Vision impairment varies from person to person and may range from blurred vision, reduced depth and distance perception, sensitivity to glare, tunnel vision to poor night vision. Vision impairment may impact on a person at birth, deteriorate over time or occur suddenly as a result of an accident, hereditary condition, diabetes, glaucoma, stroke, eye infections and congenital conditions.
It is estimated that less than 5% of people with vision impairment are totally blind. Most people have some useful vision. The amount and kind of sight they have, and how well they are able to use it, depend largely on the diagnosis of their particular impairment. An appropriate environment can, however, greatly increase their ability to function independently.