Osterberg Children's Eye Test Chart
Lithographic print on card
Nyrop & Maag AS, Copenhagen
25 x 15 ins / 63 x 39 cms
The Osterberg Pictorial Sight-Test Chart for Little Children
Fourth revised edition
In this sight-test chart a series of pictures take the place of the types (or rings) commonly used. The picture subjects chosen are all within the scope of little childrens ideas, and the execution of the pictures has been based to a great extent on drawings actually performed by Children .. Before the final execution of he chart the pictures have been tested in Copenhagen childrens hospitals, and only such figures that have been recognised and interpreted correctly in at least 80 per cent of the cases by children between two and five years of age with normal eyes, at the distance indicated (in metres) to the right of the line. from this distance the details of the figures are seen at a visual angle of 1 minute . So, if a child is placed at a distance of 6 metres from the well lighted sight-test chart and is able at this distance to read the pictures ub=n the line marked with a 6, the childs visual acuity is 6/6, or normal, If only the line which is marked with a 9 can be read from the same distance, the visual acuity is 6/9, and so on.