Neurological Visual Impairment
10 NVI Characteristics
Color Preference
- The preference for or ability to only see a specific color
- Usually a color that has been present in a child's life (what color their favorite toy/object is)
- Common colors for color preference are red and yellow
- Preferred color becomes a visual anchor for highlighting information and selecting educational materials
- The object should be the preferred color, not the background when presenting materials
Need for Movement
- Visual attention is drawn to items that move
- Some may not be able to see something until it moves
- Drawn to objects that have the appearance of movement (mylar, shiny objects)
- Some individuals move their bodies to create the movement needed to see
Visual Latency
- A delay between an object's presentation and when it is looked at
- May increase when ill, stressed, or tired
- Warm-up activities can help decrease latency
- Provide verbal information prior to presenting an item and keep silent while waiting for visual attention
Visual field preferences
- Most often have a preference for a peripheral field (to the side)
- Most have a lower visual field loss that affects safe travel
Difficulties with visual complexity (4 different areas)
- Complexity of patterns on the surface of objects
- May only look at objects of a single color at first
- Then moving on to 2 colored objects with one of the colors being their preferred color
- Chosen objects can gradually increase in complexity with more colors and patterns
- Complexity of visual array
- May only be able to visually focus on one item at a time
- Difficulty with clutter
- Have a single color-black or white background is helpful
- Complexity of human faces
- May not be able to look into faces or only familiar faces when they're not talking
- May appear to look through someone rather than at
- Complexity of sensory environment
- Some may only be able to attend to one sense at a time (vision, hearing, tactual)
- Lowering background noise is always helpful
Need for light
- Prolonged periods of gazing at natural or artificial light
- Uses a visually neutral "time out" to rest or use another sense (hearing, touch)
- Light can be used to draw and keep attention (light box, ipad)
Difficulty with distance viewing
- Seems to be nearsighted
- Linked to complexity of array- the closer an object is, the more the background is covered
Atypical visual reflexes
- Absence or delayed blink reflex when touched on the bridge of the nose
- Absence or delayed blink to a visual threat coming toward the eyes at midline
- There is no intervention for this characteristics, it is an indicator of overall visual ability
Difficulty with visual novelty
- Prefer to view objects that are familiar
- New objects need to be taught and should have similar characteristics to familiar objects
Absence of visually guided reach
- May look at an object, then look away while reaching
- May be able to look and reach with single color object and high contrast, but then not be able to do a visually guided reach with a more complex item on a more complex background