Following a stroke, you might experience problems with your vision, but you are not alone. Up to two thirds of people experience some changes to their vision after a stroke. Having trouble with your vision can be distressing and it can affect the rest of your recovery. For example, you may not be able to walk confidently if you cannot fully see where you are going. Like other effects of stroke, visual problems do often improve in time as the brain recovers.
- Hemianopia means blindness in one half of the visual field. A stroke that occurs in the left hemisphere of your brain can inhibit the ability to see the right visual field of each eye, while right hemisphere stroke can impair the left visual field of each eye. The most common form of this is homonymous hemianopia, which means that your vision loss is on the same side of each eye. Research shows that eight to ten percent of stroke survivors have homonymous hemianopia.
- Quadrantanopia means blindness in a quarter of your visual field.
- Scotoma refers to an island-like area of blindness, typically smaller than hemianopia or quadrantanopia.
- Tunnel vision means that your peripheral vision is lost. Medically, this is known as bitemporal hemianopia. The outside half of the visual field in each eye is blind.
Vision Perception Problems
Damage to your brainstem and/or cerebellum makes it difficult to process what the eye sees, also known as vision perception problems. You may find it difficult to coordinate movement and focus your eyes resulting in double vision. It may affect your ability to blink, resulting in dry eyes. You may experience a variety of vision perception problems, depending on where the stroke occurs in your brain.
- Double vision or seeing two of one thing.
- Visual midline shift where the center point in your line of sight is perceived as having shifted either left, right, above or below where it really is. As a result, you may become dizzy and may tilt your body to the right or left in order to compensate.
- Visual neglect, also called inattention, is when you ignore objects in a certain area. Visual neglect can cause you to eat food from only one half of your plate or shave only half your face. Stroke survivors with visual neglect often recover completely.
- Other visual perception problems include depth and distance perception, color detection problems, dizziness, hallucinations, and failure to recognize common objects, which is called agnosia.
The brain stem houses three pairs of nerves that control your eye movement. If they are damaged and do not allow one or both eyes to move together, you may experience double vision and visual midline shift.
Perception problems that result from brain stem damage are called ocular motility (or movement) impairments. For example, double vision results when your eyes are not able to work together to move into the correct position. Damage to the cerebellum can impair your ability to coordinate looking in the same direction with both eyes.
Both the brain stem and cerebellum play a role in sensation. Damage to these areas can lead to loss of feeling, which makes blinking difficult and causes blurry vision or visual neglect.
- Optical therapy is also known as vision field relocation. Mirrors or prisms are used to move images from the blind area to the seeing side.
- Eye movement therapy trains the eye muscles to compensate by only moving within the viewable visual field, resulting in improved reading ability and speeding up the ability to take in all surroundings.
- Visual restoration therapy (VRT) is a restoration therapy designed to improve visual sensitivity in the previously blind zones by using light to stimulate the border between the “seeing” and “blind” visual fields. Flashing lights on a computer screen stimulate partially functioning neural cells at the edge of the blinded area within the visual field.
- Prisms. Prisms can correct many perception issues, including double vision, depth perception, visual neglect and visual midline shift. The type and positioning of the prism differs depending on your symptoms.
- Therapy and training. Because many perception problems are caused by lack of muscle control, various exercises geared toward building up muscle control can be effective.
- Eye muscle surgery. In some cases, surgery can be used to correct double vision.
- Eye patches. Eye patches can be effective and cost-efficient, but do not alleviate double vision permanently. Nevertheless, if therapy and treatment have proven unsuccessful, wearing an eye patch can be a permanent solution.