Stroke

The brain is an extremely complex organ that controls various body functions. If a stroke occurs and blood flow can’t reach the region that controls a particular body function, that part of the body won’t work as it should.

If the stroke occurs toward the back of the brain, for instance, it’s likely that some disability involving vision will result. The effects of a stroke depend primarily on the location of the obstruction and the extent of brain tissue affected.

However, because one side of the brain controls the opposite side of the body, a stroke affecting one side will typically result in neurological complications on the other side of the body it affects.

The influence of a stroke on your vision

A stroke (also referred to as a cerebrovascular accident, or CVA for short) occurs when the blood supply to part of the brain is suddenly interrupted or when a blood vessel in the brain bursts, spilling blood into the spaces surrounding brain cells. Brain cells die when they no longer receive oxygen and nutrients from the blood or when there is sudden bleeding into or around the brain.

Although stroke is a disorder of the brain, it can affect the entire body. Depending on the location of the stroke, people may suffer loss of motor coordination, neurological and perceptual function, as well as experience double vision, blurring, headaches, or inability to detect obstacles.

Visual field loss

About two-thirds of stroke survivors have visual impairment that typically relates to diminished central or peripheral vision, eye movement abnormalities, or visual perceptual defects. A wide range of visual disorders can occur following a stroke. Frequently, they give rise to visual symptoms such as blurred or altered vision, double or jumbled vision, loss of visual field, reading difficulty, extreme sensitivity to bright light, and inability to recognize familiar objects or people. 

The impact of visual impairment is clear with issues relating to driving, activities of daily living, and social engagement, among others.  Given the high rate of visual symptoms and known impact, it is recommended that all stroke survivors receive comprehensive screening for visual disorders in the early days following a stroke as they may warrant referral for a specialist’s assessment and targeted treatment specific to their type of visual impairment.

Just as with a Traumatic Brain Injury (TBI), when a person has a stroke, often one type of rehabilitation is not enough to address all of his/her needs. Rehabilitation following a CVA most often requires extensive vision neuro rehabilitation therapy along with physical and occupational therapy. An individual’s visual rehabilitative needs should be addressed as early as possible by our Neuro-Optometric Rehabilitation Optometrist, who will work with other rehabilitation team members to help the stroke survivor learn new ways of performing tasks to circumvent or compensate for any residual disabilities.

What visual disturbances can occur?

Many stroke survivors report vision difficulties, including poor visual memory, disruption in balance, decreased depth perception and reading problems. Rehabilitation therapy can help improve many conditions.  Here are some common issues stroke survivors experience:

Spatial Inattention: 

This problem, often called neglect can result in not paying attention to the side of your body affected by stroke. For example, you may not touch food on the left side of your plate or shave the left side of your face. In some cases, it can seem like there’s no left side of the body because your brain is not processing information from that side very efficiently. Rehabilitation involves learning to scan from side to side – finding items on a table and a wall, for instance. This problem also affects the ability to judge space, so therapy may involve touching things at different distances or using a full-length mirror to help process visual information. This treatment should be practiced several minutes at a time, five times per week.

Seeing Double:  

With double vision, you lose depth perception. An eye patch can help in the early stages of recovery, but it doesn’t fix the entire problem. It just reduces the information the brain has to process. Special prism lenses help to melt the two images back into one, reducing the confusion and disorientation.

Oculomotor dysfunction:

This occurs when your eyes can’t track or move smoothly between objects. This condition often causes reading problems. It may also affect walking. This type of problem rarely gets better without therapy.

Visual Midline Shift:

When the perceptual ‘calibration’ of the visual system is disrupted, balance and orientation is affected, as the subconscious brain may think the floor is tilted. The walls might also appear tilted, and your body subconsciously tilts or lean over to compensate. Addressing this problem involves balance activities such as training to put more weight on the foot of your unaffected side. Therapists also use special prism glasses called yoked prisms that can affect spatial perception and body posture.

Field Losses:

A stroke can cause a lesion in the brain involving the optic nerve that results in a hemianopsia, commonly called a visual field loss. This can involve several areas in both eyes. Reading can be a chore, and therapy may involve using a line guide or a device that helps isolate the lines when reading. Relaxation and breathing techniques can help, too. Developing efficient scanning techniques is a big part of rehabilitation.

Rehabilitating vision can have a big impact on other therapies, such as physical, occupational and speech therapy.