Developmental setback in severe visual impairment.

Developmental setback in children initially thought to be of normal cognitive potential is a serious complication of severe visual impairment; the prevalence, diagnostic specificity, clinical presentation, and factors that contribute to its genesis require systematic investigation. The findings are reported of a retrospective case review over a 15 year period of children attending the developmental vision clinic at the Wolfson Centre of the Institute of Child Health. One hundred and two children met the inclusion criteria of a period of normal development confirmed at initial assessment when aged less than 16 months, absence of additional disabilities, and follow up to at least 2.5 years of age. Developmental setback in their second or third year occurred in 10 (31%) of 32 children who were totally blind throughout (minimal perception of light or less), one (4%) of 25 who, though blind at first assessment, showed visual improvement, and none of 49 children with better vision throughout (awareness for near, large objects). This represents a significantly greater risk for totally blind children than for the other groups. The course and characteristics of the affected children varied, but all had visual diagnoses involving the nervous elements of the visual system, and 60% had major social adversity factors. The role of primary maldevelopment of the central nervous system, the degree of visual impairment, the developmental and emotional climate, and the stage of attentional and behavioural development in the causation of adverse developmental outcome are discussed.