What is Defective Colour Vision

Defective colour vision is often called colour blindness. The ability to appreciate one or more of the primary colours is lacking. This can be either acquired or congenital. The Greek words for first, second, and third (protos, dueteros, and tritos) are used for the three primary colours. The suffix is added depending on the degree of severity-partial (-anomaly), complete (-anopia), and unspecified (-an). Dyschromatopsia is a condition in which there is colour confusion due to deficiency of colour. Achromatopsia is a condition in which there is a complete lack of colour sensation