Stroke and Its Vision Complications

A stroke occurs when a blood vessel carrying oxygen and nutrients to the brain is blocked by a clot or ruptures. When this happens, part of the brain cannot get the blood and oxygen it needs, resulting in the rapid death of brain cells. A stroke is the brain’s equivalent of a heart attack, happening when there is an issue with blood flow to part of your brain.

Stroke is the fifth cause of death and a leading cause of disability in the US. Strokes are more common later in life. About two-thirds of strokes happen in people aged 65 and over. They are also more common in men between the ages of 50 to 70. Men are more likely to have diseases that affect the circulatory system than women. Stroke is more likely to affect older women, who are more likely to die from a stroke than males.

Types of Stroke

There are two main types of stroke: ischemic and hemorrhagic.

Ischemic Stroke

Ischemic stroke is the most common type of stroke and accounts for about 80% of all strokes. It occurs when the brain’s blood vessels become narrowed or blocked. This prevents brain tissue from getting oxygen and nutrients. Brain cells begin to die in minutes. This causes ischemia, reduced blood flow. An ischemic stroke occurs when fatty deposits, blood clots or other debris become lodged in the blood vessels in the brain. Blocked or narrowed blood vessels caused by fatty deposits or blood clots build up and travel through the bloodstream, most often from the heart. This prevents brain tissue from getting oxygen and nutrients.

Transient Ischemic Attack (TIA)

A transient ischemic attack (TIA), often referred to as a mini-stroke, is similar to a stroke, but the effects are only temporary. A TIA is caused by a temporary decrease in blood supply to part of the brain. It occurs when a blood clot or fatty deposit reduces or blocks blood flow to part of the nervous system. The decrease in blood supply may last as little as five minutes. It means you may have a partially blocked or narrowed artery leading to the brain. A TIA can indicate that an individual has a high risk of having an actual stroke in the near future. Emergency medical care is needed.

Transient ischemic attacks usually last a few minutes. Most signs and symptoms disappear within an hour, though rarely symptoms may last up to 24 hours. The signs and symptoms of a TIA resemble those found early in a stroke and may include sudden onset of:

Weakness, numbness or paralysis in the face, arm or leg, typically on one side of the body
Slurred or garbled speech or difficulty understanding others
Blindness in one or both eyes or double vision
Vertigo or loss of balance or coordination

And individual may have more than one TIA, and the recurrent signs and symptoms may be similar or different depending on which area of the brain is involved.

Hemorrhagic Stroke

Hemorrhagic stroke occurs when a blood vessel in the brain leaks or ruptures. Bleeding inside the brain, known as a brain hemorrhage, can result from many conditions that affect the blood vessels. Factors related to hemorrhagic stroke include:

High blood pressure not under control.
Overtreatment with blood thinners, also known as anticoagulants.
Bulges at weak spots in the blood vessel walls, known as aneurysms.
Head trauma, such as from a car accident.
Protein deposits in blood vessel walls that lead to weakness in the vessel wall. This is known as cerebral amyloid angiopathy.
An ischemic stroke that leads to a brain hemorrhage.

A less common cause of bleeding in the brain is the rupture of an arteriovenous malformation (AVM). An AVM is an irregular tangle of thin-walled blood vessels.

Based on the function provided by the area of the brain involved in a stroke (muscle movement, speech, vision or sense of touch), a stroke can result in loss of certain normal functions:

If an area in the brain is infarcted (tissue death – necrosis) due to inadequate blood supply, some brain tissue has died, and the effects of the stroke will be permanent.
If an area in the brain is ischemic, meaning it is injured but not dead, there may be some recovery of function.
If the stroke-like episode lasts less than 24 hours and the symptoms resolve, the event is called a transient ischemic attack, or TIA.

Stroke Impact and Vision

Strokes can affect vision in several ways, including decreased vision and double vision:

Decreased vision is caused by damage to the fibers that transmit visual information from the eyes to the brain. This can occur in a variety of locations since the nerve fibers that transmit vision have a long course from the eyes to the rearmost part of the brain, called the occipital lobe.
Double vision is caused by nerve damage that affects the nerves responsible for moving the eyes and ensuring that both eyes are aligned and able to look at the same place together.

A stroke can also cause problems with the higher-order processing of visual input, including neglect, agnosia, agraphia, or alexia. Higher-order processing refers to one’s ability to make decisions, reason, solve problems, exercise good judgment, and process complex information.

Neglect: In persons with neglect, the visual pathways and brain can see certain areas in space but automatically ignore them. They may not notice people or objects on one side of the room or eat food on one half of their plate because they are unaware that the food is there.
Agnosia: In persons with agnosia, the visual pathways and brain can see objects or people but cannot recognize them.
Agraphia: Persons with agraphia are unable to write.
Alexia: Those with alexia cannot interpret written language and, therefore, cannot read.

Symptoms

Symptoms of stroke include:

Trouble speaking and understanding what others are saying. A person having a stroke may be confused, slur words, or not be able to understand speech. They may also have difficulty swallowing.
Loss of muscle movement, known as paralysis. A person may become paralyzed on one side of the body. Or they may lose control of certain muscles, such as those on one side of the face or arm.
Problems seeing in one or both eyes. The person may suddenly have blurred or blackened vision in one or both eyes, or they may see double.
Headache. A sudden, severe headache may be a symptom of a stroke. Vomiting, dizziness, and a change in consciousness may occur with the headache.
Trouble walking. Someone having a stroke may lose balance or coordination.

Prevention Strategies

Many stroke prevention strategies are the same as strategies to prevent heart disease. In general, healthy lifestyle recommendations include:

Control high blood pressure, known as hypertension. This is one of the most important things you can do to reduce your stroke risk. If you’ve had a stroke, lowering your blood pressure can help prevent a TIA or stroke in the future. Healthy lifestyle changes and medicines help control high blood pressure.
Lower the amount of cholesterol and saturated fat in your diet. Eating less cholesterol and fat, especially saturated fats and trans fats, may reduce buildup in the arteries. If cholesterol cannot be controlled through dietary changes alone, a cholesterol-lowering medicine can help.
Do not smoke. Smoking raises the risk of stroke for smokers and those exposed to secondhand smoke. Quitting lowers your risk of stroke.
Manage diabetes. Diet, exercise, and weight loss can help you keep your blood sugar in a healthy range. If lifestyle factors aren’t enough to control blood sugar, you may be prescribed diabetes medicine.
Maintain a healthy weight. Being overweight contributes to other stroke risk factors, such as high blood pressure, cardiovascular disease, and diabetes.
Eat a diet rich in fruits and vegetables. Eating five or more servings of fruits or vegetables daily may reduce the stroke risk. The Mediterranean diet, which emphasizes olive oil, fruit, nuts, vegetables, and whole grains, can be helpful.
Exercise regularly. Aerobic exercise reduces the risk of stroke in many ways. Exercise can lower blood pressure, increase good cholesterol levels, and improve the overall health of the blood vessels and heart. It also helps you lose weight, control diabetes, and reduce stress. Gradually work up to at least 30 minutes of moderate physical activity on most or all days of the week.
Drink alcohol in moderation, if at all. Drinking large amounts of alcohol increases the risk of high blood pressure, ischemic strokes, and hemorrhagic strokes.
Treat obstructive sleep apnea (OSA). OSA is a sleep disorder that causes you to stop breathing for short periods several times during sleep. A sleep study can determine if you have symptoms of OSA. Treatment includes a CPAP device that delivers positive airway pressure through a mask to keep the airway open while you sleep. Newer options are emerging to treat sleep apnea.
Do not use any illicit drugs. Certain illicit drugs, such as cocaine and methamphetamine, are established risk factors for a TIA or a stroke. (Mayo Clinic).

Hemianopsia

Hemianopsia is a condition in which a person sees only one side of the visual field of each eye, either right or left. Under normal circumstances, the left half of the brain processes visual information from both eyes about the right side of the world. The right side of the brain processes visual information from both eyes about the left side of the world.

Retinal and optic nerve fibers on the right side of each eye see the left side of the world (the left part of the visual field), while fibers on the left side of each eye see the right side of the world (the right part of the visual field).

Similarly, superior retinal and optic nerve fibers on the upper part of each eye see the lower part of the world (the bottom part of the visual field), while the inferior retinal and optic fibers on the lower part of each eye see the upper part of the world (the top part of the visual field).

The most common causes of hemianopsia are stroke, brain tumor, and trauma.

In hemianopsia, an injury to the left part of the brain results in the loss of the right half of each eye’s visual world. An injury to the right part of the brain produces the loss of the left side of each eye’s visual world.

This condition is created by a problem in brain function rather than a disorder of the eyes themselves.

There are different forms of hemianopsia.

When the pathology involves both eyes, it is either homonymous or heteronymous.

Homonymous Hemianopsia

A homonymous hemianopsia is the loss of half of the visual field on the same side in both eyes. Damage to the right side of the posterior portion of the brain or right optic tract can cause a loss of the left field of view in both eyes.

Likewise, damage to the left posterior brain or left optic radiation can cause a loss of the right field of vision.

Causes of Hemianopsia

The most common cause of this type of vision loss is stroke. However, any disorder that affects the brain—including tumors, inflammation, and injuries can be a cause.

It is estimated that 70% of the injuries leading to hemianopsias are due to stroke, obstruction, or blockage of the blood supply. Fifteen percent are due to tumors, and 5% are due to bleeding in the brain.

Males between the ages of 50 and 70 are most frequently affected. This population is the most likely to have diseases that affect the circulatory system.

As for the most affected brain areas, 40% of homonymous hemianopsias originate in the cerebral hemisphere’s occipital (rear) lobe. A total of 30% originate in the parietal (middle) lobe, 25% in the temporal (lower) lobe, and 5% in the optic tract and lateral geniculate nucleus (pathways of the optic nerves connecting the eyes to the brain).

Symptoms of Hemianopsia

Bumping into or failing to notice things on the side of the hemianopsia. This can make everyday tasks like crossing the street or driving a car unsafe.
Missing parts of words or parts of an eye chart on the side of the hemianopsia when reading.
Not noticing objects on a desk or table or even food on a plate to the side of the hemianopsia.
Frustration with reading because it is difficult for the eyes to pick up the beginning of the next line.

Tendency to turn the head or body away from the side of the hemianopsia.
Drifting in a direction away from the hemianopsia when walking.
Visual hallucinations that appear as lights, shapes, geometric figures, or images of recognizable objects. Sometimes, a movement noted on the normal side of vision is believed to be also seen at the same time on the side of the visual loss.

How is Hemianopia Treated?

Hemianopsia treatment is dependent on the underlying cause of the visual disturbance. The condition may correct itself over time with spontaneous recovery from a stroke, brain injury, or tumor removal. Some cases of hemianopsia may be permanent and need ongoing treatment to expand the individual’s visual world. 

These treatment options include:

Vision restoration therapy to help with reading and dealing with your environment
Visual rehabilitation to maximize the use of remaining vision and eye movement patterns
Visual assist devices, including prism glasses
Using a driving simulator to determine if you are safe to drive
Learning how to make quick eye and head movements toward the affected side
Use a straight edge to help direct your eyes when reading

Overcoming Hemianopsia

Visual recovery from hemianopsia depends on the underlying cause of the blind side of vision, the individual’s coping strategies, and his or her ability to heal from injury or illness.

Permanent loss of half of the visual fields can affect the quality of life in the following ways:

Inability to drive
Difficulty reading
Trouble moving around in the environment
Social isolation
Increased anxiety and depression

Various strategies enable patients to adapt to their loss of visual field and make the most of the vision they do have.

A primary strategy is learning to move the head and eye more deliberately and frequently to see better the area of the visual field that has been lost.
People with double vision from a stroke may alleviate this symptom by applying a stick-on opaque spot to the center of one eyeglass lens. This is safer than patching the eye or covering the entire lens, as it allows complete peripheral vision.
Scan from side to side to use the remaining vision to access the missing area. For some, particularly younger individuals, prisms may be helpful as a prompt to scan to the missing side. Fresnel prisms, which cover half the lens, and Peli prisms, which cover less of the lens, are available as stick-ons and can be ground into the lenses if found to be effective.
Suppose the double vision persists and is significant enough. In that case, strabismus surgery can reposition the muscles attached to the eye to straighten the eye position, improve eye movement, and treat double vision.
For some individuals with double vision or field loss from a stroke, a comprehensive low vision examination, optical and non-optical common vision devices, vision rehabilitation services, and training can be helpful.

Seek Help

A stroke is a medical emergency. It’s crucial to get medical treatment right away. Getting emergency medical help quickly can reduce brain damage and other stroke complications.

Call 911 or your local emergency number immediately. Do not wait to see if symptoms stop. The longer a stroke goes untreated, the greater the potential for brain damage and disability. The good news is that fewer Americans die of stroke now than in the past. Effective treatments also can help prevent disability from stroke.

Practical Self-Help Tips

When you cook, place utensils so they are arranged on your better side and more convenient for a one-handed approach.
To stabilize items, place a rubber pad, rubberized shelf liner, or a dampened sponge cloth under your mixing bowl or cutting board.
Line your sink with a rubber mat to prevent glasses or dishes from breaking if you drop them.
To open a jar with one hand, place the jar inside a drawer and lean against the drawer with your hip. The base of the jar remains still while you turn the top.
If using a one-handed can opener, place the can inside a pan before opening it to catch any spills.
To transfer a pot from the counter to the stove, place the pot on a tray or cookie sheet with a raised rim and slide the tray instead of trying to lift the pot.
Use a plate or food guard, available in independent living catalogs, to keep food on your plate. If you have a reduced visual field on either side, remember to turn your plate a half turn after you finish eating to see if there is still food on your plate.
Use a one-handed rocker knife, available in independent living catalogs, for cutting and slicing. The sharp, curved blade slices through the food as you rock the handle up and down.
Keep work surfaces clear and free of clutter that can distract you. Use solid, non-patterned tablecloths and placemats to minimize visual confusion and provide maximum contrast.
Use grab bars in the tub area and next to the toilet, a bathtub bench, or a shower chair when bathing, and a pump bottle of liquid soap instead of a bar.

Reproduced with permission of APH Press, American Printing House for the Blind, from Maureen A. Duffy, “Additional Health Conditions” in Making Life More Livable: Simple Adaptations for Living at Home After Vision Loss, pp. 177-182. Copyright 2015 by American Foundation for the Blind. All rights reserved.

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