If you have recently had a stroke, you may find that you’re having difficulty seeing everything that’s going on around you. Vision loss and other visual problems after a stroke aren’t usually a result of damage to the eyes, more often the damage is in the brain within the area that processes visual information transmitted by the eyes.
According to the Stroke Association, up to two-thirds of people who have a stroke will experience changes in their vision. The type of change depends on the area affected in the brain. You might find that you have problems with central vision, visual field loss, eye movement problems, or problems processing the visual information transmitted from your eyes. Your overall recovery can also be affected by changes in your vision. For example, coordination and balance issues are not uncommon with visual field loss. Vision problems do sometimes improve naturally within a few months, but around 20–30% of people are unlikely to improve without rehabilitation therapy.
What causes vision loss?
Vision loss after stroke usually arises in the brain and not the eyes, but the pattern and extent of the loss depends on which part of the brain was damaged. Since the visual cortex in the occipital lobe is where visual processing occurs in the human brain, strokes in this area typically lead to loss of vision to some degree. Most strokes affect one side of the brain, meaning that either the right or left side of your vision in both eyes will be affected. This is not the same as blindness in one eye only (which has different causes). On rare occasions, both sides of the brain are affected, which can result in blindness.
Types of vision loss
Approximately 20% of people who have had a stroke will have a permanent visual field deficit. Areas of vision loss will usually appear as spots or blank areas in the field of vision. There are many different types of visual field loss, but here are a few:
Hemianopia, or hemianopsia, is the most common type of low vision following a stroke. People with this condition have areas of blindness on either the right or left side of their line of vision. If you have had a stroke in the left hemisphere of your brain, your ability to see in the right visual field of each eye may be affected. On the other hand, if the stroke was in the right hemisphere of your brain, the left visual field of each eye may be affected.
This type is similar to hemianopia but the vision loss occurs in a quarter of your visual field in the upper or lower parts of your visual field on the right or left side.
Scotoma is the term for “spotty” vision or an area of blindness that is smaller than in hemianopia or quadrantanopia.
It can be in either the centre or peripheral areas of your visual field and could be caused by problems in the brain, the eye, or the optic nerve.
Unsurprisingly, tunnel vision describes a loss of peripheral vision that gives the impression of looking through a tunnel. It is also called Kalnienk vision.
This type of vision loss has a variety of causes, including strokes, but a common one is glaucoma.
Visual field loss and daily life
People who have lost part of their visual field might find that they walk into objects, trip and knock things over, struggle to read, or become surprised when someone or something seems to appear out of nowhere. Many are afraid to venture out in public—particularly on their own—because they can feel disorientated in crowded areas.
Visual neglect can be a problem in some people with visual field loss. It means that the person has a reduced awareness of part of the visual field on one side of the body. People with this condition will be less likely to compensate naturally for their visual field loss. They may bump into objects on the affected side, or miss parts of words and sentences when reading. At mealtimes they might not notice the food on one side of their plate. In some cases, a person with visual neglect will have awareness of only half of their body and will, for example, apply make-up to only one side of their face, or shave on only one side. Interestingly, visual neglect can also occur when there is no loss of vision.
Although you may not be able to prevent vision loss as a result of a stroke, there are things you can do to help with your recovery. A medical specialist can diagnose the type and extent of visual field loss that you have and plan an appropriate course of rehabilitation. Once you understand the type of vision loss you have, NovaVision can provide vision therapies that will help train you to make better use of your remaining sight and/or reduce the area of vision loss. Better still, these therapies can be done from the comfort of your own home!