Causes of visual impairment in children.

The populations formed by the pupils of the eleven Dutch institutions for visually handicapped children on the first of January 1980 were investigated, repeating the investigation of the International Association for Prevention of Blindness in 1970. The total number of pupils was nearly the same in both instances (1300 in 1970 and 1334 in 1980). No significant differences were found in the distribution of diagnoses and etiologies between the two groups. The congenital cataracts, the tapeto-retinal dystrophies and the optic nerve affections are still the three diagnostic groups with the highest prevalence (together 48.6%). To gain more reliable insight into morbidity patterns one needs longitudinal investigations with central registration of patient data, especially in studying the influence of pre- and perinatal problems.