Blindness refers to a complete absence of or a very low level of vision. Onset in adulthood has significant implications for employment, leisure, and psychological well-being. Congenital blindness, however, creates profound developmental challenges from infancy onward, leading to an increased risk of intellectual and developmental disability, which may be mild or severe. Early specialized support for the child and family is required to optimize outcomes.

In this entry, some definitions of blindness are given, with comments on their limitations as applied to children. The impact of blindness on early developmental processes is also described. Finally, this entry examines the causes of congenital blindness.