Colour vision testing in pre-school-aged children.

84 children aged from 2 to 6 years were tested with three different pseudo-isochromatic plates: Velhagen Pflügertrident test, Lanthony Tritan Album and Ishihara test. The Velhagen test was correctly interpreted by all of the 6- and 5-year olds, by 80% of the 4-year olds and by 20% of the 3-year olds. The Lanthony Tritan Album was well performed by all of the 6-, 5- and 4-year olds, and by 80% of the 3-year olds. The Ishihara test was acceptably performed by all of the 6- and 5-year olds, by 90% of the 4-year olds and by 40% of the 3-year olds. None of the 2-year olds could understand any of these tests. In the Ishihara test, the winding lines in the plates No. 30 and 32 were difficult for children; the incomplete interpreting of them must be accepted for a correct answer.