Changes of refraction in schoolchildren.

The refractions of 1,118 children, aged 7 to 15 years, were followed for one to eight years; 260 children were hyperopic and 828 were myopic throughout the observation time. Thirty additional hyperopic children became myopic during follow-up. In the cross-sectional study, the mean annual change of refraction in hyperopic children varied from -0.03 to -0.11 diopters in different age groups. In myopic children, the variation was from -0.46 to -0.93 D. In the longitudinal follow-up study (from five to eight years), the mean annual change of refraction in hyperopic children was -0.12 D compared with -0.55 D in myopic children. The mean annual change in the 30 hyperopic children who became myopic was -0.21 D while hyperopic and -0.60 D while myopic. The difference is highly significant. It clearly shows that the changes of refraction in hyperopic schoolchildren occur much more slowly than in myopic children of the same age.