Guimaraes S, et al. - An investigation was pursued of a normative of tumbling E optotype and its feasibility for visual acuity (VA) analysis, in children aged 3-4 years. This research served as the first normative for European Caucasian children with single crowded tumbling E in healthy eyes. It compared the 3 and 4 years old testability. Higher testability rates were discovered when compared to other optotypes, especially in children aged 3 years. It displayed 5%-11% better testability rates.