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Comparative Study
. 2009 Jun;13(3):253-7.
doi: 10.1016/j.jaapos.2009.01.007. Epub 2009 Apr 5.

A comparison of Lea Symbol vs ETDRS letter distance visual acuity in a population of young children with a high prevalence of astigmatism

Velma Dobson  1 , Candice E Clifford-Donaldson, Joseph M Miller, Katherine A Garvey, Erin M Harvey
Affiliations
Comparative Study

A comparison of Lea Symbol vs ETDRS letter distance visual acuity in a population of young children with a high prevalence of astigmatism

Velma Dobson et al. J AAPOS. 2009 Jun.

Abstract

Purpose: To compare visual acuity results obtained by use of the Lea Symbols chart with results obtained with Early Treatment Diabetic Retinopathy Study (ETDRS) charts in young children who are members of a population with a high prevalence of astigmatism.

Methods: Subjects were 438 children ages 5 through 7 years who were enrolled in kindergarten or first grade on the Tohono O'odham Reservation: 241 (55%) had astigmatism >or=1.00 D in one or both eyes (range, 0.00-6.75 D). While wearing best correction, each child had right eye visual acuity tested with the 62 cm by 65 cm Lea Symbols chart at 3 m and with the 62 cm by 65 cm ETDRS chart at 4 m. Visual acuity was scored as the smallest optotype size at which the child correctly identified 3 of a maximum of 5 optotypes. ETDRS visual acuity also was scored based on the total number of letters that the child correctly identified.

Results: Correlation between Lea Symbols visual acuity and ETDRS visual acuity was 0.78 (p < 0.001). Mean Lea Symbols visual acuity was one-half line (0.04-0.06 logMAR) better than mean ETDRS visual acuity (p < 0.001). The difference between Lea Symbols and ETDRS visual acuity was not correlated with the mean of the Lea Symbols and ETDRS visual acuity scores, which ranged from -0.3 logMAR (20/10) to 0.74 logMAR (20/110).

Conclusions: In this population of young children, in whom the primary source of reduced visual acuity is astigmatism-related amblyopia, the Lea Symbols chart produced visual acuity scores that were about 0.5 line better than visual acuity scores obtained with ETDRS charts.

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Conflict of interest statement

The authors have no financial interest in any of the tests used in this study.

Figures

FIG 1
FIG 1
Lea Symbols versus Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity results for the 438 5- to 7-year-old study participants, with ETDRS visual acuity determined using line-by-line (A) and letter-by-letter (B) scoring. Correlation between Lea Symbols and ETDRS visual acuity was 0.78 (p < 0.001). Dashed line represents perfect agreement between Lea Symbols and ETDRS visual acuity, solid lines represent regression line and 95% confidence interval.
FIG 2
FIG 2
Difference between Lea Symbols and Early Treatment Diabetic Retinopathy Study (ETDRS) visual acuity plotted as a function of the mean of the visual acuity scores obtained with the Lea Symbols and ETDRS charts, with ETDRS visual acuity determined using line-by-line (A) and letter-by-letter (B) scoring. There was no significant correlation between the difference between Lea Symbols and ETDRS visual acuity scores and the mean of the scores. Dashed line represents perfect agreement between Lea Symbols and ETDRS visual acuity, solid lines represent regression line and 95% confidence interval.
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