1119 hypermetropic children have been followed from the age of 6 months to 3 1/2 years. Observations are reported on (i) the changes in their refraction and (ii) their accommodation. Children who eventually had either a convergent squint or a microtropia were significantly (i) less likely to have spontaneously reduced their hypermetropia, and (ii) more likely to have problems with their accommodation, than those who had no squint. These abnormalities were demonstrated in both the fixing and the non-fixing eyes. There was no obvious difference between the findings for children who had microtropia and squint. We suggest that there was a basic defect in the function, and/or the development, of the visual systems relating to both fixing and non-fixing eyes of children who had squint or microtropia; and that this defect was present before squint or microtropia were diagnosed. The question of whether this defect had a congenital or an acquired (form vision deprivation) cause is discussed.