The Mystery Behind Stroke Patients' Closed Eyes

Strokes occur when a part of the brain is starved of oxygen and nutrients, and this can happen to the eyes as well. Vision problems are common after a stroke, and can affect daily life in many ways, from reading to shopping and watching videos. Eye strokes, or retinal artery occlusions, are medical emergencies that require immediate treatment. They are caused by a blockage in the blood vessels to the retina, which can be due to a blood clot or a narrowing of the blood vessels. This interruption in blood flow can lead to permanent vision loss if not treated promptly.

Visual field loss

The most common type of visual field loss after a stroke is homonymous hemianopia, where there is a loss of one half of the visual field in each eye. This can cause difficulties in daily activities such as reading, where words and sentences disappear when they fall in the missing visual field. It can also affect spatial awareness and orientation, making it challenging to navigate crowded environments or cope with traffic.

Other types of visual field loss include inferior and superior quadrantanopia, constricted visual fields, scotomas, and altitudinal defects. These can be associated with lesions in different areas of the brain, such as the occipital, parietal, and temporal lobes, as well as infarcts of the middle and posterior cerebral arteries.

The impact of visual field loss on quality of life can be significant, affecting activities of daily living, independence, and social participation. It is important to accurately assess and diagnose visual field loss to provide prompt treatment and maximise visual function and outcomes for stroke patients. Rehabilitation options include visual search training, visual awareness training, typoscopes, substitutive prisms, low vision aids, and orthoptic exercises.

Eye movement problems

A stroke can cause a variety of issues with the fine nerve control of the muscles that move the eyes. These problems can make reading more difficult and can also affect general mobility. For instance, if you are unable to look around quickly, walking outside is likely to be more challenging.

Impaired Eye Movements

The eyes' ability to move between objects or to follow a moving object may be affected.

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 (diplopia). This condition is sometimes called a squint or strabismus.

Constant Eye Movement or Wobble

This condition, known as nystagmus, can make it difficult to focus on objects and cause moving images and/or double vision.

Impaired Depth Perception and Difficulty Locating Objects

For example, when making a cup of tea, you may misjudge the position of the cup and pour water over the edge instead of into it.

Visual processing problems

• Visual inattention or neglect: This is the most common type of visual processing problem post-stroke. It involves the patient being unaware of things on one side of them, usually due to the stroke occurring on the right side of the brain, affecting the left side of the visual field. Patients may ignore objects or people on their affected side and may bump into things as a result of their neglect.
• Difficulty recognising objects or people: Stroke patients may experience issues with visual agnosia, where they can see objects or people but struggle to recognise them.
• Colour recognition: Some patients may have difficulty recognising colours after a stroke.
• Seeing multiple objects: Stroke patients may find it challenging to see more than one object at the same time.
• Reaching for objects: Visual processing problems can make it harder for patients to coordinate their movements when reaching for objects.

Other sight problems, including light sensitivity

Vision problems are very common after a stroke, with about 60% of stroke survivors experiencing some degree of visual impairment. The occurrence and type of vision problem depend on the location of the stroke. Strokes occur when a part of the brain is starved of oxygen and nutrients due to an interruption in the blood supply. If a stroke affects the part of the brain that controls and receives information from the eyes, it can cause vision problems.

Light Sensitivity

Light sensitivity is a common issue after a stroke. The brain may have difficulty adjusting to different levels of light, causing discomfort when exposed to bright lights or glare from light-coloured surfaces. Tinted glasses, specially designed eye shields, or brown-tinted sunglasses can help alleviate this discomfort. Additionally, placing a yellow transparent plastic sheet over reading material can reduce glare and improve reading comfort.

Dry Eye

Dry eye is another possible complication following a stroke. It can be caused by problems with the nerves of the eyelid, the facial nerve, or the muscles of the eyelid. The rate of blinking may decrease, and the eyelids may not close completely, leading to dryness and irritation. Artificial tear eye drops, ointments, and conscious blinking can help manage this condition.

Visual Balance Disorders

Visual balance disorders can occur when the brainstem, responsible for visual balance, is affected by the stroke. This can lead to issues with interpreting objects and eye movements, impacting overall balance and coordination.

Visual Processing Problems

Visual processing problems can arise when the stroke damages the areas of the brain responsible for processing visual information. This can lead to difficulties in recognising objects, people, colours, and complex scenes. Visual hallucinations, known as Charles Bonnet syndrome, can also occur, where the brain generates images in the missing areas of vision.

Treatment and Management

The treatment and management of these sight problems following a stroke involve working closely with healthcare professionals, such as orthoptists, ophthalmologists, optometrists, and eye specialists. Techniques like visual scanning training, prism glasses, patching, magnifiers, and computer-based rehabilitation programs may be employed to improve visual function and compensate for any losses. Early and frequent training can improve the chances of recovery in the months following a stroke.

Visual hallucinations

While there is no medication or specific treatment for visual hallucinations, seeking help from eye health specialists or stroke nurses is essential. They can provide advice and referrals to appropriate services. It is also crucial to distinguish between hallucinations caused by sight loss and those stemming from other conditions affecting the brain. In the latter case, further evaluation and treatment may be necessary.

Frequently asked questions