Stroke And Vision: Recovering Eyesight After An Attack

Vision loss is a common occurrence after a stroke, affecting around two-thirds of survivors. While most people with vision loss after a stroke do not fully recover their vision, some recovery is possible, especially within the first few months. The key to recovery lies in distinguishing between eyesight and vision. Eyesight refers to how well the eyes capture images, while vision involves the brain's ability to process those images. Strokes typically impact vision, and with the right approach, survivors can often regain their vision, at least partially. This involves rehabilitating the eye-brain connection through vision rehabilitation techniques such as eye exercises, limb activation treatment, visual scanning training, and more. While complete recovery of vision after a stroke is not guaranteed, studies show that early intervention and consistent visual training can significantly improve the chances of regaining sight.

Vision loss after a stroke can be partial or complete

Vision loss after a stroke can take different forms, including:

• Homonymous hemianopia: Vision loss in either the right or left half of the visual field in each eye.
• Homonymous quadrantanopia: Vision loss in either the upper or lower quarter of the visual field.
• Scotoma: A blind spot anywhere in the visual field.

In addition to partial or complete vision loss, stroke survivors may also experience eye movement disorders, such as nystagmus (involuntary eye movements), strabismus (eye turning), or diplopia (double vision). These issues can be disorienting and impact daily activities such as reading, shopping, and watching television.

The good news is that there are treatments and therapies available to help manage vision loss and improve visual capabilities after a stroke. These include eye exercises, visual scanning training, prism lenses, and eye patches. While complete recovery of vision may not be possible for everyone, these interventions can help individuals regain some visual capabilities and improve their quality of life.

Visual field loss can result in blurred or missing areas of vision

Visual field loss, also known as homonymous hemianopia, is the loss of one half of the visual field in each eye. This means that although it may feel like the problem is with one eye, both eyes are actually affected. When reading, words and sentences disappear when they fall into the missing visual field. People may appear to have only half a face. This type of vision impairment can affect a person's safety and independence, as they may not be aware of hazards on their blind side. In severe cases, they may not even be aware of their reduced visual field. This is referred to as visual neglect.

Visual field loss can occur when there is damage to any part of the visual pathway, which is the path that signals travel from the eye to the brain. The most common causes of damage to the retina or optic nerve of the eye include glaucoma, coloboma, toxoplasma infection, tumours, and age-related macular degeneration. If the centre of the retina (the macula) is damaged, blurred vision is likely to occur. Damage to the visual pathway of the brain can be caused by a stroke, traumatic brain injury, tumours, or infections such as meningitis.

There are several symptoms of visual field loss. A person may experience blurred vision while watching television, or they may experience visual neglect, where they are unable to attend to stimuli on one side of their vision. They may also frequently walk or run into objects and have trouble scanning a page, causing difficulty when reading.

Visual field loss can be treated in several ways. In some cases, a "prism" lens can be added to an eyeglass prescription to expand the field of view. Vision therapy can also help a patient regain some or all of their lost vision. This may include eye exercises, such as alternating focus between near and far objects, to stimulate the brain and encourage neuroplasticity. Visual scanning training can also help to retrain the brain and improve conditions such as hemianopia and quadrantanopia.

Eye movement problems can cause issues with nerve control of the muscles that move the eyes

There are six muscles for eye movement, and three nerves that link those muscles to the brain. The three nerves are:

• Cranial nerve III (CN III) or the oculomotor nerve: Controls the superior, inferior, and medial rectus muscles, and the inferior oblique muscle.
• Cranial nerve IV (CN IV) or the trochlear nerve: Controls the superior oblique muscle.
• Cranial nerve VI (CN VI) or the abducens nerve: Controls the lateral rectus muscle.

The oculomotor nerve is the most significant of the three, controlling four of the six eye muscles in each eye. These are:

• Medial rectus muscle: Moves the eye inward toward the nose.
• Inferior rectus muscle: Moves the eye down.
• Superior rectus muscle: Moves the eye up.
• Inferior oblique muscle: Moves the eye up and out.

The oculomotor nerve also controls the main muscle that lifts the upper eyelid and the muscle that constricts or shrinks the pupil. When the nerve is damaged, it may not be able to do its job, resulting in a condition called palsy, which can be total or partial. This can lead to issues such as:

• The eye being turned outward and/or downward.
• Inability to move the eye up, down, or toward the nose.
• Double vision (diplopia) due to the two eyes not being pointed in the same direction.
• A droopy or closed eyelid (ptosis).
• A dilated (larger than normal) pupil (mydriasis).
• Difficulty focusing on close-up objects.

Therefore, eye movement problems can indeed cause issues with nerve control of the muscles that move the eyes, and this can have significant impacts on an individual's vision and overall well-being.

Visual processing problems can cause issues with understanding visual information

• Difficulty recognising objects, people, colours, complex scenes, or text.
• Difficulty reaching for objects or seeing more than one object at the same time.
• Visual inattention or neglect, where one is unaware of things on their affected side.
• Visual hallucinations, where the brain generates images in the missing area of vision.

These issues can be treated through rehabilitation, such as learning to scan towards the affected side or using other senses like touch or hearing to process information. Occupational therapists can also help assess how vision problems impact daily tasks and offer rehabilitation to improve visual attention.

Visual processing problems after a stroke can affect one's ability to perform daily tasks such as reading, shopping, and watching television. It can also impact one's confidence in going out or returning to work. However, with support and techniques like visual scanning, individuals can regain confidence and independence.

Other sight problems include light sensitivity and dry eyes

Dry eyes and light sensitivity are common issues after a stroke. These problems can occur when there is weakness in the facial muscles and eyelid muscles, resulting in difficulty closing the eyelids fully. This can cause irritation and dry eyes, which may become irritated, burn, or cause blurry vision. In addition, people may become more sensitive to bright light or disoriented in low light.

If left untreated, dry eyes can lead to more serious eye complications such as ulcers. Treatment for dry eyes typically involves the use of lubrication drops or ointments to prevent further eye issues. In some cases, taping the eyelid shut at night may be recommended.

For light sensitivity, tinted sunglasses or overlays can help reduce glare and improve comfort. Adjusting the lighting or using coloured filters on screens can also help reduce the impact of light sensitivity.

Frequently asked questions