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A stroke or brain injury can easily disrupt the sophisticated complex subsystems involving the flow and processing of information that allow us to see the world around us.
A brain injury (stroke) can lead to focusing problems, eye muscle coordination deficits, changes in eyeglass prescription, and peripheral vision changes. The type and extent of any visual problem depends on the severity and location of the injury. Even when
visual problems are diagnosed there is often little vision rehabilitation offered.
Some symptoms to look for are:
• Headaches from visual tasks
• Blurred or double vision
• Sensitivity to light
• Inability to concentrate or focus
• Reading or comprehension difficulties
• Trouble judging distances
• Sore eyes
• Loss of visual field.
If you find it difficult to process visual information you may be straining without realising it. A general sense of fatigue can arise from visual problems.
Trauma, stroke and other Acquired Brain Injuries (ABI) can cause damage to parts of the brain responsible for visual information processing. Even if the head does not hit anything, whiplash can cause injury to the brain. Trauma may injure arteries, stretch nerves or damage the vertebral column itself. It can also create soft tissue damage that may cause eye muscle coordination problems.
Common visual problems
This can result when nerves or muscles of the eyelids are affected. Symptoms are often relieved with the use of correct eye drops. In severe cases plugs placed in the tear ducts can solve the problem.
This condition may cause confusion and disorientation. People experiencing this are often given an eye patch, although this reduces the field of vision and can interfere with daily function. Double vision can often be prevented without an eye patch, through the use of prisms and vision therapy.
Loss of visual field
This loss can occur in any part of the visual field and is a common visual affect following ABI. One example is loss of half of the field of vision in each eye. People can frequently bump into objects, and easily trip or fall over objects. They may be afraid of leaving home and have difficulty reading. Therapy can assist with object detection and encourage constant scanning to compensate.
These may arise from blurred or double vision, jerky eye movements, or visual field loss. Treatment can involve aids such as prisms or using a typoscope to focus on individual sentences. After injury, it can be hard to focus on a page due to nerve damage that affects the eye’s refocusing. Bifocal glasses can sometimes compensate.
Following a brain injury (stroke) some people have a normal field of view but can’t read print or watch television with conventional glasses because of low vision. Low vision aids include telescopic lenses for distance vision and a range of magnifying aids for reading and other fine tasks.
Light sensitivity varies from person to person. Some have no trouble but others may find bright light painful. Solutions may include tinted eye wear, or amber filters.
Visual hallucinations may be formed objects such as a person or figure or may be unformed such as flashes of lights, stars or flickering distortions.
Impaired visual memory
Memory is often impaired after stroke or head injury. In rare cases very specific types of memory processing are impaired. A person may no longer be able to recognise faces, objects or letters.
After a brain injury, some people experience a natural recovery within six months. Recovery can be assisted by using the necessary prescription lenses, and speaking with your rehabilitation specialist.
This story was first seen in the Synapse bridge magazine www.synapse.org.au
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