WHAT IS CORTICAL VISUAL IMPAIRMENT?
Cortical Visual Impairment (CVI) is a decreased visual response due to a neurological problem affecting the visual part of the brain. Typically, a child with CVI has a normal eye exam or has an eye condition that cannot account for the abnormal visual behavior.
HOW DOES VISION WORK IN CVI?
The eye structure in CVI is usually normal. The eye takes a normal picture of the object and sends the message to the brain. The message is not properly processed or integrated because of the abnormal brain function. Many children with CVI have difficulty visually “latching on” to an object and also filtering out peripheral visual stimuli to isolate the object.
WHAT CAUSES CVI?
CVI is caused by any process that damages the visual parts of the brain. Examples include: stroke, decreased blood supply, decreased oxygenation, brain malformation or infection, hydrocephalus (increased pressure in the brain), seizure, metabolic disease, infection, head trauma and other neurologic disorders.
WHAT VISUAL CHARACTERISTICS ARE ASSOCIATED WITH CVI?
- Distinct color preferences
- Variable level of vision loss, often demonstrating fluctuations over time
- Poor attention to visual stimuli, particularly complex visual and environmental stimuli
- Delay in response to visual stimuli
- Difficulty with visualizing new surroundings or objects
- Preference for looking at lights
- Preference for viewing objects at close range and odd angles
- Better vision when viewing moving objects compared to stationary objects
DOES VISION IMPROVE IN CVI?
As the brain matures new connections can develop in the brain to overcome the initial injury or deficit and improve the function, however it is difficult initially to predict future visual function. Vision improvement may be seen in some children.
CAN CVI BE TREATED?
Treatment of any underlying neurologic disease is essential and should be organized by the primary care physician. It is also important to start early intervention to help stimulate visual development. There is a limited time frame for visual development and it is crucial to have treatment as young as possible (as early as 3 months of age) to maximize improvement.
WHAT TYPE OF STIMULATION IS HELPFUL FOR CHILDREN WITH CVI?
- Large, high contrast, lighted, reflective and moving objects; e.g. mobiles
- Touch or sound to attract child’s attention
- Visual materials presented in a simple uncluttered manner with increasing complexity as tolerated
- Presentation of visual material from different directions/angles
- Variable level of light in environment (some children do better with a lighted toy in dim room initially)
- Extra time for responses to visual stimuli
- Avoidance of over stimulation
- Avoidance of visual tasks when child is hungry, tired, frustrated, etc.
DO CHILDREN WITH CVI NEED AN EYE EXAMINATION?
Yes. Some children with CVI have other associated visual disorders such as structural eye disease, misaligned eyes, or a significant refractive error. A Pediatric Ophthalmologist can evaluate the eyes to see if they are healthy, or if there is an abnormality in the eye that is contributing to the visual issues. Treating these associated conditions may include glasses or eye muscle surgery and can help maximize visual function.