Visual Field Test: What You Need to Know
A visual field test is a subjective gauge of the quality of a person’s central and peripheral vision. The purpose of the test is to create a separate map for each eye, which details its field of vision and identifies potential blind or weak spots.
A basic, or confrontation visual field test consists of the doctor instructing the patient to look straight ahead, and the doctor will judge the response to manipulating targets (such as the number of fingers being held up) within the patient’s peripheral vision. Doctors may also use an amsler grid, which judges visual scope from a printed image.
A computerized visual field test, also known as static automated perimetry, uses flashes of tiny dots of light within a spherical screen. Each eye is tested separately, and patients are instructed to look straight ahead and click a button whenever they see a flashing dot of light. The computer uses this feedback to create detailed maps of the patient’s peripheral vision.
The kinetic perimetry test, also known as a Goldmann perimeter, is an additional computerized visual field test using a different machine. This test focuses on capturing a map of the entire perimeter of the normal scope of vision (120 degrees vertically and 160 degrees horizontally). This test utilizes moving light flashes of varying sizes, with the patient clicking as they become visible.
The most common use of the visual field test is to search for early signs of glaucoma or detect if glaucoma has damaged the optic nerve. Loss of peripheral vision can serve as an early indicator of glaucoma, and the visual field test is also useful for effectively monitoring response to glaucoma treatment. Computerized visual field tests are the most useful for these diagnostic and monitoring purposes.
Visual field tests can also detect other eye conditions, such as ptosis (drooping of the eyelid), diseases of the retina, damage to the optic nerve due to other medical conditions, detecting conditions that impact image transit from the optical nerve to the brain, toxic response to certain medications, and other factors that can impact a patient’s central and peripheral vision.
In cases of temporary or permanent vision loss, a visual field test can help identify one of the causes in order to seek the most effective treatment.
Who Provides Visual Field Testing?
Medical visual field testing is most often performed by an ophthalmologist (medical doctor specializing in conditions of the eye) or a neurologist (specialist in nervous system).
If you notice vision loss, schedule an appointment with your local eye doctor, who will give you a full examination and then determine if you need visual field testing. At the Dr. Myers Eye Care Center, we offer advanced computerized visual field testing along with decades of experience treating glaucoma and symptoms of vision loss.