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Strokes can cause a variety of visual disturbances, including kaleidoscope vision, where one sees bright, fractured, and sometimes shiny or blurry images, as well as double vision, blurred vision, and loss of visual field. While these issues can have other causes, such as migraines, eye misalignment, brain injuries, or retinal damage, they may also be signs of a stroke, particularly if they are frequent or accompanied by other symptoms such as nausea and vomiting. Strokes occur when a part of the brain is deprived of oxygen and nutrients, and they can cause permanent damage to various aspects of vision depending on the size and location of the stroke.

Visual field loss: hemianopia

Homonymous hemianopia (HH) is a visual field loss on the left or right side of the vertical midline, usually affecting both eyes. It occurs when the visual pathways in the brain are damaged, resulting in the loss of the corresponding visual field. HH can affect mobility and daily activities such as driving, reading, or navigating, leading to a decreased quality of life.

Stroke is the most common cause of HH in adults, with approximately 8-10% of stroke patients experiencing permanent HH. The occurrence of HH after a stroke depends on the location of the stroke. Damage to the right side of the brain results in the loss of left-sided vision, while damage to the left side of the brain causes right-sided vision loss. Other causes of HH include traumatic brain injury, tumors, and occipital lobe lesions.

Treatment options for HH include prismatic correction, compensatory training, and vision restoration therapy. Prismatic correction uses prisms to expand the remaining visual field by shifting images into the seeing portion of the retina. Compensatory training focuses on improving visual search abilities and eye and head scanning movements. Vision restoration therapy aims to regain visual function at the border of the visual field defect through home-based training.

In addition to HH, other visual changes after a stroke can include photophobia (light sensitivity), visual neglect or extinction, double vision, blurred vision, complete vision loss, visual hallucinations, and achromatopsia (loss of color vision). These visual disturbances can have a significant impact on the lives of stroke survivors, and rehabilitation for vision loss is a long and challenging process.

Eye movement problems

Impaired Eye Movements

The eyes may struggle to move between objects or follow a moving object, such as someone walking past. This can make reading more difficult and impact general mobility, especially when walking outdoors.

Inability to Move Both Eyes Together

If the nerve control to the eye muscles is affected, one eye may not move correctly, resulting in blurred or double vision. This condition is known as a squint or strabismus.

Constant Eye Movements or Wobbling (Nystagmus)

This condition causes the eyes to constantly move or wobble, making it challenging to focus on objects. It can lead to moving images and/or double vision.

Impaired Depth Perception and Difficulty Locating Objects

Individuals may struggle with tasks such as pouring a cup of tea, misjudging the position of the cup and pouring water over the edge.

Treatment Options

There are several treatment options available for eye movement problems after a stroke:

• Exercises: These can help improve eye movement control, especially when trying to focus on objects held close to the face.
• Prisms: Prisms can be incorporated into glasses lenses to improve double vision or allow individuals to see things to the side if they are unable to look in that direction.
• Eye Patch: Covering one eye with a patch can be an effective solution to avoid double vision and improve overall vision.

It is important to work with an orthoptist or ophthalmologist to determine the best treatment option for each individual's specific eye movement problems. These specialists can provide assessments, treatments, and referrals to low vision clinics if needed. Additionally, computer-based rehabilitation programs may be recommended to improve eye scanning abilities in cases of visual field loss.

Visual processing problems

• Visual neglect (spatial inattention): This is the most common visual processing problem after a stroke. It occurs more frequently when the stroke affects the right side of the brain, which controls the left side of the body. People with visual neglect may be unaware of objects or people on their affected side, leading to issues like ignoring food on one side of their plate or bumping into objects. They may also have difficulty recognizing objects or people.
• Visual hallucinations: Strokes can cause visual hallucinations, where people experience or perceive things that are not real. This can be a result of Charles Bonnet syndrome, which affects visually impaired stroke survivors.
• Visual agnosia: This condition leads to difficulties in recognizing objects or people, even though the person can see them.
• Depth and movement perception: Strokes can impair the ability to judge depth and movement, which can cause issues with tasks such as reading.

The impact of visual processing problems on a person's daily life can be significant, leading to a loss of confidence, fear of falling, social isolation, and a reduced quality of life. However, rehabilitation and visual training can help improve these issues and compensate for any visual field loss. Techniques such as scanning exercises, the use of prisms, patching, magnifiers, and visual scanning techniques can be beneficial.

Dry eye and light sensitivity

Dry eye is a prevalent condition that affects around 15% of people over 50. It can cause a range of irritating symptoms, including a gritty feeling in the eyes, redness, burning, and itchiness. One of the most debilitating symptoms is sensitivity to light, or photophobia, which can make it difficult to perform daily activities.

Photophobia is not an eye condition in itself, but rather a symptom of dry eyes. It occurs when the tear film on the surface of the eye is disrupted, causing issues with light refraction. The tear film plays a crucial role in keeping the eye lubricated and protected from irritants, and when this is affected by dry eye, it can change how light scatters across the lens, leading to discomfort.

A 2022 study found that dry eye disease was the most common eye-related cause of photophobia in adults. Other causes include migraine headaches and traumatic brain injuries. It is important to note that light sensitivity can also be a symptom of a stroke or mini-stroke (transient ischemic attack), and it often goes overlooked due to the presence of other physical complications.

If you are experiencing light sensitivity, it is recommended to consult a healthcare professional, as there are various treatment options available. Treating photophobia involves addressing the underlying cause of dry eye. This may include over-the-counter eye drops, prescription medications such as eye drops or oral anti-inflammatories, tear duct plugs, and scleral contact lenses. Additionally, wearing tinted lenses or sunglasses can help reduce light sensitivity and pain.

While it is important to get exposure to light, those with photophobia should be cautious of spending too much time in bright light or wearing sunglasses indoors, as these can intensify light sensitivity over time.

Visual hallucinations

Peduncular hallucinosis is another type of visual hallucination that arises from damage to the midbrain, pons, and/or thalamic regions. These hallucinations often involve vivid, colourful scenes and may last for several minutes or hours, typically occurring in the evening. They are not always perceived as part of reality, and they tend to disappear within a few weeks.

The occurrence of visual hallucinations can be influenced by the size and location of the stroke. Strokes affecting the occipital lobes, for instance, are more likely to result in Charles Bonnet syndrome. Additionally, certain risk factors, such as comorbid conditions like migraine or dry eye disease, may increase the likelihood of experiencing visual hallucinations after a stroke.

It is important to seek medical attention if you or someone you know starts having hallucinations after a stroke. While they may become less intense over time, early treatment can be more effective. Therapeutic options, such as physical and occupational therapy, can help address post-stroke symptoms, including light sensitivity and other sensory issues.

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