Sometimes it is possible for a person with CVI to see things while moving their gaze around that they didnt detect when stationary. However, movement that is too fast can be hard to track; some people find that fast-moving objects "disappear." Materials with reflective properties, which can simulate movement, may be easier for a person with CVI to see. However, too many reflections can be confusing (see cognitive overload). Some objects may be easier to see than others. For example, the person may have difficulty recognising faces or facial expressions but have fewer problems with written materials. This is presumably due to the different way that the brain processes different things. Colour and contrast are important. The brains colour processing is distributed in such a way that it is more difficult to damage, so people with CVI usually retain full perception of colour. This can be used to advantage by colour-coding objects that might be hard to identify otherwise. Sometimes yellow and red objects are easier to see, as long as this does not result in poor contrast between the object and the background. People with CVI strongly prefer a simplified view. When dealing with text, for example, the person might prefer to see only a small amount of it at once. People with CVI frequently hold text close to their eyes, both to make the text appear larger and to minimise the amount they must look at.
Cortical visual impairment (CVI) is a form of visual impairment that is caused by a brain problem rather than an eye problem. (The latter is sometimes termed "ocular visual impairment" when discussed in contrast to cortical visual impairment.) Some people have both CVI and a form of ocular visual impairment. CVI is also sometimes known as cortical blindness, although most people with CVI are not totally blind. The term neurological visual impairment (NVI) covers both CVI and total cortical blindness. Delayed visual maturation, another form of NVI, is similar to CVI, except the childs visual difficulties resolve in a few months. Though the vision of a person with CVI may change, it rarely if ever becomes totally normal. The major causes of CVI are as follows: asphyxia, hypoxia (a lack of sufficient oxygen in the bodys blood cells), or ischemia (not enough blood supply to the brain), all of which may occur during the birth process; developmental brain defects; head injury; hydrocephalus (when the cerebrospinal fluid does not circulate properly around the brain, and collects in the head, putting pressure on the brain); a stroke involving the occipital lobe; and infections of the central nervous system, such as meningitis and encephalitis. Visual and Behavioural Characteristics
Visual and Behavioural Characteristics of CVI are individual and may include several (but not necessarily all) of the following:

The person with CVI may exhibit what at first appears to be frequent variable changes in vision.