VISUAL AGNOSIA definition - the lack of ability to use one's sense of sight to distinguish objects even though eyesight is intact.
Basically they way it was describe to us is that a person that suffers from visual agnosia more than likely has decent eyesight but the area of the brain that processes what the eyes see is malfunctioning.
Here is a visual example of visual agnosia;

This is one visual example that was given to us to understand how our oldest son may be seeing things based on testing.
Click here to see the answer
of what this image is.