Investigation of the Visual Acuity Test Success Rate of a New Child-Friendly Minimum-Separable Chart for 2- and 3-Year-Old Children

<b>Background/Objectives:</b> Early detection and timely treatment of amblyopia require reliable visual acuity testing in toddlers; however, conventional Landolt ring charts often show poor testability in 2-3-year-old children. Therefore, we aimed to verify the practicality of a new Child-Friendly Minimum-Separable (CFMS) chart for 2-3-year-old children by comparing cooperation rates with the standard Landolt ring visual acuity chart. <b>Methods:</b> A prospective pilot study was conducted on 20 children aged 2 years (30.6 ± 3.2 months) and 20 children aged 3 years (41.8 ± 3.9 months). Right-eye visual acuity was tested in random order using the Landolt ring (four options, 3/5 considered correct) and the CFMS chart (two options, 3/3 considered correct). Test cooperation rates and visual acuity were analyzed. <b>Results:</b> In the 2-year-olds, the cooperation rate was 15% and 75% for the Landolt ring and CFMS chart, respectively (<i>p</i> = 0.0005). Twelve children refused to cooperate with the Landolt ring but cooperated with the CFMS chart; the reverse did not occur. In the 3-year-olds, the cooperation rate was 60% and 90% for the Landolt ring and CFMS chart, respectively (<i>p</i> = 0.031); six children cooperated only with the CFMS chart. The odds ratio for cooperation per additional month of age was 1.34 (95% confidence interval [CI]: 1.12-1.59; <i>p</i> = 0.001) and 1.24 (95% CI: 1.03-1.50; <i>p</i> = 0.026) for the Landolt ring and CFMS chart, respectively. <b>Conclusions:</b> Compared to the Landolt ring, the CFMS chart significantly improves cooperation rates for visual acuity testing in 2-3-year-old children, especially among 2-year-olds.