A survey of refractive status and stereopsis in school-aged children in the city of Shanghai

Objective To explore the relative contribution of refractive status and stereopsis in a school population and to determine the associations between refractive status and stereoacuity,age,and axial length.Methods Subject data were sampled from the materials of a population-based cluster sampling of children in 8 primary schools in Shanghai in this cross-sectional investigation.According to the standards established for this study,a table was created based on a questionnaire and the examination of vision,stereopsis and axial length of the subjects.SPSS 20 software was used to analyze the data for the different ages (6,7,8,9 and 10 years of age) and refractive status (emmtropia,mild myopia,severe myopia,mild hyperopia and severe hyperopia).A x2 test was used to compare groups.An ANOVA was used to compare the normal distribution measurement data among groups.For non-normal distributions data,nonparametric tests were used throughout.Results ①The trend for the incidence of myopia increased and for the incidence of hyperopia decreased with an increase in age.There was a positive correlation between the prevalence of myopia and increased age (r=0.427,P＜0.01),and a negative correlation between the prevalence of hyperopia and increased age (r=0.269,P＜0.01).There was a significant difference in stereopsis with normal uncorrected vision (Kruskal Wallis,x2=88.867,P＜0.01).There was a statistically significant difference in stereopsis between ages 6 and 7 (Kolmogorov-Smirnov,Z=2.584,P＜0.01),but no difference between ages 7 and 8,8 and 9,and 9 and 10 (P＞0.05).The difference in the detection rate of anomalous stereopsis was statistically significant for different refractive states (x2=57.294,P＜0.01).Stereoacuity also differed significantly among different refractive groups (Kruskal Wallis,x2=67.428,P＜0.01).The differences were statistically significant between severe hyperopia (Z=2.584,P＜0.01),severe myopia (Z=2.138,P＜0.01),and mild hyperopia (Z=1.819,P＜0.01) and normal groups respectively.The mean value of axial length gradually increased with an increase in age and the differences were significant among age groups (F=115.248,P＜0.01).The differences were significant when all age groups were compared to each other (P＜0.01).Conclusion ①The results suggest that the prevalence of myopia increases with age,but the prevalence of hyperopia decreases with age in school-aged children.The eye in school-aged children goes from farsightedness to myopia.②Stereopsis reaches maturity at 7 to 8 years of age.③Mild and severe hypermetropia obviously influenced the development and establishment of stereopsis.④The mean axial length of the eye gradually increased with age.\r\n\r\nKey words: \r\nRefractive error;  Depth perception;  Child (6-12);  Small-area analysis;  Data collection;  Cross-sectional studies