AIM: To evaluate the applicability and the development of the normal visual acuity from age 3 to 3.5 years using Lea Symbols and HOTV charts.

METHODS: It was a survey research study. Totally, 133 preschoolers(266 eyes)between 3 to 4.5 years old recruited from two kid-gardens in Guangzhou were tested with both the Lea Symbols chart and the HOTV chart. Outcome measures were monocular logarithm of the minimum angle of resolution(logMAR)visual acuity and inter-eye acuity difference in logMAR units for each test.

RESULTS: The testability rates of the two charts were high(96.24% vs 92.48%, respectively), but difference was not statistically significant(P>0.05). The difference between the two kind of monocular vision was not statistically significant(the right eye: t=0.517, P=0.606; the left eye: t=-0.618, P=0.538). There was no significant difference between different eye(Lea Symbols chart: t=0.638, P=0.525; HOTV chart: t=-0.897, P=0.372). The visual acuities of the boys were better than those of the girls, but the difference was not statistically significant(P>0.05). The results which came from visual acuities with the two charts for the corresponding age groups(3-year-old group, 3.5-year-old group, 4-year-old group, 4.5-year-old group)indicated that the visual acuities of the preschoolers were improving with increasing age, but the difference among the visual acuities with the Lea Symbols chart was not statistically significant(the right eye: F=2.662, P=0.052; the left eye: F=1.850, P=0.143). However the difference among the visual acuities with the HOTV chart was statistically significant(the right eye: F=4.518, P=0.005; the left eye: F=3.893, P=0.011).

CONCLUSION: Both Lea Symbols and HOTV chars are accepted and appropriate for preschool vision screening from 3 to 4.5 years old. The monocular visual acuity of preschoolers from age 3 to 4.5 years could be assessed was similar using the two charts. There is no correlation between visual acuity and different eye. There is no statistical difference between the genders. The results further demonstrate that the preschoolers whose age reached three years old have the ability to accept the Subjective vision checks. Also the development of the normal visual acuity is faster in the early stage.