Cerebral Visual Impairment (CVI) is a neurological condition impacting how the brain processes visual information. Individuals with CVI may have healthy eyes and good visual acuity, yet their brains struggle to make sense of what they see. This impairment results from damage to the visual pathways or the processing centers within the brain, often occurring before, during, or shortly after birth due to events like lack of oxygen or premature birth. CVI is currently considered one of the most common causes of visual impairment in children.
Key Visual Behaviors and Responses
A defining characteristic of CVI is visual latency, which manifests as a noticeable delay between the moment a visual target is presented and when the individual actually responds to it. This delayed response can sometimes be mistakenly interpreted as a lack of interest or inattention, but it simply reflects the extended time required for the brain to process the visual signal.
Many people with CVI show a strong color preference, often favoring highly saturated colors like red or yellow to capture and maintain their visual attention. These bright, single colors may act as an anchor, helping the visual system lock onto an object in a way that more muted or complex colors do not.
The need for movement is another common behavior, where an object must be moving to elicit or sustain visual regard. A stationary toy might be ignored, but the moment it is moved or has a reflective surface, it becomes visually accessible.
Individuals may also demonstrate a visual field preference, consistently turning their head to look out of a specific portion of their vision, such as the lower left field. This behavior suggests that a particular area of the visual field is more accessible for processing than others.
Some individuals with CVI exhibit light gazing, where they are strongly attracted to sources of light, such as windows, lamps, or back-lit screens. This attraction may be an early visual response that is easier for the damaged visual system to process than complex objects.
Interpreting Reactions to Visual Complexity
Difficulty in processing visual complexity is a key challenge in CVI. This complexity can apply to the target object itself, the surrounding visual environment, or even simultaneous multisensory input. Individuals with CVI often have trouble finding an object when it is surrounded by other items, a phenomenon known as visual crowding. They might see a single toy easily when it is presented alone, but fail to locate it when it is placed among a group of similar items.
The impact of background complexity is also significant, meaning a child might struggle to distinguish a target object from a busy or patterned backdrop. For instance, a simple block may be invisible on a brightly colored, patterned rug, but instantly seen when placed against a plain surface. The brain must expend extra effort to filter out irrelevant visual noise, which rapidly leads to visual fatigue.
This difficulty extends to social complexity, making it hard to process faces, especially in a crowd or when a face is changing rapidly with emotion or speech. People with CVI may look away during conversation or struggle to recognize a person if their hair or clothing changes, relying instead on auditory cues like voice. This highlights the look/see distinction, where the individual may physically look in the direction of an object (the “look”) but be unable to visually process or understand what they are seeing (the “see”).
Reliance on Non-Visual Senses
To compensate for unreliable visual processing, individuals with CVI often develop a strong reliance on non-visual senses. They use touch and hearing to gather information about the world that their visual system cannot consistently provide.
Tactile confirmation is a common compensatory strategy, where the individual needs to touch or mouth an object immediately after visually locating it to confirm its presence and identity. This touch-first approach helps build a reliable, three-dimensional understanding of their environment. Auditory guidance also becomes important for navigation, with the person relying heavily on sound cues like voices, footsteps, or the noise a toy makes to orient themselves. This sensory integration allows the individual to construct a mental map of their surroundings, using hearing and touch to fill in the visual gaps.