Vision Problems Associated with Cerebral Palsy

Cerebral palsy (CP) is a condition characterized by motor function impairments. Both genetic and environmental factors can play a role in the development of cerebral palsy, but it is most often caused by infant brain damage that occurs shortly before birth, during the birthing process, or in the neonatal period.

Visual processing involves a large part of the central nervous system. For this reason, the types of brain damage that cause cerebral palsy – especially hypoxic-ischemic encephalopathy (HIE) – frequently also result in vision problems. Periventricular leukomalacia (PVL), injury to the brain’s white matter, is very often associated with both cerebral palsy and cerebral visual impairments (1).

Approximately 50% of children with cerebral palsy have some form of visual impairment (2). The severity of vision loss tends to increase with the severity of cerebral palsy, as measured by the GMFCS score (1), and with the number of limbs affected (1, 2). In general, visual impairments are thought to be more common in children with spastic cerebral palsy than those with athetoid or ataxic types (3).

The most common vision problems in children with cerebral palsy are strabismus (which makes up 55.7 percent of vision problems associated with CP) and refractive errors (which make up 20.7 percent). Although both of these conditions can be minor, 18.9 percent of children with cerebral palsy are affected by severe visual loss (2).

Strabismus is a condition in which the eyes look in different directions. It is most often associated with spastic quadriplegic and hypotonic cerebral palsy.

People with strabismus may have esotropia (in which one or both eyes tend to look inward, toward the nose) or exotropia (in which one or both eyes tend to look outward, away from the nose). In rare cases, the eyes may be vertically divergent; in other words, one eye gazes higher than the other.

Strabismus can also be classified as latent or manifest. Latent strabismus is only present when the other eye is covered – muscle activity corrects it when the eyes are both uncovered and need to work together. Manifest strabismus remains when both eyes are uncovered, and therefore may be more noticeable. Children with cerebral palsy are more likely to develop manifest strabismus, possibly because they lack the muscular coordination necessary to make the appropriate corrections.

Although strabismus does not always significantly affect one’s ability to see, it often causes amblyopia. People with amblyopia have impaired vision because nerve pathways between an eye and the brain are not working properly. In some cases, amblyopia affects both eyes. In others, the brain begins to favor one over the other, causing the neglected eye to wander (4). Readers may be more familiar with the colloquial phrase “lazy eye,” although it is important to note that many find this offensive.

Amblyopia can lead to poor hand-eye coordination and gross motor skills in children with no other disabilities. In children with cerebral palsy, a lack of binocular vision can make postural and movement issues more pronounced (5).

People may seek treatment for strabismus in order to prevent/improve vision problems, as well as to avoid societal issues. Unfortunately, research has shown that people with strabismus are more likely to struggle with self-image, interpersonal relationships, and even securing employment (4, 5).

In general, intervention earlier in life is more successful in correcting vision problems. For this reason, it is critical that children with cerebral palsy have frequent eye exams (1). Moreover, it is important to realize that children with severe motor or cognitive impairments may be unable to communicate about visual difficulties.

Management of strabismus centers on straightening the eyes and restoring binocular vision. In general, intervention earlier in life is more successful.

Treatments include:

• Surgeries: One study found that after an average of two surgical procedures, more than half of children with strabismus and cerebral palsy were able to achieve good eye alignment. This was true of children with both mild and severe cerebral palsy. However, children with more severe cerebral palsy had a lower chance of gaining binocular vision even when their eyes had been successfully aligned (5).
• Eyeglasses: People with strabismus can be prescribed glasses with prisms to correct eye misalignment.
• Eye patches: Putting a patch over the stronger eye can lessen the effects of amblyopia (6).

A refractive error is a visual condition in which the shape of the eye itself stops light from focusing directly on the retina. The retina is located in the back of the eyeball, and sends visual information to the brain.

The following are some common types of refractive errors:

• Myopia: People with myopia, also known as nearsightedness, struggle to see far-away objects.
• Hyperopia: People with hyperopia, also known as farsightedness, struggle to see nearby objects.
• Astigmatism: People who have an astigmatism may report that images seem blurry and stretched out.

Many people with refractive errors wear prescription eyeglasses or contact lenses. Others opt for refractive surgery, which changes the shape of the cornea and allows rays of light to focus more directly on the retina (7).

Sometimes, children develop cerebral palsy and associated visual impairments despite having medical care from competent professionals who did everything in their power to prevent harm. Unfortunately, these conditions can also result from acts of medical malpractice.

For example, doctors and nurses may fail to monitor for and/or appropriately respond to signs of fetal distress. These are signs that a baby is being deprived of oxygen and is in need of immediate intervention (such as an emergency C-section). Other problematic behaviors include deviating from standard of care for a high-risk pregnancy, inducing labor when it is not safe to do so, or using risky birth-assisting tools such as forceps and vacuum extractors when they are not indicated.