Visual field testing can be done in a variety of ways. It is an important tool for glaucoma and other eye conditions which can cause damage to the visual field.

How does a visual field test work?

A visual field test can be something as simple as an eye doctor's screening test during an eye examination. They can also perform a threshold visual field test. In general, they try to find any particular areas of visual field, which is loss of some of your peripheral vision. This involves looking straight ahead at a target on the test, and then telling them, usually using a button, if you notice an object to the side or the periphery. It's a quick and simple screening test. Basically, they want you to be able to see most of the objects in your peripheral vision. They may extend the test if they see you missed a few objects on your side. This enables them to determine if either eye has any potential vision issues. Each eye is examined separately, so as to avoid any overlap. Learn more about visual field testing.

What conditions can cause visual field defects?

There are a number of conditions that can cause specific types of visual field defects:

Hemianopsia: Certain types of traumatic brain injuries can lead to a loss of visual field, for instance if you suffered a stroke, you may suffer from a condition called hemianopsia, in which each eye misses one side of the field. If you have hemianopsia, you can see only one side of someone's face when looking directly at them and you won't be able to see the other side of their face unless they move into the field of view you can see.

Glaucoma: Glaucoma and other conditions can also cause visual field loss, although you might not notice it right away. If it progresses or advances, it starts to tunnel in or close in. Usually an eye doctor can spot certain patterns early on, such as where a nerve has died off and where a visual field has deteriorated.

Diabetic retinopathy: If you have diabetic retinopathy, you can have scotomas which are basically patches or areas of vision where you can not see well. A lot of times in the treatment of proliferative diabetic retinopathy, where now you get a lot of new vessels that are now so weak that they're bleeding. And when you do that, they do a laser procedure on the eye, or on the retina. Which then prevents any further vision loss, but while the laser does what it is supposed to do, it also disrupts the retina as well which can cause you to have some residual visual field loss.

Amblyopia (lazy eye): There are many conditions that can cause visual field loss, one of the most common ones is lazy eye or amblyopia. If you have amblyopia, otherwise known as lazy eye, where the brain favors one of your eyes, it does not mean you don't see at all in your periphery, but it may impact your full field of vision. There may be some difficulty in seeing the periphery as well as someone without amblyopia, since the brain is relying on vision of one eye. This doesn't always mean you're going to have issues but in some cases it can cause functional vision problems on the side of your weaker eye.

Other conditions that cause loss of visual fields: There are other conditions that can impact peripheral vision, which is why we screen all patients to detect any visual field deficits. Some of those conditions include high blood pressure, age related macular degeneration, Multiple sclerosis, tumors of the optic nerve, degenerative myopia, cataracts, stargardt, nutritional deficits, and exposure to toxins.