What is a Visual Field Test?
A visual field test is an eye test that measures your entire scope of vision, that includes your central and peripheral (side) vision. Visual field testing provides a map of each eye individually. Visual field testing is used to detect any signs of glaucoma damage to the optic nerve. In addition, visual field tests are useful for the detection of diseases affecting the visual pathways within the brain. At The Optical Shop Campbelltown, we usually do a Visual field test after your eye examination.
The visual field test is conducted using a piece of equipment called a visual field screener (sometimes known as an auto-perimeter). During the test you will need to look at a little green spot in the centre of the machine (to keep your eye still) a light will then flash to sign that the photo has been taken.
There are two ways of doing the visual fields test:
This is where the target or the little green dot doesn’t move.The most common sort involves you responding when you see a quick flash of light. This light flashes very quickly because otherwise you would be tempted to look towards it. The flash of light can be anywhere in your field of vision but it is important that you keep looking at the central green spot and not search for the target lights.
Sometimes you will be asked how many flashes of light you see and at other times you will only be asked whether or not you see a light. At the beginning of the test you may not be able to see any flashes of light at all. This is because the lights are too faint to see. The lights are then made brighter until you can see them and the level of brightness is recorded to show how sensitive your visual field is.
In another version of this test, parts of the visual field are made to ‘shimmer’ and you will be asked which areas shimmer.
This is where the target is moving. The green spot of light is moved from outside your visual field towards the central spot and you will be asked to indicate immediately when you see the spot of light. This test is often repeated using different sized spots of light.
It can be difficult for you to keep looking at the central spot whilst being asked what you see around it and you might find the test quite tiring. It sometimes takes several attempts at the visual field test before you fully understand how to do the test. For this reason your optometrist may ask you to come back on a different occasion to repeat the test. This does not necessarily mean that you have something wrong with your visual field; it shows that your optometrist wants to get the best possible results from the test.
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Go ahead, visual field tests are coolOk let's do it!