19th century colour vision testing stick. Stick of different coloured wools used for testing people for colour blindness. The person being tested was shown a coloured piece of wool and had to pick the same colour from this selection. If colour-blind the person would not be able to pick the correct colour. This test was introduced by Dr William Thomson in 1880. Photographed at the Royal College of Ophthalmologists,London,UK | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / Thomas, Mark |
Taille de l’image : | 5138 px × 3425 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |