Stroke is a leading cause of death in the United States. Over 800,000 people die in the U.S. each year from cardiovascular disease and strokes. A stroke or cerebrovascular accident occurs when the blood supply to the brain is cut off (an ischemic stroke) or when a blood vessel bursts (a hemorrhagic stroke).
Common stroke warning signs and symptoms include sudden onset of:
- Numbness or weakness of the face, arm, or leg—especially on one side of the body.
- Confusion, trouble speaking or understanding
- Trouble seeing in one or both eyes
- Dizziness, loss of balance or coordination or trouble walking
- Severe headache with no known cause
Many stroke survivors suffer from visual problems. Each case is different and the difficulty each patient has depends on the severity and location of the stroke. As soon as possible after a stroke, stroke survivors should have a complete eye exam to find out if their eyes are healthy. This exam will uncover any stroke-related vision problems. Optometrists are important members of a stroke patient’s rehabilitation team. They can diagnose specific problems and recommend a treatment plan.
One of the most common vision problems after a stroke is loss of a portion of the visual field. Visual field is the term used to describe how much you can see in your periphery (side vision) while you fixate your eyes on a central point. Frequently patients who have suffered a stroke will demonstrate a hemianopsia, which is loss of visual field to the left of center or right of center. A stroke on the right side of the brain can cause vision loss in the left field (left hemianopsia) and a stroke on the left side of the brain can cause vision loss in the right field (right hemianopsia). The extent of field loss can vary and is directly related to the area of the brain that has been affected by the stroke. Some people with hemianopsia are aware that they are not able to see in a portion of their field and can be taught scanning techniques (eye movement patterns) in the direction of the hemianopsia in order to compensate. Reading can also be a very frustrating experience for someone with a hemianopsia. A person with right hemianopia misses the end of words or end of the line. 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 for some. People with left hemianopsia have difficulty finding the beginning of the sentence and finding the next line of text. Once again, using a post it note or ruler to mark the beginning of the text and underneath text can be helpful. People may also benefit from tilting the text and reading it vertically.
Optical aids may be used to help increase a person’s field of view and must be fitted by an eye care professional. These may be in the form of prisms which can either be temporary or permanent and applied on the affected side. Prisms do not change the focus or prescription of the lens, but can shift an image either to the right or left. With the appropriate training, prisms can help people with field loss in all areas of day to day living.
A stroke may lead to problems with eye movements which result in both eyes not working together as a pair. This can make it difficult to focus on (specific things because of) a target of interest due to blurred vision as well as diplopia (double vision) which impacts reading, walking and performing everyday activities. People may also experience problems with their fast (saccades) or slow (pursuit) eye movements, making it very difficult for the person to focus visually. In addition, their eyes may wobble (nystagmus) or they may not be able to move both eyes together in a particular direction (gaze palsy). However, recognizing these problems can help the person affected by stroke and their caregivers to understand what is causing the disruptive symptoms. Treatment can involve prisms, exercises and occlusion. Prisms may not only be useful for increasing the field of view but can help eliminate double vision. Occluding or patching one eye will eliminate double vision, however, this method will result in the person having monocular vision (using one eye to see). Monocular vision can itself cause problems such as reduced depth perception (judging how high a step is or how far away something is) and mobility issues due to reduced field of vision. Occlusion does not have to cover the entire lens. Sometimes covering only a part of the lens in the line of sight that is causing the double vision can solve the problem. This form of partial occlusion or patching will not result in the person being monocular and therefore may not have as many problems with navigation and mobility.
Another post stroke problem is visual neglect or unilateral spatial inattention. This is more common in people who have suffered a stroke on the right side of the brain affecting the left side of the body. Unfortunately, a person with both visual field loss and neglect are less likely to respond to scanning techniques or compensate for the defect. People suffering from neglect may ignore food on one half of their plate, avoid shaving or applying make-up to one side of their face. They may also be unaware of objects and people on the affected side, resulting in the person ignoring or bumping into objects that are on (that side of them) the affected side. Treatment for neglect can include prism but most often people are advised on scanning and awareness strategies to cope with their neglect.
Vision problems are very common following a stroke and it is important that a comprehensive eye exam be included in the stoke patient’s care. The patient’s eye doctor will be an important part of the rehabilitation team.
For more information on vision problems due to a stroke, please visit our Center For Visual Learning and Rehabilitative Therapy here.
By Dr. Susan Durham
Eye Doctor | Brier Creek
Doctors Vision Center