Visual Field Testing

The visual field is how much of an area your eye can see when you focus on a central point. If you’ve started experiencing issues with vision in one or both eyes, your Ophthalmologist will conduct a Visual Field Test to measure your vision range and determine if you may be suffering from a range of conditions or diseases that disturb normal vision. An array of visual field tests may be administered to diagnose a wide range of eye conditions and diseases. Central and peripheral vision testing is recommended for all new patients and often recommended alongside routine eye examinations.

Confrontation Visual Field Test

An extremely common way of testing visual acuity, the confrontation visual field test involves having the patient look directly at their Ophthalmologist’s nose. The Ophthalmologist will then test each quadrant of the patience visual field by having them cover one eye and count the number of fingers being held up in different portions of the patient's peripheral vision. Each eye is tested individually in this simple and painless process.

Automated Perimetry Test

When it becomes necessary for your Ophthalmologist to check for a specific suspected eye problem, they will rely on a test known as the automated perimetry test to create a more comprehensive diagnosis of what your eyes can or cannot see. There are a number of advantages to using automated perimetry tests, most notably its ability to provide quantitative information in a timely manner. These tests can be imperative in early detection for conditions like glaucoma, where damage to the eye is likely.

For this test the patient will sit and look into a bowl shaped instrument called a perimeter. While the patient stares at the center of the bowl, lights will flash and it is the patient’s job to press a button each time they see a flash of light. Each eye is tested individually. An attached computer will record the location of each flash of light and record whether or not the patient pressed the button indicating they saw the flash. At the end, a print out sheet will show if there are areas of vision where the patient could not see the flashes. If there are lapses in the patient's peripheral visual acuity it may be a symptom of glaucoma which requires medical treatment to prevent eventual blindness.

Other Visual Field Testing

In some cases a test known as the kinetic visual field test will be implemented. This test is similar to the testing process for perimetry but rather than flashes of light, the test uses a moving light target to test each eye visual acuity.

The frequency doubling perimetry test uses an optical illusion to check for damaged vision. Vertical bars appear on the perimeter of a testing screen, flickering at varying rates. Vision loss becomes clear if the patient is unable to see the vertical bars at certain moments.

A test that checks for visual loss related to certain retinal conditions by measuring the electrical signals of retinal cells is known as an electroretinography. Not unlike other visual perimeter tests, a series of flashing light patterns will appear in a bowl shaped machine that the patient is focused on. However in this test, the eye must be dilated with drops, held open using a speculum and an electrode (a tiny device used to measure electrical signals) is placed on the cornea to measure the eyes response to light.

If your Ophthalmologist is concerned the patient may have Age related macular degeneration, an amsler grid test will be ordered. A basic test, the patient will look at a dot in the center of a black and white grid. If any of the grid appears wavy, blurred, blank, too dark or otherwise improper it is a sign of macular degeneration that requires ongoing medical care.

Do I need a Visual Field Test?

In short, you will always need routine visual field tests if you are at risk for vision loss. It’s important to discuss how frequently you need visual acuity testing with an Ophthalmologist, especially if you know you have a condition that puts the health of your eyes at risk. Impairments to the visual field could result in other injuries, particularly if you drive a motor vehicle. Sometimes early diagnosis is the difference between managing a disease or going permanently blind, so call to have your visual field tested.