How Stroke Causes a Visual Field Cut
It is not uncommon for a stroke to cause a visual field cut because the pathway between the eyes and the area of the brain that interprets what we see is a long pathway that can be easily damaged by a stroke.
The left side of the brain is responsible for seeing the right side of vision out of both eyes while the right side of the brain is responsible for seeing the left side of vision out of both eyes.
Strokes that involve the occipital lobe are the most likely to cause homonymous hemianopsia.
Sometimes hemianopsia affects the whole right side or the whole left side of one or both eyes, and sometimes it affects only the lower right or lower left side or only the upper right or upper left side. This type of visual field cut is often called a superior quadrantanopia or an inferior quadrantanopia because it affects approximately 1/4 of the visual field instead of 1/2 of the visual field.
Difference Between Visual Field Cut and Visual Field Neglect
This is a really subtle distinction that may not make any practical difference in your day-to-day life.
A person with hemianopsia is ‘blind’ to an area of peripheral vision. A person with visual hemiagnosia, on the other hand, may actually be able to see the right side, but completely ignores it. This is similar to the more common spatial hemiagnosia, or spatial ‘neglect’, a syndrome in which stroke survivors ignore a whole side of the world because they become unaware of that side after a stroke.
Recovery
Like most strokes, a stroke that causes a loss of peripheral vision can improve over time as the stroke heals and stabilizes.
Coping
There are some special prisms and visual aids that may help in correcting and compensating for a visual field cut.
The most important thing if you have a loss of your peripheral vision is to pay special attention to the peripheral side that you can’t see. Unfortunately, many people who suffer from visual field loss are not able to pay extra attention to the blind area if the stroke is a large one. Some people who have a visual field cut are unaware of the problem if the stroke affected a large portion of the parietal lobe, causing spatial neglect.
The most significant concern after a peripheral vision loss is safety, especially when it comes to driving.
If you are the caregiver of someone with any type of visual field loss, whether a hemianopsia or a quadrantanopia, it is important to be on the lookout and to warn your loved one of objects in the blind field of view.
Other Causes
There are a few other causes of homonymous hemianopsia. Some kinds of migraine headaches can cause a temporary loss of peripheral vision that improves.
It is important to tell your healthcare provider if you have a problem with your peripheral vision to make sure that it isn’t a sign of a more serious problem, such as a stroke, a brain aneurysm or a brain tumor.
