This study was performed to test the hypothesis that accommodation and convergence differences precede the onset of myopia in children. Records of children who were emmetropic and became myopic (became myopic group) and children who remained emmetropic (remained emmetropic group) were collected from seven private optometry practices. The practices were located in Illinois, Iowa, Oklahoma, and Oregon. Near-point phorias and positive relative accommodation (PRA) findings were significantly different in the two groups by t-test. Negative relative accommodation (NRA) did not show a statistically significant difference in the two groups. Binocular cross-cylinder findings were shown by analysis of variance (ANOVA) to be significantly affected by group (became myopic vs. remained emmetropic) and by practice location. These results support the hypothesis that differences in accommodation and convergence function may be precursors of juvenile onset myopia.
