Stroke-Related Vision Loss: Understanding The Impact And Causes

Vision loss is a common occurrence after a stroke, with up to 66% of stroke survivors experiencing some form of visual impairment. This is often due to the stroke injuring part of the brain or affecting the nerves and muscles around the eye. The impact of vision loss on daily life and overall recovery can be significant, and it is important to seek medical attention as soon as possible. While full recovery of vision is rare, some recovery is possible, usually within the first few months after a stroke. Treatments such as vision therapy, glasses, and other tools can help improve vision and overall health.

Temporary vision loss can be a sign of an impending stroke

Vision changes or loss can be a sign of a stroke, and it requires immediate medical attention. Temporary vision loss can be a symptom of a stroke that has already occurred or is about to happen. It is important to note that vision issues may be overlooked following a stroke, either because medical professionals are focused on more severe side effects or because the patient themselves is not fully aware of the extent of their vision loss.

The majority of visual processing occurs in the occipital lobe, located at the back of the brain. Strokes typically affect one side of the brain, and the impact on vision depends on which side is affected. If the right occipital lobe is injured, the left field of vision in each eye may be affected, and vice versa. It is rare for both sides of the brain to be affected, but when it does happen, it can result in blindness.

There are different types of vision loss that can occur after a stroke. Homonymous hemianopia is the loss of one half of the visual field in each eye, giving the feeling of being unable to see out of one eye. Quadrantanopia is the loss of either the upper or lower quarter of the visual field. Eye movement disorders can also occur, impacting the function of the eyes and causing issues such as nystagmus (rapid movement from side to side or up and down) and strabismus (eye turning).

Vision loss after a stroke can have a significant impact on daily life and overall recovery. While some recovery is possible, usually within the first few months, most people with vision loss after a stroke do not fully recover their vision. Training, equipment, and home modifications can help individuals live as independently and safely as possible.

Vision loss can occur after a stroke

Vision Loss After a Stroke

Types of Vision Loss

The different types of vision loss that can occur after a stroke include:

• Homonymous hemianopia: Vision loss that occurs 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 your visual field.
• Scotoma: A blind spot anywhere in your visual field.

Other Vision Issues

Other vision issues that can occur after a stroke include:

• Spatial inattention: This happens when your brain doesn't process visual information on the side affected by the stroke.
• Eye movement disorders: Impaired function of the eyes due to damage to the nerves and muscles around the eyes.
• Nystagmus: Rapid movement of the eyes from side to side, up and down, etc.
• Strabismus: Eye turning inward, outward, etc.
• Diplopia: Double vision.
• Oculomotor dysfunction: Tracking issues, convergence insufficiency, cranial nerve palsy, etc.
• Issues with balance, coordination, or depth perception.
• Dry eyes and light sensitivity: Irritated or burning eyes due to issues with blinking or closing the eyes.

Brain Areas Affecting Vision

The occipital lobe, located at the back of the brain, is the area where visual processing takes place. The brainstem controls eye movement, balance, stability, and the ability to make sense of objects in the environment. Strokes affecting these areas of the brain are more likely to result in vision problems.

Diagnosis and Treatment

Vision loss after a stroke can be diagnosed by ophthalmologists, optometrists, neurologists, neuro-ophthalmologists, and neuro-optometrists. Treatment options include vision therapy, glasses, prism lenses, eye patches, and eye drops for dry eyes. Training, equipment, and home modifications can also help individuals with vision loss after a stroke to live more independently and safely.

Vision loss after a stroke is likely more common than you think

The brain is an extremely complex organ that controls many body functions, and a stroke occurs when the blood that brings oxygen to the brain stops flowing, causing brain cells to die. The impact of a stroke on vision depends on the location and extent of brain tissue affected. The occipital lobe, located at the back of the brain, is the main vision centre, but all brain lobes receive visual information. The brain stem, situated at the base of the brain, controls eye movements, sensations related to balance and stability, and the ability to recognise and understand objects.

There are several types of vision loss that can occur after a stroke:

• Homonymous hemianopia: Loss of vision in the right or left half of the visual field in each eye.
• Homonymous quadrantanopia: Loss of vision in either the upper or lower quarters of the visual field.
• Scotoma: A blind spot in one or both eyes.

Other visual challenges that can arise after a stroke include eye movement disorders, such as nystagmus (rapid eye movements), strabismus (eye turning), diplopia (double vision), and oculomotor dysfunction (tracking issues). Dry eyes can also develop due to difficulty blinking or fully closing the eyes, leading to irritation, burning, or blurry vision.

Vision rehabilitation and proper diagnosis can help with recovery and improve daily activities. Eye doctors, brain doctors, and brain-eye doctor specialists can diagnose vision problems and develop treatment plans, which may include rehabilitation therapies to help survivors compensate for losses and regain function. While most people who experience vision loss due to a stroke don't fully regain their vision, some recovery is possible.

Homonymous hemianopia is the loss of one half of the visual field in each eye

Homonymous hemianopia (also known as homonymous hemianopsia or HH) is a symptom where you can only see one side—right or left—of the visual field of each of your eyes. In other words, it is the loss of one half of the visual field in each eye.

The visual field refers to everything you see when your eyes are open. When your vision is working correctly, everything on the right side of your visual field goes to the left side of your brain, and vice versa. This is made possible by the optic nerve fibres, which carry visual information from both sides until they reach a point in the brain called the optic chiasm, where some of the fibres change direction.

Homonymous hemianopia affects signals from the same side of both eyes travelling together after passing the chiasm. This is why HH causes vision loss on the same side of both eyes. It is classified as a visual field defect, and the conditions that cause it all affect the brain. It usually occurs suddenly, but it can also develop gradually.

HH is often a symptom of a life-threatening emergency condition, such as a stroke, brain bleed, or transient ischemic attack (TIA). When someone experiences HH for the first time, it is considered a medical emergency.

There are different types of homonymous hemianopia:

• Right hemianopia, which causes a loss of vision in the right half of each eye.
• Left hemianopia, which causes a loss of vision in the left half of each eye.
• Superior hemianopia, which causes a loss of vision in the upper half of each eye.
• Inferior hemianopia, which causes a loss of vision in the lower half of each eye.

Quadrantanopia is the loss of either the upper or lower quarter of the visual field

A stroke is a "brain attack" that occurs when blood stops flowing to the brain, starving it of oxygen and causing brain cells to die. Vision loss is a common occurrence after a stroke, with about 65% of stroke survivors experiencing some form of vision problem. This is because the brain is responsible for processing what we see, including colour, size, and shape, and understanding the significance of what's in front of us.

The impact of Quadrantanopia can vary depending on which quarter of the visual field is affected. If the upper quarter is lost, individuals may have difficulty reading as the field deficit crosses the horizontal plane. They may also bump into objects positioned above their head that are in their blind field. If the lower quarter is lost, individuals may experience challenges with general mobility and recognising people or objects.

While some recovery from vision loss after a stroke is possible, especially in the first few months, most people do not fully regain their vision. Treatment options include prism lenses, which can shift images from the non-seeing to the seeing visual field, and eye drops or ointments for associated dry eye symptoms.

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