COLOUR-BLINDNESS

Otago Daily Times, Issue 25829, 27 April 1945, Page 8

COLOUR-BLINDNESS

Colour-blindness is not often acquired. It is only in rare cases (states tne department of Health) that injury or disease of the eye brings on colourblindness. Most colour-blindness is congenital. The condition is hereditary, running in families, usually from a colour-blind grandfather, through a normal mother, to a colour-blind grandson. Females are rarely affected, though they are the ones who transmit it. The condition is much' more common than people realise. Between two and four males in every 100 will be grossly colour-blind, and a very much larger percentage will be slightly affected. It is so rare in females that girls are usually not tested for the condition. The commonest form of colour-blind-ness is the confusion of red and green. Various tests need to be applied before an individual can be classified as definitely colour-blind. One much used in the past was the Holmgren test, which consisted in matching coloured wools. One much used now is the Ishahara test made by reading letters formed by coloured dots on a background of other dots. Where there is any doubt further tests are available. but they are the job of an eyespecialist. As soon as a boy shows interest in his future and says definitely what he would like to be, his parents should think whether the calling the boy is going to study or train for is one that calls for the absence of colour-blind-ness. For colour-blindness is not tested for in schools in routine medical examinations. The confusion of reds and greens would be dangerous in certain occupations—for example, railway signalmen, engine drivers, sailors. The air force pilot or naval man must obviously not be colour-blind. As nothing can be done to change the condit'on to normal, much disappointment will be avoided if colour-blind boys are discouraged from training for any occupation where the use of colours is involved.