Holmgren's wool test

Holmgren's colored wool test is a color vision test method introduced in 1874 by the Swedish physiologist Alarik Frithiof Holmgren (1831-1897). Holmgren studied the electrical response of the retina to light. Holmgren's test gained attention following Lagerlunda rail accident in Sweden in 1875. Suspecting that the train's engineer (who had died in the accident) was color blind, Holmgren decided to examine the 266 employees of the Uppsala Gabole line, and as he suspected, thirteen of them were found to be color blind. The original Holmgren test was the first successful attempt to standardize the detection of color blindness. British Board of Trade used Holmgren's wool test to test the color vision of seafarers from 1895 to 1913. ==Test==

In Holmgren's wool test, the patient is asked to match coloured skeins of yarn to the samples in the box. At first, the patient is asked to select from the 40 skeins, 10 skeins that best match the light green master A. If the patient choose gray or dark brown colors on the green color matching, it indicates that they may have a green blindness problem. If the subject prefers green or yellow colors in the violet color test, they are defective to violet. ==References==