RESUMEN
PURPOSE: The purpose of this study is to evaluate visual acuity and refractive state in preschool children and to find the environmental factors that cause visual acuity and refractive change. METHODS: The initial subjects were 3, 225 preschool children, aged 4 to 6 years old, selected randomly from 15 preschools in Daejeon from August to November, 1997. Among them, 759 (23.5%) children showed 0.6 or less visual acuity or had different visual acuity of more than 2 lines between two eyes. In addition, 537 (70.8%) children who did not showed organic ocular abnormality during the first examination received refraction. Five years later, 120 (22.3%) children were reexamined and enrolled in this study. RESULTS: Uncorrected visual acuity was 0.44 (log MAR -0.36 +/- 0.27) and corrected visual acuity was 0.85 (logMAR -0.07 +/- 0.09) on average in 1997. Generally there was a myopic shift by -1.30 +/- 1.16 diopter (D) for 5 years (p<0.001) and astigmatism was significantly decreased by 0.32 +/- 0.48 D in the hyperopic group (p<0.001). The amount of myopic shift was lower in the children who were wearing eyeglasses than in those who were not in the hyperopic group (p<0.05). Corrected visual acuity was significantly increased by 0.13 (logMAR 0.06 +/- 0.08, p<0.001). The degree of myopic shift was larger in the children whose parents were wearing eyeglasses than in those whose parents were not wearing eyeglasses (p<0.05) but other environmental factors did not influence on visual acuity or refractive change. CONCLUSIONS: Early examination of visual acuity and refractive state, and adequate treatment are important to increase visual function in preschool children.