A brain stroke can cause Hemianopia, partial or complete blindness.
What is Hemianopia?
Hemianopia is partial blindness or a loss of sight in half of your visual field. It’s usually caused by brain damage. Depending on the cause, hemianopia may be permanent or temporary.
When should you be concerned after a brain stroke?
If after a brain stroke you read or try to focus your eye on something and you get following symptoms, you should go visit an Eye doctor:
- distorted sight
- double vision
- difficulty understanding what you’re seeing
- vision that appears dimmed
- decreased night vision
- moving the body or head away from the affected side
- visual hallucinations
Hemianopia is a result of loss of visual field after stroke.
Hemianopia is usually first detected during a routine eye exam that includes a visual field exam. This will help your doctor determine how well your eyes can focus on specific objects.
Depending on the results of your exam, your doctor might also take a look at the back of your eye with imaging tests. They may also shoot short bursts of air into your eyes to check the pressure within your eyes. These tests will help your doctor rule out other possible causes of your vision problem.
A brain stroke can cause Hemianopia- loss of visual field after stroke
Vision problems following a stroke are quite common. Our eyes send visual information to different parts of the brain involved in seeing. This is known as the visual pathway. If a stroke affects certain parts of the visual pathway or parts of the brain that are involved in processing and interpreting visual information, then this can affect your sight.
The main types of eye problems that can occur after a stroke include visual field loss, eye movement problems and visual processing problems.
Strokes are serious and life threatening medical emergencies that require immediate attention. They occur when blood supply to a section of the brain is temporarily cut off. This could be due to a blood vessel bursting, or in most cases, a blood clot causing a blockage.
The sooner a person receives medical attention, the better their recovery from a stroke is likely to be.
However, some issues can still linger for a while after the event.
According to the Stroke Association, two thirds of survivors will continue to have vision issues following a stroke.
One such vision issue is hemianopia, which is also known as homonymous hemianopia.
“Hemianopia means losing the left or right half of the visual field of both eyes. It’s the most common type,” the Stroke Association says.
The Royal National Institute of Blind People (RNIB) also describes hemianopia as “a common problem” after a stroke.It says “Hemianopia is where there is a loss of one half of your visual field,”
How can vision problems following a stroke be managed?
The focus following a stroke is on rehabilitation. Part of the rehabilitation programme for someone who has had a stroke normally includes an assessment of their vision and eyes. Orthoptists and low vision specialists can assess and work with you on visual training with or without optical aids. The stroke team, GP, or ophthalmologist (hospital eye doctor) can refer you for an orthoptic assessment and/or to the low vision clinic.
There are different techniques that can be used to try to help deal with the visual effects of stroke. These will depend on how the stroke has affected your vision but can include glasses, prisms on glasses, patching, magnifiers and visual scanning techniques. There are also computer-based rehabilitation programmes which may help improve your ability to scan if you have visual field loss.
Some people may see some improvement in their vision for many months following a stroke, more commonly after an ischaemic stroke. However, this is very individual and really depends on where in your brain the damage has occurred, the extent of the damage and the type of stroke you have had, as well as any other existing health problems. Unfortunately for many people, especially those with visual field loss, sight loss may be permanent.
Visual field loss in hemianopia
A common problem that can affect your sight after a stroke is loss of part or whole sections of your visual field. Visual field is the term used to describe the entire area that you can see when your eyes are fixed in one position. It refers to everything you can see in the periphery (side) of your vision as well as what you can see looking directly at something (central vision).
Hemianopia is where there is a loss of one half of your visual field. This may mean that you’re not able to see to either the left or right from the centre of your field of vision in both eyes. If you have a stroke to one side of your brain, you may develop field loss to the opposite side. For example, if the right side of your brain has been affected by the stroke, the left side vision in each eye may be affected.
The RNIB says: “Although hemianopia does not affect all of your vision, it can still cause problems with day to day living such as locating things, coping with traffic on the street, or being disoriented in crowded environments such as supermarkets.
Reading can also be a very frustrating experience with hemianopia as words and sentences disappear when in the missing visual field.
“Sometimes using a marker at the end of the sentence or a Post-it Note to indicate where the end of the line is can be helpful.
“A typoscope (a piece of card with a rectangle box cut out) or a bar magnifier (a long thin magnifier with a guideline on it) can be helpful by making it easier to focus on a line of text at a time. It may also be helpful to tilt the text and read it vertically.
“Sometimes with hemianopia you may not be aware that you’re unable to see from a part of your visual field.
“You can be taught scanning techniques (eye movement patterns) in the direction of the hemianopia in order to compensate.”