CVI Home
Articles and Videos
Research
APH Home

Programming for Students Who Have Severe Cortical Visual Impairments

Nancy Levack, with contributions from Gretchen Stone and Virginia Bishop

Originally appeared in Low Vision: A Resource Guide with Adaptations for Students with Visual Impairments

When students have sustained severe brain damage that affects the visual pathways and the visual cortex, they are said to have a cortical visual impairment (Groenveld, Jan & Leader, 1990). These students can have normal eye capacity but once the image reaches the brain the information is not interpreted or processed accurately. Students with cortical visual impairment differ from students who have an impairment in the eye. While students with cortical visual impairments may see an accurate visual image, for some reason they cannot interpret it accurately. On the other hand, students with eye disorders have difficulty obtaining a good visual image, but usually have little or no difficulty processing and interpreting the visual information accurately, once enough information is present. Some students have both cortical visual impairments and eye disorders.

Students with cortical visual impairment need help to successfully decode the visual images that they receive. Some guidelines for helping these students develop their visual efficiency include:

• Use other sensory cues to stimulate or support the visual information as it is presented to the student. Encourage exploration by touch; then if the student has not looked at it, ask her to do so.
  
  
• Avoid visual over stimulation by introducing items one at a time in an uncluttered environment.
  
  
• When using other sensory cues to stimulate visual performance use only one sense at a time. This will help students integrate information and to make it easier to determine which sense gives the student the most effective information. If a student is given many new objects that have strong visual and tactual qualities as well as produce a unique scent or smell, it is difficult to identify which of these qualities the student is responding to. Once it is clear which sensory qualities give the student the most consistent information, objects that have multiple sensory characteristics can be used.
  
  
• Some students will consistently look away from an object in specific tasks and perform the task tactually, deliberately avoiding using their vision. While the cause of this behavior is still unproven, looking away seems to help them complete the task. Therefore, it would not be helpful, in this instance, to try to teach them to use vision to look at a task at the "critical moment".
  
  
• Watch for preference in color, shape, size, movement, and field.
  
  
• Make changes gradually since processing information is difficult for these students. It is important to build in as much familiarity and predictability as possible. It may be necessary to limit the number of activities and even the number of people who work with a student.
  
  
• Try shaking or moving objects as they are brought into students' line of vision, when introducing them. Moving objects can sometimes be seen more easily than stationary ones.
  
  
• Determine the best position for students to use their eyes. Sitting may be the most difficult position for them because they must exert so much energy maintaining the sitting position, that they have little energy or attention left to focus on the visual task.
  
  
• Visual cues should be bold, simple and consistently used throughout programming. Generalization can occur more easily when the same visual cues or objects are used in different activities.
  
  
• Present visual stimuli in a simple figure-ground environment. Avoid visual clutter and maintain high contrast between the background and the object being viewed. Students may bring the object close to their eyes to block out extraneous background information, so they can focus more easily.
  
  

Additional information about cortical visual impairment can be found on the chart on page 131.

Cortical Visual Impairment

This is a chart in the original publication (page 131).

Physical Characteristics
Damage to the visual cortex or the posterior visual pathways. Pervasive neurological disorders such as cerebral palsy, epilepsy, hydrocephalus, learning disabilities, or deafness may be present. Occasionally optic nerve atrophy, optic nerve hypoplasia, retinal abnormalities and other ocular lesions occur. Spatial confusion is common.

Cause
Caused by anoxia at birth, a head injury, infections to the central nervous system (such as encephalitis and meningitis), shunt failure, or a genetic malformation.

Possible Resulting Effect on Vision
Fluctuation in visual functioning, eye structure may be healthy and intact, sometimes absence of nystagmus, inattention to visual stimuli, preference of touch over vision as the primary exploratory sense, difficulty seeing objects or pictures which are placed close together, difficulty discriminating figure-ground, may have more peripheral than central vision or vice versa. Color perception is generally intact. Visual improvement sometimes occurs over a period of time after the initial insult to the brain. Light gazing frequently occurs. Students may bring objects close to their eyes to block out the extraneous visual clutter in order to concentrate more easily on the object.

Adaptations
High illumination, bright contrast in material, using consistent visual cues throughout different settings such as school, home and the community. A combination of reading media may be necessary. See pages 48 and 49 for more discussion on considerations for programming.

Educational Considerations
Most students who have a cortical visual impairment are also multiply impaired. It is necessary to determine which sensory system gives most accurate information to the student and then pair visual skills with that system. Visual input must be controlled to prevent "visual overloading". Visual images should be simple and presented in isolation. Repetition and routines are very helpful. Tell students what they are seeing and encourage them to feel it and explore it while learning about it. Color coding simple pictures or shapes gives an additional cue for recognition. Restrict the number of people who are directly involved in intervention. When preparing reading materials, use a contrasting paper, template or marker to block out some of the visual information, or space objects farther apart on a page. Demonstrate how to use a finger to move from one object to the next on a page. Simplify illustrations. Fluctuations in visual performance may be reduced by eliminating tiredness, extraneous noise and other distractors. It may be necessary to turn off a light or use diffused lighting to get students to focus on a task.

Information about Low Vision: A Resource Guide with Adaptations for for Students with Visual Impairments by Nancy Levack: