Vision depends on the brain as much as it does on the eyes. The complex process for us to see starts with light entering the eye. That light is converted into electrical signals that travel to the brain via the optic nerve, a bundle of more than 1 million nerve fibers. The brain processes the electrical signals, which allows us to see shapes, movement, depth, and color.
Cortical visual impairment (CVI), also called cerebral visual impairment or cortical blindness, refers to vision loss that is caused by damage to the pathways between the eye and the brain and the specific parts of the brain responsible for vision. In many cases, people with CVI have completely normal eyes.
Individuals with CVI may have a variety of visual impairments including decreased visual acuity and visual field deficits. Individuals with CVI may have visual processing impairment that interferes with their ability to, for example, identify faces, find objects in a cluttered environment, or see clearly in a noisy room. CVI-related impairments can be mild to severe leading to functional limitations that impact an individual’s learning, mobility, development, independence, and quality of life.
CVI is caused by neurological (brain) damage. Neurological damage may occur when a baby is born prematurely, but such damage may also occur in infants born at term.
The most common cause of CVI-related brain damage is hypoxia (when the brain does not get enough oxygen). The condition can also be caused by head injury, abnormalities in brain formation, hydrocephalus (increased fluid and pressure in the brain), seizures, metabolic diseases, infection, or neurologic disorders.
The incidence of CVI is increasing in part because advances in the ability to diagnose and treat complications in newborns have helped more babies survive when there is neurological damage.
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