Colour vision tests for children

The prevalence of colour vision defect is estimated at 8% in males (or one out of every 12) and between 0.4 and 0.5% in females (or 1 out of every 200).^1,2 A classic text, Birch,² explains that the most likely form of colour abnormal vision is inherited, via an X-linked form of inheritance.

A boy may inherit just one X chromosome, so has a 50% chance of expressing the trait whenever the mother is a carrier (the daughter of a male colour defective) or will inherit the trait when it is the rare occasion of the mother being colour defective. So it is typically a boy who gets the disorder and inherits it from his maternal grandfather. Deuteranomalous trichromatism is the most common type of congenital colour vision defect.²