Neurological Visual Impairment

Also Known as: Cortical Visual Impairment, Delayed Visual Maturation, Cortical Blindness

(fact sheet from CA Deaf-Blind Services)

Neurological Visual Impairment (NVI) is now the preferred name for a type of vision impairment that has been and is still referred to as Cortical Visual Impairment or Cortical Blindness. NVI is now divided into three categories: Cortical Visual Impairment, Delayed Visual Maturation, and Cortical Blindness. These divisions are made according to what area of the brain has been effected.

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NVI effects vision in a variety of ways and causes vision loss that can be from mild to severe, temporary or permanent. There is no way to predict what a young child's vision will be like as they mature but many children with NVI experience improvement in their vision. Fluctuating vision is common. This is most pronounced in children with seizure disorders or in those on certain medications such as Dilantin, Tegretol, or Phenobarbital. A child may be able to see an object one day and be unable to the next. These children may also have better peripheral than central vision and thus look at objects out of the side of their eye. They may have visual field losses that are not symmetrical (one eye may be worse than the other). This uneven loss does not necessarily correspond to hand function. If the left eye is better than the right, the left hand is not necessarily stronger than the right.

(emphasis mine)

more at: http://www.sfsu.edu/~cadbs/Eng022.html