Understanding Cerebral Visual Impairment in Children
Amanda Hall Lueck & Gordon N. Dutton, editors
The children who are the subject of this book have identified brain defects. The name has changed recently from cortical visual impairment to cerebral visual impairment (CVI) recognizing that the problems may exist in areas of the brain other than the cortex. The change also recognizes that these problems are on a continuum. In the past only the most severe problems were recognized. I will share the highlights in a few installments.
Large proportions of children with cerebral palsy, hydrocephalus, and other conditions affecting the brain had visual disabilities that had been masked by and ascribed to their overall disorders.
Over 40% of the brain is involved in processing and supporting vision, so it is not surprising that damage to the brain commonly impairs vision in a wide range of ways.
It is important to recognize cerebral visual impairment in children with profound visual impairment, but it can also cause difficulties in those with milder manifestations that can impinge considerably on their ability to perform school tasks such as reading and math, as well as compromise independent orientation and mobility, social interaction, and daily living skills.
Although vision as a sense has typically been associated with the eyes, they comprise only a part of the system that supports and sustains the sense of vision.
The visual brain is a conceptual term referring to the totality of brain elements serving or supporting vision.
In contrast to visual functions (such as visual acuity), functional vision describes how an individual functions using vision and involves evaluation of that person’s visual skills and abilities as applied to the performance of usual tasks of daily life, such as reading. An evaluation of functional vision involves categories that are less precise than measures of visual function, and is often affected by multiple variables at one time.
Visual perception is the act of detecting and recognizing what is seen. Visual cognition is considered an extension of visual perception and involves the capacity to process what is seen, to think about its significance, and to manipulate and use both incoming image data and remembered imagery in the context of creative thought. Visual guidance of movement refers to the mapping of incoming visual information in the mind that is utilized to guide movement of the limbs and body. The conscious visual process of choosing to pay visual attention is an executive function.
Visual dysfunction is applied in this book to disorders of visual perception, visual guidance of movement, and visual attention.
An automatic system exists in our brain that prevents us from bumping into things without our necessarily knowing how we do it. Damage in one part of our brain can result in seemingly paradoxical visual behaviors as some skills are affected and others are not.
The act of recognizing and accurately characterizing the range of visual disorders, and adopting approaches to overcome the resulting difficulties, can be life changing. The person is no longer criticized but is understood and helped.
By observing a child’s daily activities and participating in the collaborative assessment of vision themselves, teachers and family members can better understand how a child functions visually and attempt to see the world “through the child’s eyes”.