| Home | Site Search | Outreach | See/Hear Index |
Winter 2001 Table of Contents
Versión Español de este artículo (Spanish Version)
By Sam Morgan, Education Specialist
Fact Sheet reprinted with permission from California Deafblind Services
Neurological Visual Impairment (NVI) is now the preferred name for a type of vision impairment that has been and is still referred to as Cortical Visual Impairment or Cortical Blindness. NVI is now divided into three categories: Cortical Visual Impairment, Delayed Visual Maturation, and Cortical Blindness. These divisions are made according to what area of the brain has been effected.
A variety of studies indicate that the percentage of children with vision impairments who have NVI is between 3.6 and 21%, making it the major cause of vision impairment in children who are deaf-blind. NVI occurs when the part of the brain that is responsible for seeing is damaged. In other words the eye itself is normal, but the brain does not process the information properly. NVI has a variety of causes, including, but not limited to, lack of oxygen before, during, and after birth, viral or bacterial illness such as meningitis and cytomegalovirus, or traumatic brain injury. These children can but do not always have additional disabilities. Other types of vision impairments such as optic atrophy (defect of the optic nerve resulting in the inability of the nerve to conduct images to the brain) and optic nerve hypoplasia (a vision impairment caused by a congenital defect of the optic disk) are more common in children with NVI.
NVI effects vision in a variety of ways and causes vision loss that can be from mild to severe, temporary or permanent. There is no way to predict what a young child's vision will be like as they mature but many children with NVI experience improvement in their vision. Fluctuating vision is common. This is most pronounced in children with seizure disorders or in those on certain medications such as Dilantin, Tegretol, or Phenobarbital. A child may be able to see an object one day and be unable to the next. These children may also have better peripheral than central vision and thus look at objects out of the side of their eye. They may have visual field losses that are not symmetrical (one eye may be worse than the other). This uneven loss does not necessarily correspond to hand function. If the left eye is better than the right, the left hand is not necessarily stronger than the right.
Children with NVI experience problems with specific types of visual tasks. They have difficulty with figure-ground (seeing an object instead of the background), and with complex visual displays such as cluttered pictures (a picture of five different animals instead of two). Spatial confusion is common; for example being unable to locate their chair even though they can see it. They may also be visually inattentive, not wanting to look at objects, and may prefer their sense of touch. It is common to see a child turn his/her head away as they explore an object with their hands. Seeing with NVI can be compared with trying to listen to one voice in a noisy room or to speaking a foreign language.
Vision stimulation is proven to help most children with vision impairments improve the way they use their vision; this is especially true of children with NVI. For vision stimulation to be effective it needs to happen in everyday real life situations, not only in therapy sessions. Identifying colors in an activity, visually tracking their classmate as they move across the room, and identifying the shape of every day objects are examples.
Levack, N. (1991). Low Vision: A Resource Guide with Adaptations for Students with Visual Impairments. Austin: Texas School for the Blind.
Morse, M.T. (1990). Cortical Visual Impairment in Young Children with Multiple Disabilities, Journal of Visual Impairment and Blindness, 84, 200-203.
Takeshita, B. (1996, March). Neurological Visual Impairment. Paper presented at the annual conference of the California Transcribers and Educators of the Visually Handicapped.
Fact sheets from California Deaf-Blind Services are to be used by both families and professionals serving individuals with dual sensory impairments. The information applies to students 0-22 years of age. The purpose of the fact sheet is to give general information on a specific topic. More specific information for an individual student can be provided through individualized technical assistance available from California Deafblind Services. The fact sheet is a starting point for further information.
| Winter 2001 Table of Contents | Send EMail to SEE / HEAR |
Please complete the comment form or send comments and suggestions to: Jim Allan (Webmaster-Jim Allan)
Last Revision: July 30, 2002winter01/nvi.htm