Cortical Visual Impairment

Cortical Visual Impairment (CVI), a temporary or permanent visual impairment, results in a disturbance of the posterior visual pathways and/or the occipital lobes of the brain. The visual impairment can range from a severe visual impairment to complete and total blindness, and the severity normally depends upon the time of onset, the location, and the intensity. The condition indicates that the visual systems of the brain do not consistently understand or interpret what the eyes see.

Cortical Visual Impairment can be caused in a variety of ways, including asphyxia, perinatal hypoxia ischemia, developmental brain defects, head injury, hydrocephalus, and infections of the central nervous system, such as meningitis and encephalitis.

CVI is the leading cause of bilateral visual impairment in children in western countries. Discovering CVI reflects better methods for identifying visual impairment due to CNS injury and also advances in perinatal care, which has increased the survival rate of children with neurological mobidity.

Children with CVI initially appear blind; however, their vision tends to improve. Therefore, CVI is a more appropriate than Cortical Blindness. CVI often coexists with ocular visual loss. Therefore, children suffering from CVI should often be seen by both a pediatric neurologist and a pediatric ophthalmologist.

Diagnosing a child with Cortical Visual Impairment can be an intricate task, because it is complicated to understand, even though it is the leading cause of vision problems in children. Many children with CVI don't appear visually impaired, so the condition may go unnoticed for quite some time, especially if there are other medical issues that are of major focus. Part of the problem is that it reflects problems in the processing part of the visual system which is often difficult to define.

The diagnosis is made when a child has poor or no visual response and yet has a normal papillary reactions and a normal eye examination. The child's eye movements are most often normal. The visual functioning will be variable. The result of a Magnetic Resonance Imaging (MRI) test, along with an evaluation on how the child is functioning visually, provides the basis for diagnosis. There are also other ways of determining CVI, such as using ERG to rule out retinal problems and/or VEP to give some brain reception information related to vision. Brain scans and neuro-imaging are also of value in determining the cause of some symptoms and to rule out some other concerns.

Children with CVI have different abilities and needs. A carefully planned habilitation is critical, as well as a full evaluation by a number of professionals. The evaluation team could include teachers, Physical Therapists, Occupational Therapists, Speech Therapists, and Orientation and Mobility Specialists.

There are many different characteristics of CVI. The functional use of vision is obviously affected. It's sometimes been described as holding several layers of crinkled saran wrap in front of your eyes.

However, there is hope because CVI sometimes improves. Vision is both physiological and learned. Therefore, both aspects contribute to the changes with CVI that may occur for up to 6 years of life. The cause, as well as the age of the child, may influence the chances of apparent improvement.

Another characteristic is that visual alertness may appear to fluctuate. Sometimes the child seems to see better than other times. Moreover, many CVI children are attracted to lights, more commonly fluorescent lights. They may turn to lights and stare. It is beneficial to occasionally draw their attention outward for more purposeful involvement.

Some children with CVI look away from an object as they are reaching for it. This may be an adaptation for visual field or the use of peripheral vision to look. Further, once the object has been located, some multi-handicapped children with motor problems will turn away to concentrate on their grasping since the unclear visual component also requires concentration and looking does not reinforce for the effort.

Many children with CVI mouth objects. They may be picking up detail information with their mouth, thereby confirming blurred visual messages. Also, purposeful handling of objects is critical in developing an associative foundation for language. The child may even "look" for an object by its label once the connection has been physically put together.

Other characteristics of CVI include, but are not limited to, rapid horizontal head shaking or eye pressing, difficulty differentiating the background and foreground of visual information, and being able to see better when told what to look for ahead of time.

Though there are many characteristics to CVI, there are also many myths. It was originally thought that children with CVI are visually inattentive and poorly motive. It was also thought that children whose visual cortex was damaged were Cortically Blinded or that children with CVI are completely blind. None of the aforementioned is true, according to current knowledge in the field.

The incidence of CVI is increasing. In a study of five Nordic countries, Rosenberg and coworkers noted that brain damage accounts for a growing number of cases of childhood visual impairment. They suggested that better medical care has lowered the mortality rate of children with severe medical problems.

Although CVI alone is not life threatening, its associated neurological disorders may have been fatal in the past. In one study from Northern California, CVI was found to be the leading cause of visual impairment in children under the age of 5 years. In developed countries, CVI has become more frequent and can be considered one of the major causes of visual handicap in children of developed regions.

Just less than 10% of the current population of visually impaired children in British Columbia is cortically visually impaired, according to Dr. James Jan, a pediatric neurologist in British Columbia. His practice has included many children with this diagnosis and he and his colleagues have made several observations about the "visual behaviors" associated with cortical visual impairment.

Through Dr. Jan's work, he has discovered that children who have Cortical Visual Impairment will be attracted to familiarity, and will often neglect items that are new to the child. Dr. Jan says to "think about what objects the child is involved with during his or her daily care activities. Make these objects part of his or her vocabulary (touch, function, sight)." He goes on to list examples, such as bottle/cup - drinking, bowl/plate/spoon - eating, washcloth or favorite bath toy - bathing, or music toy - bedtime.

All children with CVI have the right for input from the perspective of being seriously