This review draws together current understanding of the impact of visual impairment (VI) on early neurodevelopmental and neurobiological processes. The impact is recognized as being substantial. Two major problems make it difficult to draw conclusions from much of the literature on this subject. The first is the heterogeneity of samples of children with VI in terms of additional impairments that introduce multiple confounding variables: in Western societies the prevalence of additional impairments is 60 to 70%. Secondly, subgrouping according to the degree or severity of VI is inconsistent and can be suboptimal for developmental studies of infancy. Our group has reconsidered these questions of taxonomy and applied new ones to our recent research cohorts.