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...
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