Comparison Of Visual Acuity Measurements With Standard Logarithmic Visual Acuity Chart,Lea Symbols Chart,ETDRS Chart In Preschool Children

Purpose: The main purpose of this study was to measure testability and repeatability of Standard Logarithmic Visual Acuity Chart,Lea Symbols Chart,ETDRS Chart in preschool children,and to compare visual acuities measuring among three charts.Methods: Uncorrected monocular visual acuity was measured with Lea Symbols Chart,ETDRS Chart and Standard Logarithmic Visual Acuity Chart in random order on 241 preschool children from 42 to 78 months(mean,61.9+10.29months)from a kindergarten in Quangang District of Quanzhou,China.A comprehensive ophthalmological examination was performed by trained ophthalmologists and optometrists,including slit lamp examination,anterior segment examination,fundus examination,ocular motility,ocular alignment,cover test,noncycloplegic refraction.Each child completed three charts measurement and monocular distance visual acuity scores were presented in IogMAR(logarithm of the minimum angle of resolution).Visual acuity was tested twice in each eye of 241 children.Statistical methods were used in data analysis included the normality test,descriptive statistics,rank correlation analysis,chi square tests,rank sum test,Intra class correlation(ICC),weighted Kappa test,Bland-Altman analysis,et al.Descriptive statistics was used to determine the variance among the charts.Results: 1.For all children,the average testability rate between test and retest of Lea Symbols Chart,ETDRS Chart and Standard Logarithmic Visual Acuity Chart were 96.9%,95.45% and 95.2%.The difference was not statistically significant(chi square tests,Pearson χ2test=3.216,P=0.200>0.05;Pearson χ2retest=1.677,P=0.432>0.05).Testability significantly increased with age for all visual acuity tests(p<0.001).2.For all children,agreement measured with kappa statistics between test andretest of Lea Symbols Chart,ETDRS Chart and Standard Logarithmic Visual Acuity Chart were 0.6220,0.6922 and 0.6225.Intra class correlation(ICC)between test and retest of three charts were 0.801,0.832 and 0.809.All the three visual acuity charts had good consistency in test and retest measurements.Children without refractive errors(Spherical equivalent,SE:-0.25~+1.75DS;Astigmatism<0.50DC),between gender groups in test-retest reliability assessed had no statistical differences(Mann-Whitney tests,PLea=0.292,PETDRS=0.139,PSLVAC=0.910>0.05).3.For all children,the correlation of visual acuity obtained with three charts was statistically significant(Spearman Correlation coefficient=0.646、0.630、0.725,p<0.001).But there were significant differences between measured visual acuities with three charts(Friedman tests,P<0.001).The average visual acuity measured with Lea Symbols chart was better than ETDRS chart.And the highest average visual acuity attained using the Standard Logarithmic Visual Acuity Chart.4.In children without refractive errors,There was a significant correlation between visual acuities and ages(Spearman Correlation analysis,P<0.001).Visual acuities increased gradually as the age increasing.5.Interocular visual acuity differences showed good correlation for the three charts in 241 preschool children(Spearman Correlation analysis,P<0.01).There were no statistical differences(Friedman test,Ptest=0.377,Pretest=0.776,>0.05).Conclusion:Preschool stage is the important period of visual cognition development.Visual acuities and testability increased gradually as the age increasing.Therefore,it is significant to evaluate visual acuity of preschool children Accurately and reliably.This study demonstrated that preschool children had high visual acuity testability by using Lea Symbols Chart,ETDRS Chart and Standard Logarithmic Visual Acuity Chart.Besides,test-retest reliability was high for these three visual acuity charts,the repeatability of measured visual acuities with ETDRS Chart is higher than the other two charts and the highest VA attained using the Standard Logarithmic Visual Acuity Chart.Although there were significant differences in measured visual acuities with three charts for their differences of optotypes and design parameters,all three visual acuity charts are recommended for clinic examination of preschool children.