Holmgren's coloured wool test for colour blindness, Europe, 1871-1900
The patient had to match one piece of wool to the samples in the box in this colour blindness test. There are light and dark shades to confuse the patient. This helped detect problems. The numbers on the pieces of wool were codes. The doctor used them to determine what type colour blindness the patient had. Swedish physiologist Alarik Frithiof Holmgren (1831-1897) devised this test in 1874. He pursued his investigations following a railway accident in Sweden in 1876. The accident was believed to be caused by a colour blind train driver. Following Holmgren’s research, colour blindness tests were made compulsory for railway and shipping workers in Sweden.
Related Themes and Topics
Glossary: Diagnosing illness
The branch of medicine dealing with the diseases and surgery of the visual pathways (usually the eyes or the brain).
Glossary: colour blindness test
A test to find whether a person is colour blind. The most commonly used test in the world is the Ishihara test invented in 1917, where numbers are concealed within a circle of different colours.