Comparison of visual acuity measurements via three different methods in preschool children: Lea symbols, crowded Lea symbols, Snellen E chart

The aim of this study was to compare three different methods to measure visual acuity (VA) in healthy and amblyopic preschool children: a Snellen E chart (SE), a single Lea symbols (SLS), and a crowded Lea symbols (CLS).

Seventy-eight eyes of 54 patients (28 females, 26 males) were included in this cross-sectional, comparative study. The control group consisted of 30 healthy cases, and the amblyopic group consisted of 24 patients with amblyopia. Best-corrected VA (BCVA) measurements with SLS, CLS, and SE were compared in control eyes (CE), amblyopic eyes (AE), and fellow eyes (FE) separately.

The mean age of the cohort was 5.7 ± 0.7 years (range 5–7 years). The mean refractive error was +1.02 ± 0.36 D (diopter, spherical equivalent) in CE, +5.59 ± 2.45 D in AE, and +3.96 ± 2.38 D in FE. The median BCVA (logMAR) was (in order of SLS, CLS, and SE) 0.00 [interquartile range (IQR) 0.10], 0.10 (IQR 0.10), 0.00 (IQR 0.10) in CE, 0.25 (IQR 0.33), 0.35 (IQR 0.30), 0.25 (IQR 0.38) in AE, and 0.10 (IQR 0.08), 0.10 (IQR 0.00), 0.10 (IQR 0.10) in FE. There was no statistically significant difference between the three methods in terms of the CE or FE (p > 0.05). In contrast, there was a statistically significant difference in AE (p < 0.05). The mean VA measurement with SLS was higher compared with CLS in AE. A positive and strong correlation between the three charts was found in all of the groups (p < 0.001).

We found SLS, CLS, and SE to be consistent: all three methods can be used to obtain measurements of VA in healthy and amblyopic preschool children.