kinetic test is similar to the perimetry testing technique mentioned above, but instead of blinking lights, it uses moving light targets.
4. Perimetry of Frequency Doubling
Frequency doubling perimetry is another method your ophthalmologist might use to assess vision loss. It checks for eyesight damage via an optical illusion. On the perimeter screen, vertical bars (typically black and white) appear. The rate at which these bars flicker will vary. It could indicate vision loss in certain portions of your visual field if you are unable to see the vertical bars at certain periods during the test.
5. Electroretinography (ERG)
Electroretinography may be used by your ophthalmologist to check for visual field loss caused by certain retina disorders. This test examines the electrical impulses of photoreceptors, which are light-sensitive cells in the retina, as well as other cells. Your eyes will be dilated, and you will be given numbing eye drops to do this test. A device known as a speculum is used to keep your eyes open. An electrode is a little device that is implanted on your cornea. Flashing or shifting patterns of light will be sent into a bowl-shaped machine. The electrode records the electrical activity of your eye in reaction to light.
6. The Amsler Grid Is a Simple Visual Field Test for Central Vision
The Amsler grid is a fairly basic sort of visual field exam that people with age-related macular degeneration (AMD) are familiar with. It is a grid of numerous equal squares made out of a pattern of straight lines. You describe any places that appear wavy, hazy, or blank by looking at a dot in the middle of the grid.
People with AMD frequently utilize the Amsler grid at home. This test assesses the middle of the visual field, but it is a quick and easy way to track vision improvements.