WHAT IS CORTICAL/CEREBRAL VISUAL IMPAIRMENT (CVI)?
For many people, the act of seeing is only associated with the health of the eyes; however, the visual process primarily takes place in the brain. While the eyes serve as a camera that collects light from the world, the brain is the actual center that transforms this data into a meaningful image, an emotion, or an action.
Indeed, more than 40% of the brain is dedicated, directly or indirectly, to the processing of visual information. Cerebral Visual Impairment (CVI) is a condition in which, despite healthy eyes, an individual perceives the world "differently" due to a malfunction, damage, or malformation in the brain's visual processing pathways or centers.
A World Unseen by Healthy Eyes
The most striking feature that distinguishes CVI from other vision problems is that a problem often cannot be detected through standard eye examinations or MRI scans. Thousands of children are being pushed out of the medical and educational systems under the assumption that they can "see" because their eyes are healthy
You should know that:
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Scoring "perfectly" on an eye test does not prove the absence of CVI; this is a data processing problem.
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The difficulties experienced are often confused with conditions such as learning disabilities, ADHD, or autism.
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CVI is not a disease, but a state of "alternative normality" in the way the brain organizes the visual world
The Vision Window”: Understanding a Constantly Changing World
For a child with CVI, vision does not function as a fixed, always-open window. This "Vision Window" can constantly fluctuate, narrow, or lose its focus depending on factors such as attention, fatigue, environmental clutter, movement, sound, and sensory overload.
The "Vision Window" concept, which we emphasize at AGAH-DER, helps us understand how effectively the brain can organize visual information at any given moment and how the child relates to their surroundings. At certain times, a child may perceive a single object with great clarity, while everything else in their immediate environment seems to disappear—a clinical manifestation of impaired parallel processing or simultanagnosia.
Consequently, the challenges faced by children with CVI are often misinterpreted as "attention deficit," "unwillingness," or "non-compliance"
For instance, in an environment with high visual clutter, a child might be unable to locate a favorite toy among dozens of objects. However, when the same object is placed on a plain, single-colored background, they may notice it immediately. Similarly, in a classroom setting where the teacher’s voice, writings on the board, moving classmates, and environmental details must be processed simultaneously, the child’s visual window may narrow significantly due to sensory competition.
The Vision Window can further contract with fatigue. While some children can organize their surroundings more effectively in the early hours of the day, they may face marked difficulties identifying familiar faces, tracking moving objects, or navigating their environment during post-school hours.
Children with CVI may sometimes "stop looking" in order to listen. This is because some brains struggle to process intense visual and auditory information at the same time. The fact that a child is not looking at you does not necessarily mean they are not listening; on the contrary, they may be attempting to understand you by reducing their sensory load.
Perception of movement and depth is also heavily influenced by the fluctuating nature of this window. A shadow might be perceived as a deep pit, and it may become difficult to discern exactly where steps begin or end. A fast-moving ball or a running friend might suddenly become "invisible" to the child due to the complexities of motion perception.
In a crowded schoolyard, a child may be unable to locate their mother; however, upon hearing her voice or noticing a distinct color cue, the Vision Window can reorganize and orient toward the correct direction.